U.S. patent application number 09/912616 was filed with the patent office on 2002-01-03 for alloys formed from cast materials utilizing equal channel angular extrusion.
Invention is credited to Ferrasse, Stephane, Segal, Vladimir, Willett, William B..
Application Number | 20020000272 09/912616 |
Document ID | / |
Family ID | 23848035 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020000272 |
Kind Code |
A1 |
Segal, Vladimir ; et
al. |
January 3, 2002 |
Alloys formed from cast materials utilizing equal channel angular
extrusion
Abstract
Described is a high quality sputtering target and method of
manufacture which involves application of equal channel angular
extrusion.
Inventors: |
Segal, Vladimir; (Veradale,
WA) ; Willett, William B.; (Spokane, WA) ;
Ferrasse, Stephane; (Veradale, WA) |
Correspondence
Address: |
GREGORY M. HOWISON
ROSS, HOWISON, CLAPP & KORN
740 E. CAMPBELL ROAD, SUITE 900
RICHARDSON
TX
75081
|
Family ID: |
23848035 |
Appl. No.: |
09/912616 |
Filed: |
July 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09912616 |
Jul 24, 2001 |
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09465492 |
Dec 16, 1999 |
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Current U.S.
Class: |
148/518 ;
204/192.2 |
Current CPC
Class: |
C23C 14/3414 20130101;
B21C 23/001 20130101 |
Class at
Publication: |
148/518 ;
204/192.2 |
International
Class: |
C23C 014/00 |
Claims
We claim:
1. A sputtering target made by a process including casting having a
target surface with the following characteristics: a) substantially
homogenous composition at any location; b) substantial absence of
pores, voids, inclusions and other casting defects; c) substantial
absence of precipitates; d) grain size less than about 1 .mu.m; and
e) substantially uniform structure and texture at any location.
2. A sputtering target according to claim 1 comprising Al, Ti, Cu,
Ta, Ni, Mo, Au, Ag, Pt.
3. A sputtering target according to claim 1 comprising Al and about
0.5 wt. % Cu.
4. A method for fabricating an article suitable for use as a
sputtering target comprising the steps of: a. providing a cast
ingot; b. homogenizing said ingot at time and temperature
sufficient for redistribution of macrosegregations and
microsegregations; and c. subjecting said ingot to equal channel
angular extrusion to refine grains therein.
5. A method according to claim 4 further comprising, after
subjecting said ingot to equal channel angular extrusion to refine
grains therein, manufacturing same to produce a sputtering
target.
6. A method according to claim 4 wherein said ingot is subject to 4
to 6 passes of equal channel angular extrusion.
7. A method of making a sputtering target comprising the steps of:
a. providing a cast ingot with a length-to-diameter ratio up to 2;
b. hot forging said ingot with reductions and to a thickness
sufficient for healing and full elimination of case defects; c.
subjecting said hot forged product to equal channel extrusion; and
d. manufacturing into a sputtering target.
8. A method of fabricating an article suitable for use as a
sputtering target comprising the steps of: a. providing a cast
ingot; b. solutionizing heat treating said cast ingot at
temperature and time necessary to dissolve all precipitates and
particle bearing phases; and c. Equal channel angular extruding at
temperature below aging temperatures.
9. A method according to claim 8 further comprising manufacturing
to produce a sputtering target.
10. A method according to claim 4 including: a. homogenizing the
ingot; b. hot forging of the ingot; and c. Equal channel angular
extruding forged billet.
11. A method according to claim 7 including: a. hot forging the
ingot; and b. equal channel angular extruding the forget
billet.
12. A method according to claim 10 further comprising producing a
sputtering target.
13. A method according to claim 11 further comprising producing a
sputtering target.
14. A method according to claim 1 further comprising a
solutionizing heat treatment prior to equal channel angular
extrusion.
15. A method according to claim 1 further comprising water
quenching after homogenizing.
16. A method according to claim 7 including: a. heating the cast
ingot before forging at a temperature and for a time sufficient for
solutionizing; b. hot forging at a temperature above solutionizing
temperature; and c. water quenching the forged billet immediately
after forging.
17. A method according to claim 4 including: a. cooling the ingot
after homogenizing to a forging temperature above the solutionizing
temperature; b. Hot forging at a temperature above the
solutionizing temperature; and c. water quenching the forged billet
immediately after forging step.
18. A method according to claims 4, 7 or 8 including aging after
solutionizing and water quenching at a temperature and for a time
sufficient to produce fine precipitates with an average diameter of
less than 0.5 .mu.m.
19. A billet for equal channel angular extrusion of targets
fabricated from a cast ingot of diameter do and length ho which has
been forged into a disc of diameter d.sub.o and thickness h.sub.o
and from which two segments from two opposite sides of forged
billet to provide a billet width A have been removed in such a
manner that thickness H corresponds to the thickness of the billet
for equal channel angular extrusion, the wide A corresponds to the
dimension of square billet for equal channel angular extrusion, and
dimensions of the cast ingot and the forged billet are related by
the formulae:D=1.18Ad.sub.o.sup.2h.sub.o=1.39.A.sup.2H
20. A method according to claims 4, 7 or 8 in which the step of
equal channel angular extrusion is performed at a temperature below
the temperature of static recrystallization and at a speed
sufficient to provide uniform plastic flow, and for a number of
passes and routes that provides dynamic recrystallization during
processing.
21. A method according to claims 5, 9 or 13 including annealing
after final target fabrication at the temperature which is equal to
the temperature of the sputtered target surface during steady
sputtering.
22. A method according to claim 13 in which annealing after final
target fabrication is performed gradientally by exposing the
sputtered target surface to the same heating condition and exposing
an opposite target surface to the same cooling condition as under
target sputtering during a sufficient time for steady
annealing.
23. A method according to claim 22 in which gradient annealing of
the target is performed directly in a sputtering machine at
sputtering conditions before starting a production run.
24. A method according to claims 4, 7 or 8 in which the step of
equal channel angular extrusion include a first extrusion with 1 to
5 passes into different directions intermediate annealing at a low
temperature and for a time sufficient to produce very fine
precipitates of average diameter less than about 0.1 .mu.m, and a
second extrusion with a sufficient number of passes to develop a
dynamically recrystallized structure.
25. A method for controlling texture of sputtering targets by a
process according to claim 4 wherein the step of equal channel
angular extrusion is performed by changing the number of passes and
billet orientation between successive passes in a manner-to produce
a desired final texture strength and orientation.
