U.S. patent application number 11/148655 was filed with the patent office on 2006-04-20 for amorphous alloy excelling in fatigue strength.
Invention is credited to Yoshihiko Yokoyama.
Application Number | 20060081310 11/148655 |
Document ID | / |
Family ID | 35455197 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060081310 |
Kind Code |
A1 |
Yokoyama; Yoshihiko |
April 20, 2006 |
Amorphous alloy excelling in fatigue strength
Abstract
An amorphous alloy having a composition represented by the
general formula: X.sub.aM.sub.bAl.sub.c (wherein X represents at
least one element selected from the group consisting of Zr and Hf,
M represents at least one element selected from the group
consisting of Ni, Nb, Cu, Fe, Co, and Mn, and a, b, and c represent
such atomic percentages as respectively satisfy
25.ltoreq.a.ltoreq.85, 5.ltoreq.b.ltoreq.70, and 0<c.ltoreq.35)
and containing an amorphous phase in the range of 50-100% in a
volumetric ratio contains hydrogen incorporated therein. Preferably
the hydrogen is present in the amorphous alloy in an amount of
0.005-10% of the amorphous alloy in a weight ratio.
Inventors: |
Yokoyama; Yoshihiko;
(Himeji-shi, JP) |
Correspondence
Address: |
Michael S. Leonard;EVEREST INTELLECTUAL PROPERTY LAW GROUP
P.O. Box 708
Northbrook
IL
60065
US
|
Family ID: |
35455197 |
Appl. No.: |
11/148655 |
Filed: |
June 9, 2005 |
Current U.S.
Class: |
148/403 |
Current CPC
Class: |
C22C 45/10 20130101 |
Class at
Publication: |
148/403 |
International
Class: |
C22C 45/00 20060101
C22C045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 10, 2004 |
JP |
2004-172253 |
Claims
1. An amorphous alloy having a composition represented by the
following general formula and containing an amorphous phase in a
volumetric ratio of 50-100%, the improvement which comprises
hydrogen incorporated therein: X.sub.aM.sub.bAl.sub.c wherein X
represents at least one element selected from the group consisting
of Zr and Hf, M represents at least one element selected from the
group consisting of Ni, Nb, Cu, Fe, Co, and Mn, and a, b, and c
represent such atomic percentages as respectively satisfy
25.ltoreq.a.ltoreq.85, 5.ltoreq.b.ltoreq.70, and
0<c.ltoreq.35.
2. The amorphous alloy according to claim 1, wherein said hydrogen
is present in said amorphous alloy in an amount of 0.005-10% of
said amorphous alloy in a weight ratio.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to an amorphous alloy which exhibits
high hardness and high strength, excels in working characteristics,
has high resistance to corrosion and high fatigue strength, and
further excels in vibration-damping properties.
[0003] 2. Description of the Prior Art
[0004] Since an amorphous alloy being also called metal glass
generally has such higher strength as the tensile strength about 3
times of a stainless steel and about twice of a titanium alloy and
exhibits high resistance to corrosion and low Young's modulus, it
has become of major interest as an industrial material.
[0005] Among the amorphous alloys heretofore known in the art, the
amorphous alloys of Zr,Hf-M-Al system (M=Ni, Cu, Fe, Co, Mn) having
a wide temperature width of a supercooled liquid region, which is a
temperature width between a glass transition temperature (Tg) and a
crystallization temperature (Tx), and excelling in various
properties such as high hardness, high strength, high heat
resistance, and high corrosion resistance are known as the
amorphous alloys having excellent working characteristics (for
example, see JP 3-158446,A).
[0006] However, the above-mentioned amorphous alloys and the metal
glass which is now generally studied exhibit low fatigue strength
and thus are not suitable as a material which is used in a place to
be subjected to repeated stress for a long period of time. Further,
since the metal glass is microscopically a non-defective material
containing therein no "dislocation" or the like defects which are
contained in a common crystalline metal, once vibration is applied
to the material, the vibration will continue for a long period of
time because the vibration will not be obstructed by "dislocation"
etc. That is, the metal glass has such a problem that the
"vibration-damping properties" thereof are poor.
SUMMARY OF THE INVENTION
[0007] It is, therefore, an object of the present invention to
provide amorphous alloys which, while retaining the excellent
properties of the above-mentioned Zr-based and Hf-based amorphous
alloys of exhibiting high hardness and high strength, excelling in
working characteristics, and having high corrosion resistance,
further exhibit improved fatigue strength and excel in the
vibration-damping properties.
