U.S. patent application number 10/600588 was filed with the patent office on 2004-01-08 for titanium copper alloy having excellent strength and bendability, and manufacturing method thereof.
This patent application is currently assigned to NIPPON MINING & METALS Co., Ltd.. Invention is credited to Hatano, Takaaki, Izumi, Chihiro.
Application Number | 20040003878 10/600588 |
Document ID | / |
Family ID | 29996641 |
Filed Date | 2004-01-08 |
United States Patent
Application |
20040003878 |
Kind Code |
A1 |
Izumi, Chihiro ; et
al. |
January 8, 2004 |
Titanium copper alloy having excellent strength and bendability,
and manufacturing method thereof
Abstract
A titanium copper alloy having excellent strength and
bendability comprising 1.0 to 4.5% by mass of Ti, the balance of
copper and inevitable impurities, characterized in that; diameters
of the intermetallic compound particles consisting of Cu and Ti
precipitated in the alloy are 3 .mu.m or less; the average number
of the intermetallic compound particles having the diameters of 0.2
to 3 .mu.m is 700 or less per a cross-sectional area of 1000
.mu.m.sup.2 in a transverse direction to a rolling direction; the
average grain size measured in the above cross-sectional area is 10
.mu.m or less; and a tensile strength is 890 MPa or more.
Inventors: |
Izumi, Chihiro;
(Kanagawa-ken, JP) ; Hatano, Takaaki;
(Kanagawa-ken, JP) |
Correspondence
Address: |
DRINKER BIDDLE & REATH
ONE LOGAN SQUARE
18TH AND CHERRY STREETS
PHILADELPHIA
PA
19103-6996
US
|
Assignee: |
NIPPON MINING & METALS Co.,
Ltd.
Tokyo
JP
|
Family ID: |
29996641 |
Appl. No.: |
10/600588 |
Filed: |
June 19, 2003 |
Current U.S.
Class: |
148/682 ;
148/411 |
Current CPC
Class: |
C22C 9/00 20130101; C22F
1/08 20130101 |
Class at
Publication: |
148/682 ;
148/411 |
International
Class: |
C22F 001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2002 |
JP |
2002-182145 |
Claims
What is claimed is:
1. A titanium copper alloy having excellent strength and
bendability characterized in that; it comprises 1.0 to 4.5% by mass
of Ti, the balance of copper and inevitable impurities; diameters
of intermetallic compound particles consisting of Cu and Ti
precipitated in the alloy are 3 .mu.m or less; the average number
of said intermetallic compound particles having the lo diameters of
0.2 to 3 .mu.m is 700 or less per a cross-sectional area of 1000
.mu.m.sup.2 in a transverse direction to a rolling direction; the
average grain size measured in a cross-sectional area in a
transverse direction to a rolling direction is 10 .mu.m or less;
and a tensile strength is 890 MPa or more.
2. The titanium copper alloy according to claim 1, wherein the
average number of the intermetallic compound particles having the
diameters of 0.2 to 3 .mu.m is 6 to 700 per a cross-sectional area
of 1000 .mu.m.sup.2 in a transverse direction to a rolling
direction.
3. A manufacturing method of the titanium copper alloy according to
claim 1 or 2 comprising a hot rolling, a cold rolling, a solution
treatment, a cold rolling and an aging treatment, of a titanium
copper alloy ingot in this order characterized in that; the ingot
is heated at a temperature of 850 to 950.degree. C. for 30 minutes
or more before the hot rolling and then the ingot is hot rolled and
the temperature in the end of the hot rolling is 700.degree. C. or
more; in the solution treatment, the material is annealed at a
temperature in a range between (T-50) .degree. C. and (T+10)
.degree. C., wherein T is a temperature at which the solubility of
Ti in Cu is equal to the concentration of Ti contained in the
alloy; and thereafter the annealed material is cooled at a cooling
rate of 100.degree. C./sec or more.
4. A manufacturing method of the titanium copper alloy according to
claim 3, wherein a reduction ratio in the cold rolling between the
solution treatment and the aging treatment is 50% or less.
5. A manufacturing method of the titanium copper alloy according to
claim 3 or 4, wherein the aging treatment is conducted at a
temperature of 300 to 600.degree. C.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention is related to a titanium copper alloy having
excellent strength and bendability and a manufacturing method
thereof.
[0003] 2. Description of the Related Art
[0004] Excellent strength and electrical conductivity are required
as fundamental properties for a copper alloy used for electrical
terminals and connectors. Also, in conjunction with recent
miniaturization of electronic products, miniaturization and
thinness of electronic components of the products are required.