26. A method for controlling texture of sputtering targets by a
process according to claim 5 wherein the step of equal channel
angular extrusion is performed by changing the number of passes and
billet orientation between successive passes in a manner to produce
a desired final texture strength and orientation.
27. A method for controlling texture of sputtering targets by a
process according to claim 8 wherein the step of equal channel
angular extrusion is performed by changing the number of passes and
billet orientation between successive passes in a manner to produce
a desired final texture strength and orientation.
28. A method according to claim 25 including a preliminary
processing performed before extrusion to produce strong original
texture of the same orientation as of the desired final texture
after equal channel angular extrusion.
29. A method according to claim 25 including the additional step of
recovery annealing performed between extrusion passes at
temperatures below the temperature of static recrystallization.
30. A method according to claim 25 including the additional step of
recovery annealing after equal channel angular extrusion at
temperatures below the temperature of static recrystallization.
31. A method-according to claim 25 including the additional step of
recrystallization annealing performed between extrusion passes at a
temperature equal to the beginning temperature of static
recrystallization.
32. A method according to claim 25 including the additional step of
annealing performed after the step of equal channel angular
extrusion at a temperature equal to the beginning temperature of
static recrystallization.
33. A method according to claim 25 including the additional step of
recrystallization annealing performed between extrusion passes at
temperature above the temperature of full static
recrystallization.
34. A method according to claim 25 including the additional step of
recrystallization annealing performed after the step of equal
channel angular extrusion at temperatures above the temperature of
full static recrystallization.
35. A method according to claims 4, 7 or 8 wherein at least
different types of thermal treatments are performed between
extrusion passes and after the final step of equal channel angular
extrusion.
36. A method according to claim 4, 7 or 8 further comprising a
thermal treatment for control of grain size and distribution of
second phase particles.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to application Ser. No.
09/098,761, filed Jun. 17, 1998.
BACKGROUND OF THE INVENTION
[0002] The invention relates to sputtering targets and methods of
making same; and to sputtering targets of high purity metals and
alloys. Among these metals are Al, Ti, Cu, Ta, Ni, Mo, Au, Ag, Pt
and alloys thereof, including alloys with these and or other
elements. Sputtering targets may be used in electronics and
semiconductor industries for deposition of thin films. To provide
high resolution of thin films, uniform and step coverages,
effective sputtering rate and other requirements, targets should
have homogenous composition, fine and uniform structure,
controllable texture and be free from precipitates, particles and
other inclusions. Also, they should have high strength and simple
recycling. Therefore, significant improvements are desired in the
metallurgy of targets especially of large size targets.
[0003] A special deformation technique known as equal channel
angular extrusion- (ECAE) described in U.S. Pat. Nos. 5,400,633;
5,513,512; 5,600,989; and 5,590,389 is used with advantage in
accordance with the invention. The disclosures of the
aforementioned patents are expressly incorporated herein by
reference.
SUMMARY OF THE INVENTION
[0004] The invention relates to a sputtering target made by a
process including casting. The target has a target surface such
that the surface of the target subjected to sputtering (referred to
as target surface) has a substantially homogeneous composition at
any location, substantial absence of pores, voids, inclusions and
other casting defects, grain size less than about 1 .mu.m and
substantially uniform structure and texture at any location.
Preferably, the target comprises at least one of Al, Ti, Cu, Ta,
Ni, Mo, Au, Ag, Pt and alloys thereof.
[0005] The invention also relates to a method of manufacturing a
target, as described above. The method comprises fabricating an
article suitable for use as a sputtering target comprising the
steps of:
[0006] a. providing a cast ingot;
[0007] b. homogenizing said ingot at time and temperature
sufficient for redistribution of macrosegregations and
microsegregations; and
[0008] c. subjecting said ingot to equal channel angular extrusion
to refine grains therein.
[0009] More particularly, a method of making a sputtering target
comprising the steps of:
[0010] a. providing a cast ingot with a length-to-diameter ratio up
to 2;
[0011] b. hot forging said ingot with reductions and to a thickness
sufficient for healing and full elimination of case defects;
[0012] c. subjecting said hot forged product to equal channel
extrusion; and
[0013] d. manufacturing into a sputtering target.
[0014] Still more particularly, a method of fabricating an article
suitable for use as a sputtering target comprising the steps
of:
[0015] a. providing a cast ingot;
[0016] b. solutionizing heat treating said cast ingot at
temperature and time necessary to dissolve all precipitates and
particle bearing phases; and
[0017] c. Equal channel angular extruding at temperature below
aging temperatures.
[0018] After fabricating as described to produce an article, it may
be manufactured into a sputtering target.
DESCRIPTION OF THE DRAWINGS
[0019] FIGS. 1A-1D are schematic diagrams showing processing steps
of billet preparation for ECAE;
[0020] FIG. 2 is a graph showing the effect of annealing
temperature on billet strength after 4 and 6 passes of ECAE for Al
0.5 wt. % Cu alloy;
[0021] FIG. 3A is a schematic diagram disclosing an apparatus for
gradient annealing of targets;
[0022] FIG. 3B is a schematic diagram showing temperature
distribution through target cross-section C-C during gradient
annealing;
[0023] FIG. 4 is an illustration of (200) pole figures for Al 0.5
wt. % Cu alloys processed with 2, 4 and 8 passes of route D, (in
FIG. 5) respectively;
[0024] FIG. 5 is a graph showing the effect of number of passes and
route on texture intensity after ECAE of Al with 0.5 wt. % Cu;
[0025] FIG. 6 is a graph showing the effects of annealing
temperature for route A after ECAE of Al with 0.5 wt. % Cu;
[0026] FIG. 7 is a graph showing the effects of annealing
temperature on texture intensity for route B after ECAE of Al with
0.5 wt. % Cu;
[0027] FIG. 8 is a graph showing the effects of annealing
temperature on texture intensity for route C after ECAE of Al with
0.5 wt. % Cu;
[0028] FIG. 9 is a graph showing the effects of annealing
temperature on texture intensity for route D after ECAE of Al with
0.5 wt. % Cu:
[0029] FIG. 10 is a pole figure illustrating the texture as a
result of the process described; and
[0030] FIGS. 11, 11A and 11B are schematic diagrams of an apparatus
for ECAE of billets for targets.