[0008] To accomplish the object mentioned above, the present
invention provides an amorphous alloy having a composition
represented by the following general formula and containing an
amorphous phase in a volumetric ratio of 50-100%, characterized in
that it contains hydrogen incorporated therein:
X.sub.aM.sub.bAl.sub.c wherein X represents at least one element
selected from the group consisting of Zr and Hf, M represents at
least one element selected from the group consisting of Ni, Nb, Cu,
Fe, Co, and Mn, and a, b, and c represent such atomic percentages
as respectively satisfy 25.ltoreq.a.ltoreq.85,
5.ltoreq.b.ltoreq.70, and 0<c.ltoreq.35.
[0009] Since the amorphous alloy of the present invention uses as a
base material the amorphous alloy having the composition
represented by the above-mentioned general formula and exhibiting a
temperature width of a supercooled liquid region which is a
temperature width between a glass transition temperature (Tg) and a
crystallization temperature (Tx) and further contains hydrogen
incorporated therein, it remarkably exhibits the following features
and effects besides such excellent characteristic as high hardness,
high strength, high heat resistance, and high corrosion resistance,
[0010] greatly improved strength, thereby bringing about the
long-term reliability as a material, and [0011] improved
vibration-damping properties, as a result, even if vibration is
added thereto, the vibration attenuates promptly and the sound
simultaneously generated becomes small.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Other objects, features, and advantages of the invention
will become apparent from the following description taken together
with the drawings, in which:
[0013] FIG. 1 is a fragmentary cross-sectional side view
schematically illustrating one example of a vacuum melting and
injection-molding apparatus to be used for the production of a
metal glass article of the present invention, depicting a matrix
alloy supply process;
[0014] FIG. 2 is a fragmentary cross-sectional side view
schematically illustrating the apparatus shown in FIG. 1, depicting
a process of transferring a matrix alloy to a heat-melting
section;
[0015] FIG. 3 is a fragmentary cross-sectional side view
schematically illustrating the apparatus shown in FIG. 1, depicting
an injection process;
[0016] FIG. 4 is a fragmentary cross-sectional side view
schematically illustrating the apparatus shown in FIG. 1, depicting
a molded article extraction process;
[0017] FIG. 5 is a plan view illustrating a matrix alloy cassette
section of a matrix alloy feeding apparatus used in the apparatus
shown in FIG. 1;
[0018] FIG. 6 is a graph showing the changes in fatigue stress of
metal glass test pieces (Zr.sub.50Cu.sub.40Al.sub.10) containing
hydrogen or containing no hydrogen in relation to the number of
cycles;
[0019] FIG. 7 is a graph showing the changes in fatigue stress of
metal glass test pieces (Zr.sub.60Cu.sub.30Al.sub.10) containing
hydrogen or containing no hydrogen in relation to the number of
cycles;
[0020] FIG. 8 is a graph showing the changes in fatigue stress of
metal glass test pieces (Zr.sub.50Cu.sub.30Ni.sub.10Al.sub.10)
containing hydrogen or containing no hydrogen in relation to the
number of cycles; and
[0021] FIG. 9 is a graph showing the changes in fatigue stress of
metal glass test pieces (Zr.sub.55Cu.sub.30Ni.sub.5Al.sub.10)
containing hydrogen or containing no hydrogen in relation to the
number of cycles.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The amorphous alloy of the present invention uses as a base
material the amorphous alloy having the composition represented by
the above-mentioned general formula and contains hydrogen
incorporated therein. Since the hydrogen present in the metal glass
has a small atomic radius (0.3 .ANG.; oxygen and nitrogen: 0.74
.ANG.) as compared with other metal atoms, it can move in the metal
glass. As a result, it will bring about such an effect that when a
crack caused by a fatigue fracture propagates, hydrogen
concentrates in a tip portion of the fatigue crack and this portion
hardens, thereby stopping propagation of the fatigue fracture.
[0023] A method of incorporating hydrogen into the metal glass may
be suitably performed by adding hydrogen gas in an inactive
atmosphere to be used in the preparation of a matrix alloy
(preform) from a raw molten metal.
[0024] Since Zr and Hf which are the main raw materials of metal
glass tend to be easily oxidized, raw materials should be melted in
an inactive atmosphere. In accordance with the present invention,
by using an inactive atmosphere (inert gas) containing hydrogen gas
mixed therein when this preform is prepared, it is possible to
uniformly mix hydrogen into a preform and eventually to manufacture
a metal glass article containing a few amount of hydrogen. Since
the hydrogen-containing metal glass produced by this method
exhibits considerably improved fatigue strength and
vibration-damping properties, it is possible to provide an
amorphous alloy material which is reliable as a material to be put
in practical use.