Since metal materials used for such terminals or connectors are
subjected to severe and complicated bending treatment, metal
materials having excellent bendability are required. As for a high
strength copper alloy, use of an age hardening type copper alloy is
increasing recently. By applying an aging treatment to a
supersaturated solid solution, fine precipitates are homogeneously
dispersed in the alloy, resulting in a higher strength of the
alloy. Among these age hardening type copper alloys, copper alloys
containing Ti (hereinafter, referred to as "titanium copper
alloys") are widely used as various kinds of terminals and
connectors of electronic devices because of their excellent
strength and workability.
[0005] Same as a titanium copper alloy, a beryllium copper alloy
has been manufactured as a high strength copper alloy. However, a
beryllium copper alloy has such problems that beryllium compounds
have toxicity and manufacturing process thereof is complicated and
the production of a beryllium copper alloy entails high cost.
Therefore, a titanium copper alloy having excellent strength and
bendability is now in increasing demand. A titanium copper alloy
obtains a high strength by precipitation of intermetallic compound
particles of Cu-Ti system in a matrix in an aging treatment.
[0006] Although fine precipitates contribute to raise the strength
of a titanium copper alloy, coarse precipitates do not contribute
to raise the strength of the alloy. Rather, coarse precipitates in
the alloy may adversely affect the performances of the alloy when
the alloy is bent, coarse precipitates become starting points of
cracking resulting in deterioration of bendability of the alloy.
When the temperature at the solution treatment of an alloy before
the aging treatment is set to be high, coarse precipitates do not
appear. However, since the average grain size of the treated alloy
becomes large, the treated alloy would be insufficient relating to
the high strength of the quality that is recently demanded.
[0007] On the contrary, when the temperature at the solution
treatment is set to be low, although the grain becomes fine, coarse
precipitates remain in the matrix and it may cause detrimental
effects such as, when the alloy is bent, the coarse precipitates
become starting points of cracking resulting in deteriorated
bendability of the alloy.
[0008] Further, with respect to the generation of coarse
precipitates, there is a possibility of the coarse precipitates
remaining not only in the conditions of the solution treatment
before the aging treatment, but also in the conditions of the hot
rolling. The invention is intended to solve the above-mentioned
problems and to provide a titanium copper alloy having excellent
strength and bendability.
[0009] The present inventors have found out that; in manufacturing
of a titanium copper alloy, by properly adjusting the heat
treatment conditions before the hot rolling, in the end of the hot
rolling and in the solution treatment in order to control
precipitation of coarse precipitates which do not contribute to the
strength of the alloy, the titanium copper alloy can be improved in
strength and bendability.
SUMMARY OF THE INVENTION
[0010] The present invention provides (1) to (3) as follows.
[0011] (1) A titanium copper alloy having excellent strength and
bendability characterized in that; it comprises 1.0 to 4.5% by mass
of Ti, the balance of copper and inevitable impurities; diameters
of intermetallic compound particles consisting of Cu and Ti
precipitated in the alloy are 3 .mu.m or less; the average number
of the intermetallic compound particles having the diameters of 0.2
to 3 .mu.m is 700 or less, preferably 6 to 700 per a
cross-sectional area of 1000 .mu.m.sup.2 in a transverse direction
to a rolling direction; the average grain size measured in a
cross-sectional area in a transverse direction to a rolling
direction is 10 .mu.m or less; and a tensile strength is 890 MPa or
more.
[0012] (2) A manufacturing method of the titanium copper alloy
according to the above (1) comprising a hot rolling, a (first) cold
rolling, a solution treatment, a (second) cold rolling and an aging
treatment, of a titanium copper alloy ingot in this order
characterized in that; the ingot is heated at a temperature of 850
to 950.degree. C. for 30 minutes or more before the hot rolling and
then the ingot is hot rolled and the temperature in the end of the
hot rolling is 700.degree. C. or more; in the solution treatment,
the material is annealed at a temperature in a range between (T-50)
.degree. C. and (T+10) .degree. C., wherein T is a temperature at
which the solubility of Ti in Cu is equal to the concentration of
Ti contained in the alloy; and thereafter the annealed material is
cooled at a cooling rate of 100.degree. C./sec or more.
[0013] (3) A manufacturing method of the titanium copper alloy
according to the above (2), wherein a reduction ratio in the second
cold rolling is 50% or less.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 shows a phase diagram of Cu-Ti system (Experimental
data on the Ti-Cu stable equilibrium (Cu) solvus, coherent solvus,
and spinodal).