DETAILED DESCRIPTION
[0031] The invention contemplates a sputtering target having the
following characteristics:
[0032] substantially homogenous material composition at any
location;
[0033] substantial absence of pores, voids, inclusions and other
casting defects;
[0034] substantial absence of precipitates;
[0035] grain size less than about 1 .mu.m;
[0036] fine stable structure for sputtering applications;
[0037] substantially uniform structure and texture at any
location;
[0038] high strength targets without a backing plate;
[0039] controllable textures from strong to middle, weak and close
to random;
[0040] controllable combination of grain size and texture;
[0041] large monolithic target size;
[0042] prolonged sputtering target life;
[0043] optimal gradient of structures through target thickness.
[0044] Targets possessing these characteristics are producible by
the processes described.
[0045] Because of high purity, cast ingot metallurgy is useful in
most cases for billet fabrication in target production. However,
casting results in a very course dendritic structure with strong
non-uniformity in the distribution of constitutive elements and
additions across the ingot and large crystallites. Moreover, high
temperature and long-time homogenizing cannot be applied in current
processing methods because of the further increase of grains. One
embodiment of the invention solves this problem by using
homogenizing time and temperature sufficient for redistribution of
macrosegregations and microsegregations followed by equal channel
angular extrusion (ECAE) with a sufficient number of passes,
preferably from 4 to 6, for grain refinement.
[0046] Another embodiment eliminates other casting defects such as
voids, porosity, cavities and inclusions which cannot be optimally
removed by homogenizing and employs a hot forging operation. In
currently known methods hot forging has a restricted application
because reductions are limited and are typically used at low
temperature working for grain refinement. Other processes do not
solve that problem when slab ingots of the same thickness as the
billet for ECAE are used. In the present invention, the as-cast
ingot has a large length-to-diameter ratio, preferably up to 2.
During hot forging, the ingot thickness changes to the thickness of
the billet for ECAE. That provides large reductions which are
sufficient for full healing and elimination of cast defects.
[0047] Still another embodiment of the invention is directed to
precipitate- and particle-free targets. With currently known
methods precipitate-free material may be prepared by solutionizing
at the last processing step. However, in this case heating to
solutionizing temperatures produces very large grains. The present
invention provides a method for fabricating precipitate-free and
ultra-fine grained targets. According to this embodiment of-the
invention, solutionizing is performed at a temperature and time
necessary to dissolve all precipitates and particle bearing phases
and is followed by quenching immediately before ECAE. Subsequent
ECAE and annealing are performed at temperatures below aging
temperatures for corresponding material conditions.
[0048] A further embodiment of the invention is a special sequence
of homogenizing, forging and solutionizing operations. As-cast
ingots are heated and soaked at the temperature and for the length
of time necessary for homogenizing, then cooled to the starting
forging temperature, then forged to the final thickness at the
final forging temperature (which is above the solutionizing
temperature) and quenched from this temperature. By this embodiment
all processing steps are performed with one heating. This
embodiment also includes another combination of processing steps
without homogenizing: forging at a temperature of about the
solutionizing temperature and quenching immediately after
forging.
[0049] It is also possible in accordance with the invention to
conduct aging after solutionizing at the temperature and for the
length of time necessary to produce fine precipitates with an
average diameter of less than 0.5 .mu.m. These precipitates will
promote the development of fine and uniform grains during following
steps of ECAE An additional embodiment of the invention is a billet
for ECAE after forging. An as-cast cylindrical ingot of diameter do
and length ho (FIG. 1A) is forged into a disk of diameter D and
thickness H (FIG. 1B). The thickness H corresponds to the thickness
of the billet for ECAE. Then two segments are removed from two
opposite sides of the forged billet such as by machining or sawing
(FIG. 1C), to provide a dimension A corresponding to a square
billet for ECAE (FIG. 1D). ECAE is performed in direction "C" shown
on FIG. 1C. After the first pass the billet has a near-square
-shape if the dimensions of the ECAE billet (AxAxH), the dimensions
of the forged disk (DxH) and the dimensions of the cast ingot
(d.sub.oxh.sub.o)are related by the following formulae:
D=1.18A
d.sub.o.sup.2h.sub.o=1.39.A.sup.2H
[0050] The invention further contemplates the fabrication of
targets with fine and uniform grain structure. ECAE is performed at
a temperature below the temperature of static recrystallization
with the number of passes and processing route adjusted to provide
dynamic recrystallization during ECAE. Processing temperature and
speed are, correspondingly, sufficiently high and sufficiently low
to provide macro- and micro-uniform plastic flow.
[0051] A method for fabricating fine and stable grain structures
for sputtering applications and to provide high strength targets is
also provided. The billet after ECAE with dynamically
recrystallized sub-micron structure is additionally annealed at the
temperature which is equal to the temperature of the target surface
during steady sputtering. Therefore, the temperature of the target
cannot exceed this sputtering temperature and for structure to
remain stable during target life. That structure is the finest
presently possible stable structure and provides the best target
performance. It also provides a high strength target. FIG. 2 shows
the effect of the annealing temperature on the ultimate tensile
strength and yield stress of Al 0.5 wt. % Cu alloy after ECAE at
room temperature with 6 or 4 passes. In both cases as-processed
material has high strength not attainable for that material with
known methods. Yield stress is only slightly lower than ultimate
tensile strength. The increase of the annealing temperature in a
range from 125.degree. C. to 175.degree. C. that, it is believed,
corresponds to possible variations of sputtering temperature
results in the gradual decrease of strength. However, even in the
worst case with an annealing temperature of 175.degree. C. target
strength and, especially, yield stress are much higher than the
strength of aluminum alloy AA6061 at T-O condition which is the
most widely used for fabrication of backing plates (see FIG. 2).
Thus, among other things, the invention provides the following
significant advantages:
[0052] High strength monolithic targets may be fabricated from mild
materials like pure aluminum, copper, gold, platinum, nickel,
titanium and their alloys.
[0053] It is not necessary to use backing plates with additional
and complicated operations such as diffusion bonding or
soldering.
[0054] Fabrication of large targets is not a problem.
[0055] Targets may easily be recycled after their sputtering life
ends.
[0056] It is also useful to employ gradient annealing of targets
after ECAE. For that purpose a preliminary machined target is
exposed to the same thermal conditions as under sputtering
conditions and kept at those conditions a sufficient time for
annealing. FIG. 3 describes that processing. The target 1 is fixed
in a device 2 which simulates sputtering: a bottom surface A of the
target is cooled by water while a top surface B is heated to the
sputtering temperature. Heating is advantageously developed at the
thin surface layer by radiant energy q (left side of FIG. 3A) or
inductor 3 (right side of FIG. 3A) In addition it is also possible
to achieve gradient annealing of targets directly in a sputtering
machine at the regular sputtering conditions before starting the
production run. In all these cases distribution of temperature
through the target as shown in FIG. 3B through sections C-C of FIG.