[0025] The unduly low content of hydrogen in the metal glass is not
desirable because hydrogen can concentrate in a tip portion of a
crack caused by a fatigue fracture only with difficulty due to its
unduly low content and this portion will not easily harden and, as
a result, it will be hardly possible to stop propagation of the
fatigue fracture. Conversely, if the hydrogen content is too high,
since the proportion of bonding between Zr or Hf and a hydrogen
atom will increase, the hydrogenated Zr or Hf will be produced
consequently, which will result in an undesirable effect of making
the material brittle. Generally, the content of hydrogen in metal
glass is properly in the approximate range of 0.005% to 10% in a
weight ratio, though it depends on the alloy composition.
[0026] Although the content of hydrogen in the metal glass is
mainly controlled by adjusting the amount of hydrogen gas in the
inert gas at the time of production of a matrix alloy, it is also
arbitrarily controllable by adjusting other conditions, such as a
melting period and a melting temperature. Further, it is preferable
that the content of oxygen in the metal glass be 1% or less in a
weight ratio during the manufacturing process. If the oxygen
content is unduly high so as to exceed 1%, the oxides contained in
the metal glass will increase, which will result in an undesirable
effect of making the material brittle. Furthermore, another reason
is that, if the oxygen content is high, the hydrogen concentrated
in the tip portion of the crack during the growth of fatigue
fracture and the oxygen contained in the metal glass will cause a
reaction and, as a result, the hydrogen which inhibits the
propagation of crack will be discharged out of the metal glass as
water.
[0027] As described above, the alloy which is a base material of
the amorphous alloy of the present invention has a composition
represented by the general formula: X.sub.aM.sub.bAl.sub.c (wherein
X represents at least one element selected from the group
consisting of Zr and Hf, M represents at least one element selected
from the group consisting of Ni, Nb, Cu, Fe, Co, and Mn, and a, b,
and c represent such atomic percentages as respectively satisfy
25.ltoreq.a.ltoreq.85, 5.ltoreq.b.ltoreq.70, and 0<c.ltoreq.35)
and contains an amorphous phase in a volumetric ratio of 50-100%.
Here, the reasons for limiting the atomic percentages a, b, and c
of elements X, M and Al to the above-mentioned ranges are that the
alloy will become amorphous only with difficulty in the composition
outside the above-mentioned range and that the alloy containing at
least 50% (volumetric ratio) of amorphous phase will be obtained
only with difficulty by an industrial quenching means using a
liquid quenching process, for example.
[0028] The amorphous alloy of the present invention may be produced
by preparing a hydrogen-containing matrix alloy having the
above-mentioned composition and rapidly solidifying its molten
metal by the liquid quenching process. This liquid quenching
process means a method of rapidly cooling the molten alloy. For
example, the amorphous alloy may be produced by the following
methods.
(1) Roll Process or Twin-Roll Method
[0029] In these techniques the cooling rate of about
10.sup.4-10.sup.6 K/sec. is attained. When a thin ribbon is
produced by this single roll method or the twin-roll method, the
molten metal of the above-mentioned composition containing hydrogen
incorporated therein in advance is injected through a nozzle hole
onto a roll made of, for example, copper or stainless steel and
having a diameter of 30-3,000 mm, which is rotating at a constant
rate in the approximate range of 300 to 10,000 r.p.m. By this
method, various thin ribbon materials having a width of about 1-300
mm and a thickness of about 5-500 .mu.m can be readily
obtained.
(2) In-Rotating-Liquid Spinning Method
[0030] When a thin wire material is produced by the in-rotating
liquid spinning method, the molten metal of the above-mentioned
composition containing hydrogen incorporated therein in advance is
injected through a nozzle hole under application of a back pressure
of argon gas into a liquid refrigerant layer having a depth of
about 10-100 mm and retained by centrifugal force in a drum
rotating at a rate of about 50-500 r.p.m. In such a manner, thin
wire materials may be readily obtained. In this technique, the
angle between the molten metal injected from a nozzle and the
liquid refrigerant surface is preferred to be in the approximate
range of 60.degree. to 90.degree. and the ratio of relative
velocity of the injected molten metal to the liquid refrigerant
surface is preferred to be in the range of 0.7 to 0.9.