[0015] The above-mentioned Cu-Ti phase diagram in FIG. 1 is quoted
from "Phase Diagrams of Binary Copper Alloys" by P. R. Subramanian,
D. J. Chakrabarti and D. E. Laughlin, ASM International, pp447-460
(1994).
[0016] The temperature T .degree. C. at which the solubility of Ti
in Cu is equal to the concentration of Ti contained in the alloy is
a temperature on a solvus (solid solubility) shown in FIG. 1.
Illustratively, when the concentration of Ti is 2.6% by mass, T
.degree. C. is 755.degree. C.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Hereinbelow, the present invention is described in
detail.
[0018] (i) The Concentration of Ti
[0019] Ti is characterized in that it induces spinodal
decomposition in the aging treatment of a titanium copper alloy,
thereby generating a modulated structure in the alloy, and ensuring
very high strength of the alloy. However, if the concentration of
titanium is less than 1.0% by mass, reinforcement of the alloy
caused by the aging treatment cannot be expected. Conversely, if
the concentration of titanium exceeds 4.5% by mass, precipitation
is likely to occur in a grain boundary in the aging treatment, thus
the strength of the alloy may be lowered and cracking may occur in
the grain boundary when the alloy is bent. From the above, the
concentration of titanium in the alloy should be 1.0 to 4.5% by
mass. Further, in addition to the alloy, such as chromium,
zirconium, nickel and iron may be added in a total amount of 1.0%
by mass or less so as to have the same effect as that of
titanium.
[0020] (ii) Intermetallic Compound Particles of Cu and Ti
Precipitated in the Matrix
[0021] In a titanium copper alloy, high strength can be achieved by
precipitation of the intermetallic compound particles of Cu and Ti
in the matrix. However, the intermetallic compound particles of Cu
and Ti contributing to excellent strength of the alloy are fine
particles having the diameters of less than 0.2 .mu.m. The
intermetallic compound particles having the diameters of 0.2 .mu.m
or more do not contribute to excellent strength but become starting
points of cracking when the alloy is bent. Especially, the
intermetallic compound particles having the diameters of more than
3 .mu.m cause extraordinary impaired bendability. Thus, it is
necessary that the diameter of the intermetallic compound particles
is set to be 3 .mu.m or less. Further, the inventors have found
that even the intermetallic compound particles having the diameters
of 0.2 to 3 .mu.m adversely affect bendability of the alloy when
the number of particles is more than 700 per a cross-sectional area
of 1000 .mu.m.sup.2 in a transverse direction to a rolling
direction. Accordingly, the diameter of the intermetallic compound
particles of Cu and Ti precipitated in the matrix should be 3 .mu.m
or less, and the average number of the intermetallic compound
particles having the diameters of 0.2 to 3 .mu.m should be 700 or
less per a cross-sectional area of 1000 .mu.m.sup.2 in a transverse
direction to a rolling direction. Here, the composition of an
intermetallic compound of Cu and Ti is Cu.sub.3-4Ti.
[0022] On the other hand, in punch press-work, since the
intermetallic compound particles of Cu and Ti having the diameters
of 0.2 to 3 .mu.m promote transmission of cracking in the alloy
which eventually prevent a press mold wearing. Therefore, the
presence of the intermetallic compound particles having the
diameters of 0.2 to 3 .mu.m in the average number of 6 or more per
a cross-sectional area of 1000 .mu.m.sup.2 in a transverse
direction to a rolling direction imparts long-life to the press
mold to be used. From the above, the average number of the
intermetallic compound particles having the diameters of 0.2 to 3
.mu.m is preferably 6 to 700 per a cross-sectional area of 1000
.mu.m.sup.2 in a transverse direction to a rolling direction.
[0023] (iii) Average Grain Size
[0024] The grain size of a titanium copper alloy affects strength
and bendability of the alloy largely. The grain having a size of
more than 10 .mu.m disables to obtain the desired strength.
Adversely, when the alloy having an average grain size of more than
10 .mu.m is bent in the process, roughness is likely to occur on
the alloy surface. Thus, the average grain size should be 10 .mu.m
or less. Here, measurement of the average grain size is carried out
by exposing a structure of a cross-sectional area of a specimen
alloy in a transverse direction to a rolling direction by means of
etching (water (100 mL)-FeCl.sub.3 (5 g)-HCl (10 mL)) and by
obtaining an average grain size by means of an intercept method
according to JIS H 0501.