1 is non-uniform and annealing takes place only inside a very thin
surface layer (.delta.). Following sputtering the same distribution
is maintained automatically. Thus, structural stability and high
strength of as-processed material are conserved for the main part
of the target.
[0057] An additional embodiment comprises a two-step ECAE
processing. At the first step ECAE is performed with a low number
of passes, preferably from 1 to 3, in different directions. Then,
the preliminary processed billet receives aging annealing at low
enough temperatures but for sufficient time to produce very fine
precipitates of average diameter less than about 0.1 .mu.m. After
intermediate annealing ECAE is repeated with the number of passes
necessary to develop a dynamically recrystallized structure with
the desired fine and equiaxed grains.
[0058] It is also possible through use of the invention to control
texture. Depending on the starting texture and the nature of the
materials, various textures can be created. Four major parameters
are important to obtain controlled textures:
[0059] Parameter 1: the number of repeated ECAE passes subjected to
the same work piece. This number determines the amount of plastic
deformation introduced at each pass. Varying the tool angle between
the two channels of the ECAE equipment enables the amount of
plastic straining to be controlled and determined and therefore
represents an additional opportunity for producing specific
textures. Practically, in most cases, a tool angle of about
90.degree. is used since an optimal deformation (true shear strain
.epsilon.=1.17) can be attained;
[0060] Parameter 2: the ECAE deformation route; that is defined by
the way the work piece is introduced through the die at each pass.
Depending on the ECAE route only a selected small number of shear
planes and directions are acting at each pass during plastic
straining.
[0061] Parameter 3: annealing treatment that comprises heating the
work piece under different conditions of time and temperature. Both
post-deformation annealing at the end of the ECAE extrusion and
intermediate annealing between selected ECAE passes are effective
ways to create various textures. Annealing causes the activation of
different metallurgical and physical mechanisms such as
second-phase particle growth and coalescence, recovery and static
recrystallization, which all affect more or less markedly the
microstructure and texture of materials. Annealing can also create
precipitates or at least change the number and size of those
already present in the material: this is an additional way to
control textures.
[0062] Parameter 4: the original texture of the considered
material.
[0063] Parameter 5: the number, size and overall distribution of
second-phase particles present inside the material.
[0064] With consideration of these five major parameters, control
of texture is possible in the ways described below:
[0065] Table 1 describes major components of texture between 1 and
8 ECAE passes via routes A through D in the as deformed condition
for a strong initial texture and also for routes A and D for a weak
initial texture. To describe major components both the 3 Euler
angles (.alpha..beta..gamma.) according to the Roe/Matthies
convention and ideal representation {xyz} <uvw> are used.
Moreover, the total volume percentage of the component is given.
For texture strength both the OD index and Maximum of pole figures
are given.
1TABLE 1 Number Major Texture Orientations Notation: OD Maximum of
of Euler angles (.alpha..beta..gamma.):{xy- z}<uvw>:% total
index Pole Figures passes N volume with 5.degree. spread (t.r.)
(t.r.) Texture strength and orientation for route A as a function
of the number of passes and initial texture ROUTE A (STRONG INITIAL
TEXTURE) Original (10.9 54.7 45):(-111)<1-23>:16% 21.7 17.02
(N = 0) (105 26.5 0):(-102)<-28-1>:14% (110 24
26.5):(-215)<-5-5-1>:9.3% N = 1 (119 26.5
0):(-102)<-2-4-1>:17.62% 10.9 10.9 (346 43.3
45):(-223)<2-12>:7.62% N = 2 (138 26.5
0):(-102)<-2-2-1>:8.66% 6.1 6.9 (31 36.7
26.5):(-213)<-3-64>:8.6% N = 3 (126.7 26.5
0):(-102)<-2-3-1>:7.45% 5.79 5.45 (21 36.7
26.5):(-213)<2-43>:6.1% N = 4 (26.5 36.7
26.5):(-213)<2-64>9.42% 4.82 6.55 (138 26.5
0):(-102)<-2-2-1>:4.62% 169 15.8 45):(-115)<-32-1>:4.-
32% N = 6 (126.7 26.5 0):(-102)<-2-3-1>:6.66% 3.94 5.61 (228
33.7 0):(-203)<-34-2>:5.8% (31 36.7
26.5):(-213)<3-64>:3.42% N = 8 (0 35.2
45):(-112)<1-11>:3.1% 2.05 3.5 (180 19.4
45):(-114)<-22-1>:3.06% (31 25.2 45):(-113)<1-52>:2.2-
% ROUTE A (WEAK INITIAL TEXTURE) Original (80 25.2
45):(-113)<8-11 1>:4.3% 2.6 3.2 (N = 0) Large spreading
around (106) (119) N = 1 (0 46.7 45):(-334)<2-23>:5.8% 4.02
6.3 (222 26.5 0):(-102)<-22-1>:5% (128 18.4
0):(-103)<-3-4-1>4.01% N = 2 (126.7 26.5
0):(-102)<-2-3-1>:6.22% 4.4 6.8 (26.5 48.2
26.5):(-212)<1-22>:5.4% (162 13.2 45):(-116)<-42-1>5.-
4% N = 4 (226 36.7 26.5):(-213)<-12-1>4.85% 3 5.1 (233 26.5
0):(-102)<-23-1>:4.63% (136 19.5
45):(-114)<-40-1>:4.54% (26.5 36.7 26.5):(-213)<2-64>-