(3) Die-Casting Method
[0031] When a metal glass article is produced by the die-casting
process, first a preform (matrix alloy) is prepared in advance in
an inactive atmosphere by uniformly melting the raw materials of
the above-mentioned metal glass by a melting method such as arc
melting, and this preform is subjected to die-casting to obtain a
final article of metal glass. At this time, by using the inert gas
containing hydrogen gas mixed therein as an inactive atmosphere, it
is possible to uniformly mix hydrogen into a preform to prepare a
hydrogen-containing preform. Subsequently, by using an apparatus as
disclosed in JP 2001-246451,A, for example, a preform is supplied
into a sleeve which is disposed so as to be reciprocated toward a
spruce of a metal mold provided with a cooling means. The preform
in the sleeve is melted by heating, injected into the metal mold by
means of a plunger slidably disposed in the above-mentioned sleeve
to effect casting, and then cooled in a supercooled region in the
metal mold to form the amorphous structure peculiar to metal glass.
Incidentally, the metal mold may be cooled or may not be cooled. As
the case may be, a molten metal may be properly cooled even if the
metal mold is heated, depending on the volume ratio of a cavity
size to a die set.
[0032] Besides the above methods, a thin film may be produced by
(4) a sputtering process. Further, a rapidly solidified powder may
be obtained by various atomizing methods such as, for example, (5)
a high-pressure gas atomizing process, or a spray process. In the
case of the sputtering process, by introducing hydrogen into a
melting atmosphere which is used for the preparation of a target
material by melting, it is possible to similarly produce the metal
glass thin film containing hydrogen incorporated therein. In the
atomizing process, by using hydrogen-containing gas as the gas to
be sprayed, it is possible to make a metal glass powder containing
hydrogen incorporated therein.
[0033] Whether the rapidly solidified alloy thus obtained is
amorphous or not can be known by checking the presence of the halo
pattern peculiar to an amorphous structure by an ordinary X-ray
diffraction method. Further, the amorphous structure is transformed
into a crystalline structure by heating to or above a specific
temperature (this temperature is called "crystallization
temperature").
[0034] Then, one example of the apparatus for the production of a
metal glass article by the die-casting process of the
above-mentioned processes will be described hereinbelow with
reference to the appended drawings.
[0035] FIG. 1 through FIG. 4 show one embodiment of the vacuum
melting and injection-molding apparatus for the production of an
metal glass article. In the Figures, reference numeral 1 denotes a
metal mold which comprises a stationary lower mold 2 and a movable
upper mold 3. The lower mold 2 having a sprue 4 is fixedly secured
to a main platen 7 having a circular opening 6 in the corresponding
portion and the gap between the lower mold 2 and the main platen 7
is sealed by a sealing member 8, such as an O-ring. A plurality of
tie bars 9 are set up on the main platen 7 in parallel with each
other and a stationary platen 10 is fixedly secured to the upper
end portions thereof. Although the number of tie bars 9 is four in
this embodiment, naturally it is not restricted to this number, but
also has the case of three or two bars. A movable platen 11
attached to these tie bars 9 is adapted to be reciprocated
vertically by means of mold-clamping cylinders 12 set on the
stationary platen 10. The movable upper mold 3 having cavities 5
formed in the parting surface which is brought into contact with
the stationary lower mold 2 is fixedly secured to the underside of
the movable platen 11 through the medium of a fixing member 13 and
a connecting member 14 (may be integral with the fixing member 13
as one piece). This movable upper mold 3 is reciprocated vertically
while following the vertical movement of the movable platen 11.
Incidentally, metal mold exhaust holes 15 are formed in the
predetermined positions of the movable platen 11 and the fixing
member 13. The respective gaps between two members of the movable
platen 11, the fixing member 13, the connecting member 14, the
movable upper mold 3, and the stationary lower mold 2 are sealed by
the sealing members 8, respectively.
[0036] Moreover, a plurality of ejector pins 16 (although a pair of
ejector pins are used in the embodiment shown in the drawings, they
may be three or more according to the number of cavities) are
inserted into the metal mold 1 so that they can thrust into the
cavities 5 of the metal mold. A connecting rod 17 of these ejector
pins 16 is inserted through the holes in the movable platen 11 and
the fixing member 13 and constituted so that the lower end face of
each ejector pin 16 may be in agreement with the top face of the
corresponding metal mold cavity 5 by means of an upwardly urging
means and a stopper means (not shown). Incidentally, if the movable
platen 11 is elevated to a top dead center after completion of the
injection-molding, the upper end face of the connecting rod 17
abuts on the lower end face of a cylinder rod 19 of an ejector
cylinder 18 which is attached to the stationary platen 10 so as to
align with the connecting rod 17. By actuating the ejector cylinder
18, the cylinder rod 19 depresses the connecting rod 17 and the
ejector pins 16 thrust into the cavities 5 respectively.
[0037] Further, a cylindrical vacuum housing 20 is fixedly secured
to the underside of the movable platen 11 through the medium of a
sealing member 8 so as to be suspended therefrom to surround the
movable upper mold 3. On the other hand, a sealing frame 21 is
fixedly secured to the upper surface of the main platen 7 at the
position corresponding to the cylindrical vacuum housing similarly
through the medium of a sealing member 8. When the clamping of the
movable upper mold 3 to the stationary lower mold 2 is performed by
moving the movable platen 11 downward, the outside surface of the
vacuum housing 20 may slide on the inner surface of the sealing
frame 21 through the medium of a sealing member 8 to form a sealed
injection-molding section space "X".
[0038] To a predetermined position of the main platen 7, a molded
article extraction cylinder 22 equipped with arm parts 23 which can
access to and retreat from the injection-molding section at a
predetermined height is attached.
[0039] On the other hand, a vacuum chamber 24 for hermetically
forming a heat-melting section space "Y" is arranged under the main
platen 7 and supported by a frame 48. The shut-off and
intercommunication between the injection-molding section space "X"
mentioned above and the heat-melting section space "Y" of the
vacuum chamber 24 are performed by the closing and opening of the
opening 6 by means of a shutter 26 which is actuated by a shutter
cylinder 25 so as to move forward and rearward while sliding on the
underside surface of the main platen 7.
[0040] In the vacuum chamber 24, a cylindrical injection sleeve 27
is disposed just under the position which is in alignment with the
sprue 4 of the stationary lower mold 2 and the opening 6 of the
main platen 7. The cylindrical injection sleeve 27 is provided with
an injection plunger 28 which is slidably disposed therein. The
injection plunger 28 is actuated by an injection cylinder 29 which
is attached to the lower part of the vacuum chamber 24. Further,
the lower end part of the injection sleeve 27 is fixedly secured to
a sleeve holding member 30. This sleeve holding member 30 is
actuated by a sleeve-moving cylinder 31 and vertically reciprocated
while being guided with a sleeve movement guide pin 32.
Accordingly, by actuating the sleeve-moving cylinder 31 to effect
vertical reciprocation of the sleeve-holding member 30, the
injection sleeve 27 is elevated toward the sprue 4 of the metal
mold 1 and lowered to the starting position.
[0041] Further, a high-frequency induction heating coil 34 as a
heating means is arranged around the upper part of the injection
sleeve 27. The heating means is not restricted to the
high-frequency induction heating and, of course, any known means
such as one resorting to the phenomenon of resistance heating may
be adopted.
[0042] Furthermore, in the vacuum chamber 24 a matrix alloy feeder
35 is disposed in alignment with a side opening 33 of the
above-mentioned injection sleeve 27. This matrix alloy feeder 35
comprises a matrix alloy feed tubular body 36 installed in the
height location connectable to the side opening 33 of the
above-mentioned injection sleeve 27, a matrix alloy cassette 37
disposed on this matrix alloy feed tubular body 36, a matrix alloy
supply plunger 38 slidably disposed in the matrix alloy feed
tubular body 36 mentioned above, and a matrix alloy feed cylinder
39 which actuates the matrix alloy supply plunger mentioned above.
The matrix alloy feed cylinder 39 and the matrix alloy supply
plunger 38 actuated by it function as the forcibly transferring
means to move the matrix alloy ingot "A" which has dropped into the
matrix alloy feed tubular body 36 from the matrix alloy cassette 37
into the injection sleeve 27.
[0043] The matrix alloy cassette 37 comprises a turntable 41
rotatably disposed on a mount 40 which is fixedly secured to the
matrix alloy feed tubular body 36 and a plurality (although four in
the case of the embodiment shown in the drawings, two or three or
five or more may be used) of vertical-type cylindrical matrix
alloy-accommodating magazines 42 disposed on this turntable 41, as
shown in FIGS. 1-4 and 5. In each of the vertical-type cylindrical
matrix alloy-accommodating magazines 42 a predetermined number of
matrix alloy ingots "A" formed into the predetermined dimensions
are accommodated in each matrix alloy-accommodating magazine 42. By
fitting a central bore 43 of the above-mentioned turntable 41 of
the matrix alloy cassette 37 on a rotating shaft of a stepping
motor 44, the turntable 41 can be rotated stepwise with a
predetermined time interval and each of the matrix
alloy-accommodating magazines 42 can be located one by one over the
matrix alloy feed tubular body 36 and also on an opening 45 of the
mount 40.