3.7% Texture strength and orientation for route B as a function of
the number of passes and initial texture ROUTE B (STRONG INITIAL
TEXTURE) Original (10.9 54.7 45):(-111)<1-23>:16.4% 21.7
17.02 (N = 0) (105 26.5 0):(-102)<-2-8-1>:14% (110 24
26.5):(-215)<-5-5-1>:9.- 3% N = 1 (119 26.5
0):(-102)<-2-4-1>:17.62% 10.9 10.9 (346 43
45):(-223)<2-12>:7.62% N = 2 (0 48
26.5):(-212)<425>P24.24% 17.27 14.02 (216 15.8
45):(-115)<-24-1>:8.07% (138 26.5 0):(-102)<-2-2-1>:5-
.04% N = 3 (260 36 74): (-2 7 10)<94-1>:15.49% 7.3 9.1 (118
18.4 90):(013)<-63-1>:5.23% N = 4 (96 36 16):(-7 2
10)<-6-15-1>:12% 6 9.77 (187 15.6
26.5):(-21-8)<-32-1>- ;:8.05% N = 6 (230.5 14
0):(-104)<-45-1>:12.46% 6.3 8.45 (100 36 16):(-7 2
10)<-4-9-1>:10.2% N = 8 (230.5 14
0):(-104)<-45-1>:9.19% 4.9 6.99 (180 13.2
45):(-116)<-33-1>:8.21% (100 36 16):(-7 2
10)<-4-9-1>:7.48% Texture strength and orientation for route
C as a function of the number of passes and initial texture ROUTE C
(STRONG INITIAL TEXTURE) Original (10.9 54.7
45):(-111)<1-23>:16.4% 21.7 17.02 (N = 0) (105 26.5
0):(-102)<-2-8-1>:14% (110 24 26.5):(-215)<-5-5-1>:9.-
3% N = 1 (119 26.5 0):(-102)<-2-4-1>:17.62% 10.9 10.9 (346 43
45):(-223)<2-12>:7.62% N = 2 (0 34.5
14):(-416)<4-13>:43.3% 48.9 25.9 (221.8 265 0):(-102)<-2 2
-1>:10.5% N = 3 (254 148.4 0):(-103)<-3 11 -1>:7.5% 5.2
6.05 (111.5 46.5 18.4):(-313)<-2-3-1>: 6.6% N = 4 (130 36.9
10):(-304)<-4-6-3>:15.05% 7.95 13.3 N = 5 Large spreading 2.4
3.3 (270 14 0):(-104)<010>:4.66% (26.5 48
26.5):(-212)<1-22):2.54% N = 6 (110 36 16):(-7 2
10)<-5-8-2>:11.6% 6.32 9.3 (234 33.7
0):(-203)<-35-2>:5.7% N = 7 Large spreading 2.35 3.15 (242
18.4 0):(-103)<-36-1>:4.66% (188 11.4
45):(-117)<-34-1>3.36% N = 8 (136.5 18.4
0):(-103)<-331>14.71% 12.9 11 (257 45 0):(-101)<-8 49
-8>:8.75% Texture strength and orientation for route D as a
function of the number of passes and initial texture ROUTE D
(STRONG INITIAL TEXTURE) Original (10.9 54.7
45):(-111)<1-23>16.4% 21.7 17.02 (N = 0) (105 26.5
0):(-102)<-2-8-1>14% (110 24 26.5):(-215)<-5-5-1>9.3% N
= 1 (119 26.5 0):(-102)<-2-4-1>17.62% 10.9 10.9 (346 43
45):(-223)<2-12>7.62% N = 2 (0 48
26.5):(-212)<425>24.24% 17.27 14.02 (216 15.8
45):(-115)<-2 4 -1>:8.07% (138 26.5 0):(-102)<-2-2-1>-
5.04% N = 3 (197 20.4 26.5):(-216)<-22-1>9.57% 3.91 6.67 all
other components < 3% N = 4 (222 26.5
0):(-102)<-22-1>:13.34% 6.346 7.36 all other components <
3.8% N = 6 (223.5 18.5 0):(-103)<-33-1>:7.4% 2.72 4.26 all
other components < 2.5% N = 8 (222 26.5
0):(-102)<-22-1>:3.42% 1.9 3.01 all other components < 3%
ROUTE D (WEAK INITIAL TEXTURE) Original (80 25.2 45):(-113)<-8
-11 1>:4.3% 2.6 3.2 (N = 0) Large spreading around (106) (119) N
= 1 (0 46.7 45):(-334)<2-23>:5.8% 4.02 6.3 (221 26.5
0):(-102)<-22-1>:5% (128 18.4 0):(-103)<-3-4-1>:4.01% N
= 2 (241 26.5 0):(-102)<-24-1>:12.72% 5 6.7 (26.5 48.2
26.5):(-212)<1-22>:4.1% N = 3 (197 20..about.
26.5):(-216)<-22-1>:8.8% 3.5 6.44 (26.5 48.2
26.5):(-212)<1-22>:3.9% N = 4 (221.8 26.5
0):(-102)<-22-1>:7.2% 3 5.3 (26.5 48.2
26.5):(-212)<1-22>:3.1%
[0066]
2TABLE 2 N Annealing at (150 C., 1 h) Annealing at (225 C., 1 h)
Annealing at (300 C., 1 h) Major texture orientations for route A
in function of number of passes N and annealing temperature ROUTE A
(STRONG INITIAL TEXTURE) Notations: Euler angles
(.alpha..beta..gamma.):{xyz} <uvw>: % total volume with
5.degree. spread 1 (43 47 22):(-525)<1-32>: (35 48
25):(-212)<1- (76 29.5 45):(-225)<-5- 10.4% 22>:13.15%
71>:9.3% (110 26.5 0):(-102)<-2-6- (114 22
10):(-102)<-2-4- (141 37 0):(-304)<-4- 1>:8.04% 1>:9.3%
4-3>:6.6% (130 24 18.4):(-317)<-3- 2-1>:7.15% 2 (105 22
0):(-205)<-5 20- (136 18.4 0):(-103)<- (354 18.4 0):(-103)
2>: 9.21% 3-3-1>:20.9% <913>:7.74% (155 19.5
45):(-114)<-31- (112 19 18.4):(-319) (315 11.5 45):(-117)
1>:7.83% <-5-6-1>:20.2% <701>:7.38% (31 36.7
45):(-213)<3- (90 7 0):(-108)<0-10>: 64>: 6.88% 6.7% 3
(110 36 16):(-7 2 10)<-4- (110 45 0):(-101)<-1- Large
spreading around 9-2>:15.2% 4-1>:16.85% (117), (100) (233
26.5 0):(-102)<-23- (290 45 0):(-101) All components < 4%
1>:7.35% <141>:11.5% 4 (129 18 26):(-217)<-1-5- (124 25
14):(-419)<- (110 25.2 45):(-113)<- 1>:11.73%
3-3-1>:12.4% 6-3-1>:6.87% (35 37 26.5):(-213)<2- (38 36.7
26.5):(-213) (318 25.2 45):(-113) 53>:11.2% <3-95>:7.5%
<301>:5.1% 6 (180 19.5 45):(-114)<-22- Large spreading
(46.7 19.5 45):(-114) 1>:5.5% All components < 5% <-1-17
4>:9% (135 10 0):(-106)<-6-6- All components < 4.9%
1>:4% (0 46.7 45):(-334)<2-23>: 3.95% 8 Large spreading
around (44 36 26.5):(-213) (152 32 0):(-508)<-8- (315),
<2-63>:7.94% 5-5>:6.4% (104) (136 18.4 0):(-103)<- All
components < 3% All components < 4% 3-3-1>:6.17% Major
texture orientations for route B in function of number of passes N
and annealing temperature ROUTE B (STRONG INITIAL TEXTURE)
Notations: Euler angles (.alpha..beta..gamma.):{xyz} <uvw>: %
total volume with 5.degree. spread 1 (43 47 22):(-525)<1-32>:
(35 48 25):(-212)<1-22>: (76 29.5 45):(-225)<- 10.4%
13.15% 5-71>:9.3% (110 26.5 0):(-102)<-2-6- (114 22
10):(-102)<-2-4- (141 37 0):(-304)<4- 1>:8.04% 1>:9.3%
4-3>:6.6% (130 24 18.4):(-317)<-3- 2-1>:7.15% 2 (215 20
26.5):(-216)<-36- (112 34 0):(-203)<-3-9- (221 26.5
0):(-102)<- 2>:35% 2>:16% 22-1>:13.3% (270 13.2
45):(-116) (16 54.7 45):(--111)<1- (109 14 0):(-104)<-4-
<110>: 34>:8.88% 12-1>:12% 16% 3 (148 19 79):(-1 5
15)<- (10 45 10):(-616)<3- (0 48 26.5):(-212)<4-
55-2>:17.5% 13>:5.7% 25>:6% (90 16 45):(-115)<-1- (235
14 0):(-104)<46- (222 41 45):(-223) 10>: 1>:4.53%
<03-2>:5.8% 6.9% Large spreading (19.5 45 0):(-101)
<2-12>:5.4% 4 (127 26.5 0):(-102)<-2-3- (230 14
0):(-104)<-45- Large spreading 1>:5.9% 1>:6.23% around
(107) (115) (242 14 0):(-104)<-4 8 - All components < 3%
1>: 6 (180 19.5 45):(-114)<-22- Large spreading (46.7 19.5
45):(-114) 1>:5.5% All components < 5% <-1-17 4>:9%
(135 10 0):(-106)<-6-6- All components < 4.9% 1>:4 (0 46.7
45):(-334)<2- 23>:3.95% 8 Large spreading around (44 36
26.5):(-213)<2- (153 32 0):(-508)<-8- (315), (104)
63>:7.94% 5-5>:6.4% All components < 4% (136 18.4
0):(-103)<-3- All components < 3% 3-1>:6.17% Major texture
orientations for route C in function of number of passes N and
annealing temperature ROUTE C (STRONG INITIAL TEXTURE) Notations:
Euler angles (.alpha..beta..gamma.):{xyz} <uvw>: % total
volume with 5.degree. spread 1 (43 47 22):(-525)<1-32>: (35
48 25):(-212)<1- (76 29.5 45):(-225)<-5- 10.4% 22>:13.15%
71>:9.3% (110 26.5 0):(-102)<-2- (114 22 10):(-102)<-2-
(141 37 0):(-304)<-4-4- 6-1>:8.04% 4-1>:9.3% 3>:6.6%
(130 24 18.4):(-317)<-3- 2-1>:7.15% 2 (191 16
45):(-115)<-23- (99 46 14):(-414)<-3-8- Large spreading
around 1>:8.77% 1>:20.9% (100) (156 26.5 0):(-102)<-2-
(289 45 0):(-101)<141>: All components < 3.8%
1-1>:6.68% 15.22% 3 (119 26.5 0):(-102)<-2- (106 29
26.5):(-214)<- (194 14 0):(-104)<-41- 4-1>:28.4%
5-6-1>:19.5% 1>:6.1% (26.5 48 26.5):(-212)<1- (103 31
34):(-326)<-6- (163 18.4 0):(-103)<-3- 22>:9.74%
6-1>:18.7% 1-1>:5.85% (42 46.5 18.4):(-313)
<1-32>:8.83% 4 105 38 18.5):(-314)<-3- Large spreading
around Large spreading around 5-1>:10.2% (302) and (225) (100)
(105) (116) Other components < 5.3% All components < 2.8% All
components < 4.1% 5 (103 32 18.4):(-3 1 5)<- (127 26.5
0):(-102)<-2- Large spreading around 4-7-1>:19% 3-1>:7%
(106) (115) (22 38 18.4):(-314)<1- All components < 3.7%
11>5.6% 6 (61 46 14):(-414)<1- Large spreading around (80 25
45):(-113)<-8-11 83>:11.82% (101) and (334) 1>:4.3% (155
21 18.4):(-318)<- All components < 4% All components < 3%
22-1>:7.94% 7 (104 36 16):(-7 2 10)<- (125 37
0):(-304)<-47- Large spreading around 3-6-1>:29% 3>:7.8%
(100) (105) (203) (26.5 48 26.5):(-212)<1- (305 45
0):(-101)<121>: All components < 2.9% 22>:7.6% 5.82% 8
(104 47 22):(-525)<-3-5- (106 38 18.4):(-314)<- Large
spreading around 1>:15.36% 3-5-1>4.64% (100) (105) (112)
(203) All components < 3.2% All components < 2.7% Major
texture orientations for route D in function of number of passes N
and annealing temperature ROUTE D (STRONG INITIAL TEXTURE)
Notations: Euler angles (.alpha..beta..gamma.):{xyz} <uvw>: %
total volume with 5.degree. spread 1 (43 47 22):(-525)<1-32>:
(35 48 25):(-212)<1-22>: (76 29.5 45):(-225)<- 10.4%
13.15% 5-71>:9.3% (110 26.5 0):(-102)<-2-6 (114 22
10):(-102)<-2-4- (141 37 0):(-304)<-4- 1>:8.04% 1>:9.3%
4-3>:6.6% (130 24 18.4):(-317)<-3- 2-1>:7.15% 2 (215 21
26.5):(-216)<-36- (112 34 0):(-203)<-3-9- (222 26.5
0):(-102)<- 2>:35% 2>:16.45% 22-1>:13.3% (270 13
45):(-116)<110>: (16 54.7 45):(-111)<1- (109 14
0):(-104)<-4- 16% 34>:8.88% 12-1>:12% (162 9
45):(-119)<- 63-1>:9.6% 3 (337 50 34):(--(323) (168 20
25):(-216)<-82- (150 16 45):(-115)<115)<-
<101>:12.2% 3>:10.35% 41-1>:5.6% (215 47
45):(-334)<0 4 - (102 18.4 0):(-103)<-3- (198 18.4
0):(-103)<- 3>:9.75% 16-1>:9.32% 31-1>:5.2% (241 26.5
0):(-102)<-24- (162 13 45):(-116)<-42- 1>:7.02%
1>:6.44% 4 (233 26.5 0):(-102)<-23- Large spreading Large
spreading 1>9% All components < 3.6% around (105) (116) All
other components < 4% All components < 3.9% 6 (224 18.4
0):(-103)<-33- (224 18.4 0):(-103)<-33- Large spreading
1>:8.29% 1>:5.49% around (106) and All other components (109
18.4 0):(-103)<-3- (113) <3.8% 9-1>:4.4% All components
< 2.9% 8 (222 27 0):(-102)<-22- (205 21 18.4):(-138)<-
(222 26.5 0):(-102)<- 1>:8.58% 22-1>:11.44% 22-1>:8.58%
All components < 4% (233 26.5 0):(-102)<-23- (38 16
45):(-115)<1- 1>:10.74% 92>:5.55%
[0067] (1) The number of ECAE passes permits the control of texture
strength. The increase of the number of passes is an efficient
mechanism of randomizing texture. There is an overall decrease of
texture strength evidenced by the creation of new orientations and,
more importantly, the large spreading of orientations around the
major components of the texture as evidenced in FIG. 4. FIG. 4 is
an illustration of (200) pole figures for Al with 0.5 wt. % Cu
alloys processed 2, 4 and 8 passes of route D (FIG. 5) and shows
spreading of orientations as "N" increases. This phenomenon is more
or less effective depending on the investigated route and/or
annealing treatment. For example in the as-deformed state, routes B
and C result in somewhat higher textures than routes A and D (FIG.