[0044] While the matrix alloy ingot "A" of the bottom which has
dropped into the matrix alloy feed tubular body 36 is supplied into
the injection sleeve 27 by means of the matrix alloy supply plunger
38, the matrix alloy ingots "A" accommodated in the matrix
alloy-accommodating magazine 42 in the piled state do not drop into
the matrix alloy feed tubular body 36 because the opening 45 of the
mount 40 is closed by the matrix alloy supply plunger 38. However,
when the matrix alloy supply plunger 38 retreats to open the
opening 45 of the mount 40, the next ingot of the bottom will drop
into the matrix alloy feed tubular body 36 and will be served for
the next supply. In this way, the matrix alloy ingots "A" in the
matrix alloy-accommodating magazine 42 will drop and supplied to
the injection sleeve 27 one by one with a predetermined time
interval. When the matrix alloy-accommodating magazine 42 becomes
empty, the turntable 41 will rotate only a predetermined angle and
the following matrix alloy-accommodating magazine 42 will be
arranged in the supply position.
[0045] The above-mentioned matrix alloy feeder 35 is attached to a
slide type lid 46 of the vacuum chamber 24. This lid 46 is slidably
laid on guide rails 47 so that the whole matrix alloy feeder 35 can
pull out by pulling the lid 46. Accordingly, after completion of
the injection molding using the matrix alloy ingots "A" in all the
matrix alloy-accommodating magazines 42, a large number of matrix
alloy ingots "A" can be ready for supply by one operation which
comprises opening a chamber air valve 53 connected to the vacuum
chamber 24 to cancel the vacuum condition (the evacuation system L2
of the vacuum chamber 24 is shut off at this time), pulling out the
lid 46, and exchanging the matrix alloy cassette 37 for a new one.
Incidentally, if the lid 46 is set to the vacuum chamber 24, the
leading end face of the matrix alloy feed tubular body 36 will abut
on the peripheral part of the side opening 33 of the injection
sleeve 27, and the sealing between the lid 46 and the vacuum
chamber 24 will be effected by a sealing member 8.
[0046] Alternatively, the matrix alloy feeder may be constructed
such that the matrix alloys accommodated in the matrix
alloy-accommodating magazine are moved upward by a vertically
reciprocating pin, for example, and the matrix alloy now in the top
position is transferred to the position just over the sleeve by a
transferring means such as an arm and charging the matrix alloy
into the sleeve from above.
[0047] One line L1 (metal mold evacuation line) of the vacuum
evacuation system L of a vacuum pump 50 (comprising a diffusion
pump and a rotary pump) is connected to the metal mold exhaust
holes 15 formed in the movable platen 11 and the fixing member 13
so that the evacuation is continued until the inside of the
injection-molding section space "X" reaches a predetermined degree
of vacuum. Other line L2 is connected to the vacuum chamber 24 so
that the evacuation is continued until the inside of the
heat-melting section space "Y" reaches a predetermined degree of
vacuum. A metal mold air valve 54 for canceling the vacuum
condition of the injection-molding section space "X" and also a
vacuum reserve tank 51 are connected to the metal mold exhaust line
L1 so that the injection-molding section space "X" can be changed
to a vacuum condition instantaneously after the clamping of the
movable upper mold 3 to the stationary lower mold 2.
[0048] Further, an inert gas container 52 is also connected to the
vacuum chamber 24 so that the heat melting of the matrix alloy can
be performed under an inert gas atmosphere, such as Ar, depending
on the kind of matrix alloy to be used. Reference numerals 55-59
are solenoid valves.
[0049] Next, the injection-molding process using the apparatus
mentioned above will be described.
<Matrix Alloy Supply Process>
[0050] First, After pulling out the lid 46 and setting the matrix
alloy cassette 37 in the matrix alloy feeder 35 as described above,
the lid 46 is shut. When the chamber air valve 53 is closed, the
solenoid valve 58 is opened to effect vacuum suction of the
heat-melting section space "Y" of the vacuum chamber 24. At this
time, the shielding shutter 26 is closed and the matrix alloy feed
section and the heat-melting section are incorporated in the one
vacuum chamber 24.