5 and Table 1). FIG. 5 is a graph that shows the influence of ECAE
deformation route and strength on texture formation as a function
of number of ECAE passes. For medium to very strong starting
textures, two main areas can be distinguished in the as-deformed
state(FIG. 5).
[0068] Between passes 1 and 4 (with a tool angle of 90.degree.),
very strong to medium textures are obtained. In the investigation
of Al.5Cu, for example, the OD index ranges from more than 7 times
random to more than 48 times random which corresponds to maximum
intensities of the ODF between 3000 mrd (30 times random) and more
than 20000 mrd (200 times random).
[0069] For more than 4 passes (with a tool angle of 90.degree.),
medium-strong to very weak textures close to random are created. In
the case of Al.5Cu alloys, OD index varies from around 11 times
random to less than 1.9 times random depending on the route, which
corresponds to maximum intensities of the ODF between 7000 mrd (70
times random) and around 800 mrd (8 times random).
[0070] The two main domains are maintained after subsequent
annealing, as shown in the graphs of FIGS. 6, 7, 8 and 9. However
for some ECAE deformation routes (for example route B and C in the
case of Al.5Cu), additional heating can give a strong texture, as
discussed below. The existence of these two areas is a direct
consequence of the microstructural changes occurring in the
material during intensive plastic deformation. Several types of
defects (dislocations, microbands, shear bands and cells and
sub-grains inside these shear bands) are gradually created during
the 3 to 4 ECAE passes (for a tool angle of 90.degree.). The
internal structure of materials is divided into different shear
bands while increasing the number of passes. After 3 to 4 ECAE
passes, a mechanism termed dynamic recrystallization occurs and
promotes the creation of sub-micron grains in the structure. As the
number of passes increases these grains become more and more
equiaxed and their mutual local mis-orientations increase giving
rise to a higher number of high angle boundaries in the structure.
The very weak and close to random textures that are created are a
consequence of three major characteristics of the dynamically
recrystallized microstructures: the presence of high internal
stresses at the grain boundaries, the large number of high angle
boundaries and the very fine grain size with a large grain boundary
area (usually of the order of about 0.1-0.5 .mu.m).
[0071] (2) The ECAE deformation route permits control of the major
orientations of the texture. Depending on the route, different
shear planes and directions are involved at each pass (see FIG. 5
and Tables 1 and 2). Therefore shear bands of different
orientations are created in the structure. For some routes these
shear bands always intersect each other in the same way; for other
routes new families are constantly introduced at each pass (Tables
1 and 2). All these options allow changes to the major components
or orientations between each pass. The effect is particularly
strong for a small number of passes before the advent of dynamic
recrystallization, as discussed above. An important application
exists in the possibility to create different types of strong
textures already in the as-deformed state for a limited number of
ECAE passes.
[0072] (3) Additional annealing has an important influence on both
the major texture orientations and strength (see FIGS. 6, 7, 8, 9
and Table 2).
[0073] For annealing temperatures below the static
recrystallization, a change in both texture strength and main
orientation is observed. This effect can be particularly strong for
a low number of passes (less than about 4 passes) leading to
remarkable migrations of major orientations accompanied with either
a decrease or increase of texture strength. Such changes can be
attributed to the instability of microstructural defects which are
implemented in the crystal structure. Complex mechanisms such as
recovery and sub-grain coalescence explain partly the observed
phenomena. For dynamically recrystallized ultra-fine structure
(after usually 4 passes) smaller modifications are encountered.
They are usually associated with the transition from a highly
stressed to a more equilibrium micro structure.
[0074] For annealing temperatures close to the beginning of static
recrystallization, the same over-all results as in the above case
are found. However, it is important to note that new and different
textures than for low temperature annealing can be obtained,
especially for a low number of ECAE passes (Table 2). This is due
to static recrystallization which creates new grains with new
orientations by diffusion mechanisms.
[0075] For annealing temperatures corresponding to developed stages
of static recrystallization (full static recrystallization),
textures tend to be weakened (as shown in FIGS. 6, 7, 8, 9 and
Table 2). This is particularly true after 3 or 4 ECAE passes where
very weak and almost random textures are created. These textures
are characterized by four, six or eight fold symmetry with a higher
number of cube (<200>) components.
[0076] Additional textural analysis of ECAE deformed Al and 0.5 wt.
% Cu is shown in the pole figure described in FIG. 10. In this case
the sample was given an initial thermochemical treatment of casting
plus homogeneous plus hot forging plus cold rolling (.about.10%)
plus two ECAE passes via route C plus annealing (250.degree. C., 1
hour). The recrystallized microstructure had grain size of 40-60
.mu.m and strong texture along {-111}<2-12>,
{012}<-130>, {-133}<3-13>. The result shows two ECAE
passes (C) plus static recyrstalization permits removal of the very
strong (220) textural component of the as-forged condition.
[0077] By taking into account all the foregoing, results show that
intermediate annealing between each pass provides several
additional and significant opportunities to adjust desired
textures. Two options are available:
[0078] A. Intermediate annealing either at low temperature or just
at the beginning of static recrystallization after a low number of
passes (N<4) can give strong textures with new orientations
after subsequent deformation with or without annealing.
[0079] B. Intermediate annealing in the case of full static
recrystallization after a low or high number of passes can lead
more easily to very weak textures after subsequent deformation with
or without annealing.
[0080] It is also possible to repeat intermediate annealing several
times in order to enhance the effects described above.
[0081] (4) Starting texture has also a strong influence on both
texture and strength especially after a limited number of passes
(usually after 1 to 4 passes). For a higher number of passes the
ECAE deformation is very large and new mechanisms are taking place
which lessen the magnitude of the influence of the starting
texture. Two situations are noted (FIG. 5 and Table 1 for route A
and D):
[0082] A. For a strong to medium starting textures, after further
deformation with or without annealing, it is possible to obtain
very strong to medium textures before 4 passes and strong-medium to
very weak textures after approximately 4 passes according to the
results described in paragraph 1, 2 and 3.
[0083] B. For medium to very weak starting textures it will be more
difficult to obtain very strong to strong textures at least in the
as-deformed state. Weak starting textures are more likely to
enhance and promote weak to random textures after ECAE deformation
with or without annealing (Table 1).
[0084] (5) Second phase particles have a pronounced effect on
texture. Large (>1 .mu.m) and non-uniformly distributed
particles are not desired because they generate many problems such
as arcing during sputtering. Very fine (>1 .mu.m) and uniformly
distributed second phase particles are of particular interest and
offer many advantages. Firstly, they tend to create a more even
stress-strain state during ECAE deformation. Secondly, they
stabilize the already ECAE-deformed microstructure in particular
after further annealing. In this case particles pin grain
boundaries making them more difficult to change. These two major
effects evidently affect the texture of materials. Especially:
[0085] for a small number of passes (<4 passes), the effects
described previously in sections (1) to (4) can be enhanced due to
the presence of second phase particles in particular for strong
textures.
[0086] for a large number of passes, second phase particles are
effective in promoting the randomization of texture.
[0087] In order to take advantage of the possibilities offered by
the ECAE technique in terms of texture control, three types of
results can be achieved:
[0088] A. Materials (sputtering targets) with strong to very strong
(ODF>10000 mrd) textures. In particular this can be obtained for
a small number of passes with or without subsequent annealing or
intermediate annealing. A strong starting texture is a factor
favoring the creation of strong textures. For example in the case
of A1.5Cu alloy Table 1 gives all the major components of
orientations which were created for different deformation routes
(A,B,C,D) between 1 and 4 passes. The as-deformed state as well as
deformation followed either by low temperature annealing
(150.degree. C., 1 h) or by annealing at the beginning of static
recrystallization (225.degree. C., 1 h) or after full
recrystallization (300.degree. C., 1 h) are considered in this
table. The original texture is displayed in FIG. 7. It is important
to note that in most cases new types of textures have been found.
Not only {200} and {220} textures are present but also {111},
{140}, {120}, {130}, {123}, {133}, {252} or, for example, {146}.
For strong textures, one or two main components are usually
present.
[0089] B. Material (sputtering targets) with weak to close to
random textures with an ultra-fine grain size less than 1 .mu.m.
Whatever the route this can be obtained after more than 3 to 4 ECAE
passes followed or not by annealing or intermediate annealing at a
temperature below the beginning of recrystallization temperature. A
very weak starting texture is a factor favoring the creation of
close to random textures.
[0090] C. Statically recrystallized materials (sputtering targets)
with weak to close to random textures with a fine grain size above
approximately 1 .mu.m. Whatever the route this can be obtained
after more than 3 to 4 ECAE passes followed by annealing or
intermediate annealing at a temperature above the beginning of
recrystallization temperature. A very weak starting texture is a
factor favoring the creation of close to random textures.
[0091] Another embodiment of the invention is an apparatus for
performing the process to produce targets. The apparatus (FIGS. 11,
11A and 11B) includes die assembly 1, die base 2, slider 3, punch
assembly 4,6 hydraulic cylinder 5, sensor 7, and guide pins 11.
Also the die is provided with heating elements 12. Die assembly 1
has a vertical channel 8. A horizontal channel 9 is formed between
die assembly 1 and slider 3. The die is fixed at table 10 of press,
punch assembly 4, 6 is attached to press ram. In the original
position a-a the forward end of slider 3 overlaps channel 1, punch
4 is in a top position, and a well lubricated billet is inserted
into the vertical channel. During a working stroke punch 4 moves
down, enters channel 8, touches the billet and extrudes it into
channel 9. Slider 3 moves together with billet. At the end of
stroke the punch reaches the top edge of channel 9 and then returns
to the original position. Cylinder 5 moves the slider to position
b-b, releases the billet, returns the slider to the position a-a
and ejects the processed billet from the die. The following
features are noted:
[0092] (a) During extrusion slider 3 is moved by hydraulic cylinder
5 with the same speed as extruded material inside channel 9. To
control speed, the slider is provided with sensor 7. That results
in full elimination of friction and material sticking to the
slider, in lower press load and effective ECAE;
[0093] (b) Die assembly 1 is attached to die base 2 by guide pins
11 which provide free run 6. During extrusion the die assembly is
nestled to the base plate 2 by friction acted inside channel 8.
When the punch returns to the original position, no force acts on
the die assembly and slider, and cylinder 3 can easily move the
slider to position b-b and then eject the billet from the die.
[0094] (c) Three billet walls in the second channel are formed by
the slider (FIG. 11A) that minimizes friction in the second
channel.
[0095] (d) The side walls of the second channel in the slider are
provided with drafts from 5.degree. to 12.degree.. In this way the
billet is kept inside the slider during extrusion but may be
ejected from the slider after completing extrusion. Also, thin
flash formed in clearances between the slider and die assembly may
be easily trimmed.
[0096] (e) Die assembly is provided with heater 12 and springs 13.
Before processing, springs 13 guarantee the clearance 5 between die
assembly 1 and die base 2. During heating this clearance provides
thermoisolation between die assembly and die base that results in
short heating time, low heating power and high heating
temperature.
[0097] The apparatus is relatively simple, reliable and may be used
with ordinary presses.
* * * * *