[0051] When one of the matrix alloy-accommodating magazines 42 of
the matrix alloy cassette 37 is set on a predetermined position,
the matrix alloy feed cylinder 39 is actuated so that the matrix
alloy ingot "A" which has dropped into the matrix alloy feed
tubular body 36 from the matrix alloy-accommodating magazine 42 is
pushed into the injection sleeve 27 by means of the matrix alloy
supply plunger 38, as shown in FIG. 1.
<Heat-Melting Process>
[0052] Next, the injection cylinder 29 is actuated so that the
injection plunger 28 pushes up the matrix alloy ingot "A" to a
melting zone, as shown in FIG. 2. Here, an electric current is
passed through the high-frequency induction heating coil 34 to
perform the heat-melting of the matrix alloy ingot "A". At this
time, the movable upper mold 3 is clamped to the stationary lower
mold 2 and the injection-molding section space "X" in the vacuum
housing 20 is evacuated to form the state ready for injection
molding.
<Injection-Molding Process>
[0053] After the molten metal in the injection sleeve 27 has
reached a predetermined temperature (the measurement of its
temperature may be performed by any suitable method such as, for
example, a method of disposing a thermocouple in the injection
plunger 28 or a method of using a radiation thermometer as in the
case of the example described hereinafter), the high-frequency
induction heating coil 34 is demagnetized and the shutter cylinder
25 is actuated to open the shielding shutter 26, thereby
intercommunicating the injection-molding section space "X" and the
heat-melting section space "Y". At this stage, the sleeve-moving
cylinder 31 and the injection cylinder 29 are promptly actuated
synchronously to effect elevation of the injection sleeve 27 and
the injection plunger 28, the upper end of the injection sleeve 27
closely contacts the peripheral part of the sprue 4 of the metal
mold 1, as shown in FIG. 3, and the molten metal pressurized by the
injection plunger 28 which still moves upward by a predetermined
distance is injected and filled into the metal mold cavities 5 and
molded therein by rapid solidification because its heat is taken by
the metal mold 1. At this time, since the metal mold 1 is evacuated
from the ejector section which is the terminal side of the flow of
the molten metal through the metal mold exhaust hole 15 of the
movable platen 11, the flow of the molten metal enters into the
metal mold cavities 5 with the exhaust air flow, the entrapment of
air bubbles in the molten metal can happen only with
difficulty.
<Molded Article Extraction Process>
[0054] After completion of the injection-molding, as shown in FIG.
4, the injection sleeve 27 and the injection plunger 28 retreat to
the original locations respectively, the shielding shutter 26 is
closed, the solenoid valve 55 is closed, the metal mold air valve
54 is opened, and thereafter the movable platen 11 is elevated by
means of the mold-clamping cylinders 12 to open the metal mold 1.
When the movable platen 11 reaches a top dead center, the upper end
face of the connecting rod 17 of the ejector pin 16 will abut on
the lower end face of the cylinder rod 19 of the ejector cylinder
18. At this stage, since the solidified and molded article "B" has
been separated from the stationary lower mold 2 along with the
movable upper mold 3, the ejector cylinder 18 is actuated to eject
the ejector pin 16 downward, thereby separating the molded article
"B" from the movable upper mold 3 and dropping it on the stationary
lower mold 2. Subsequently, by the actuation of the molded article
extraction cylinder 22, the arm parts 23 move forward, grasp the
molded article "B", and then retreat to the original position to
take out the molded article "B" from the apparatus. At this time,
the solenoid valves 56 and 57 are opened, the vacuum reserve tank
51 is connected with the vacuum pump 50, and the degree of vacuum
in the vacuum reserve tank 51 is increased during the period of the
mold opening process.
<Shot Cycle>
[0055] After extraction of the molded article, the mold-clamping
cylinders 12 are actuated again to close the metal mold 1.
Subsequently, the metal mold air valve 54 is closed and the
solenoid valve 55 is opened. After the injection-molding section
space "X" is connected with the vacuum reserve tank 51 and
preliminarily evacuated, the solenoid valve 56 is closed, and thus
the injection-molding section space is connected with a vacuum pump
50 (the solenoid valve 57 is usually in an opened state).
Therefore, the vacuum condition of the injection-molding section
space "X" is established for a very short period of time, and the
apparatus returns to the condition shown in FIG. 1 and proceeds to
the next injection cycle.
[0056] On the other hand, in the matrix alloy feeder 35, since the
next matrix alloy ingot "A" which has dropped into the matrix alloy
feed tubular body 36 from the matrix alloy-accommodating magazine
42 when the matrix alloy supply plunger 38 has been retreated is
pushed out of the tubular body by the matrix alloy supply plunger
38 and is supplied into the injection sleeve 27, it is subjected to
the following shot cycle.
[0057] In the manner as described above, the shot cycle is repeated
automatically and continuously until all the matrix alloy ingots
"A" accommodated in respective matrix alloy-accommodating magazines
42 of the matrix alloy cassette 37 are used up. After the matrix
alloy ingots "A" of the matrix alloy cassette 37 have been
completely used up, the solenoid valve 58 is closed and the chamber
air valve 53 is opened, and then the lid 46 is pulled out and the
matrix alloy cassette 37 is exchanged for a new one, as described
hereinbefore. After the exchange of cassette has been completed,
the lid 46 is shut and the shot cycle as described above is
repeated again.
EXAMPLE
[0058] Preforms (matrix alloys) were prepared by homogeneously
melting the metal glass raw materials (Zr, Al, Cu, etc.) by an arc
melting process so as to have the respective compositions shown in
the Table. In the preparation of these preforms, an inert gas
containing 3 vol. % of hydrogen gas was used to uniformly
incorporate hydrogen into the preforms. For the comparison, the
preforms containing no hydrogen were also prepared by using an
inert gas containing no hydrogen gas.
[0059] By using each preform obtained as described above, a test
piece of metal glass was prepared by casting it with the apparatus
as shown in FIG. 1 mentioned above (die-casting).
[0060] Each test piece of metal glass obtained as described above
was subjected to the fatigue test. The results are shown in the
Table and FIGS. 6-9. Incidentally, in FIGS. 6-9 the symbol "E" of
the abscissa axis represents an exponential function, for example,
1.0E+01 means 1.0.times.10 and 1.0E+02 means
1.0.times.10.sup.2.
[0061] The fatigue test was performed by using an Ono type rotating
bending fatigue tester using sign wave repeated stress under the
condition of the stress ratio R=-1. Cycle frequency was 13 Hz and
the fatigue test was performed in the air at room temperature. As a
test piece, a rod-like test piece (the sandglass type having a
diameter of 16 mm and a constricted central portion, shoulder
radius (curvature radius of a constriction transition part) R=16
mm, diameter of the portion to be held in the chuck part of the
tester (diameter of the constricted part) .phi.=8 mm, the shortest
diameter of the portion to be fractured, .phi.=4 mm, and gauge
length L=20 mm) was used. Accordingly, the result means a fatigue
test result of a smooth material (without notch). TABLE-US-00001
TABLE Fa- tigue Limit Num- ber of cy- Containing no hydrogen
Containing hydrogen cles Zr.sub.50Cu.sub.40Al.sub.10
Zr.sub.60Cu.sub.30Al.sub.10 Zr.sub.50Cu.sub.30Ni.sub.10Al.sub.10
Zr.sub.55Cu.sub.30Ni.sub.5Al.sub.10 Zr.sub.50Cu.sub.40Al.sub.10
Zr.sub.60Cu.sub.30Al.sub.10 Zr.sub.50Cu.sub.30Ni.sub.10Al.sub.10
Zr.sub.55Cu.sub.30Ni.sub.5Al.sub.10 2.5 .times. 1360 1250 1200 1000
1350 1210 1340 1260 10.sup.3 6.0 .times. 920 850 1000 900 900 800
1120 1040 10.sup.3 1.2 .times. 700 680 850 750 750 680 1050 900
10.sup.4 2.5 .times. 600 550 700 670 730 640 980 880 10.sup.4 1.3
.times. 360 320 580 500 710 610 960 810 10.sup.6 1.0 .times. 260
250 500 350 700 600 950 800 10.sup.7
[0062] As being clear from the results shown in the Table and FIGS.
6-9, the samples prepared from the hydrogen-containing metal glass
have exhibited considerably improved fatigue limit in relation to
the number of cycles as compared with the samples prepared from the
metal glass containing no hydrogen.
[0063] While certain specific embodiments and working examples have
been disclosed herein, the invention may be embodied in other
specific forms without departing from the spirit or essential
characteristics thereof. The described embodiments and examples are
therefore to be considered in all respects as illustrative and not
restrictive, the scope of the invention being indicated by the
appended claims rather than by the foregoing description and all
changes which come within the meaning and range of equivalency of
the claims are, therefore, intended to be embraced therein.
* * * * *