[0025] (iv) Manufacturing Method
[0026] In the manufacturing method of a titanium copper alloy of
the invention, a hot rolling, a first cold rolling, a solution
treatment, a second cold rolling and an aging treatment, of a
titanium copper alloy ingot are conducted in this order. Further,
after the first cold rolling, annealing may be carried out for the
purpose of recrystalization, and then a further cold rolling and a
solution treatment can be conducted in this order. The
manufacturing method of the invention is described in detail
below.
[0027] (a) Hot Rolling
[0028] In general, manufacturing of a titanium copper alloy ingot
is carried out by semi-continuous casting process. In
solidification step at the casting, coarse intermetallic compound
particles of Cu-Ti system may occur in the matrix. The occurred
coarse intermetallic compound particles would be solved in the
matrix so as to form a solid solution by heating at a temperature
of 850.degree. C. or more for 30 minutes or more and the subsequent
hot rolling wherein the temperature in the end of the hot rolling
should be 700.degree. C. or more. However, when the temperature
before the hot rolling exceeds 950.degree. C., stubborn scale
occurs on the material surface, becoming the reason of cracking in
rolling and bad yields owing to removal of the scale. Accordingly,
the temperature before the hot rolling should be between
850.degree. C. and 950.degree. C.
[0029] (b) Solution Treatment
[0030] In order to obtain homogeneously dispersed fine
intermetallic compound particles of Cu and Ti, the solution
treatment is commonly conducted at a temperature on or above the
solvus shown in FIG. 1; specifically, at or above the temperature
at which the solubility of Ti in Cu is equal to the concentration
of Ti contained in the alloy. However, high annealing temperature
promotes the grain growth resulting in insufficient strength and/or
bendability. In the invention, so as to obtain an average grain
size of 10 .mu.m or less, it is necessary to anneal at a
temperature of (T+10).degree. C. or less, wherein T is a
temperature at which the solubility of Ti in Cu is equal to the
concentration of Ti contained in the alloy. Further, when the
temperature in the solution treatment is less than (T-50).degree.
C., Ti would not form solid solution with Cu resulting in the
number of the intermetallic compound particles of Cu and Ti being
out of the range of the invention. Accordingly, the solution
treatment should be carried out at a temperature in the range
between (T-50).degree. C. and (T+10).degree. C. Further, when a
cooling rate of the annealed alloy is not more than 100.degree.
C./s, precipitation of the intermetallic compound particles would
occur in the grain boundary in the alloy. The precipitation of the
intermetallic compound particles may cause cracking in the grain
boundary when the alloy is subjected to a bending stress, and
accordingly the cooling rate in the solution treatment should be
100.degree. C./s or more. The cooling method is not particularly
limited in the invention.
[0031] (c) Second Cold Rolling
[0032] In order to obtain the high strength alloy, a reduction
ratio in the second cold rolling after the solution treatment is
preferably high. However, since when a reduction ratio is more than
50%, work hardening of the alloy is excessive, texture of the alloy
caused by the rolling is developed too much, thus bendability in a
transverse direction to a rolling direction deteriorates
remarkably. For this reason, a reduction ratio is preferably 50% or
less in the second cold rolling. Further, when the Ti content is
about 3% by mass, the titanium copper alloy having excellent
strength, such as 890 MPa or more of a tensile strength, can be
obtained at a reduction ratio of about 10% or more.
[0033] Here, assuming that the thickness of the alloy plate before
the cold rolling is t.sub.0 and the thickness of the alloy sheet
after the cold rolling is t, the reduction ratio X of the cold
rolling is defined as:
X=(t.sub.0-t)/t.sub.0X100(%).
[0034] (d) Aging Treatment
[0035] The aging treatment of the titanium copper alloy is suitably
conducted at a temperature of 300 to 600.degree. C. in the
invention in order to obtain the desired strength and electrical
conductivity.
EXAMPLES
[0036] Firstly, using electrolytic copper or oxygen-free copper as
a raw material, copper alloy ingots (20 mm thick.times.100 mm
wide.times.200 mm long) of the various compositions shown in Table
1 were obtained by melting and casting in a high frequency vacuum
melting furnace. Subsequently, each ingot was heated and hot rolled
at a temperature described in Table 1 to obtain a plate having a
thickness of 8 mm. The scale on the surface of the plate was
removed and polished, then the first cold rolling was carried out
to obtain a sheet having a thickness of 0.43 mm. In the subsequent
solution treatment, each sheet was annealed for 30 minutes at a
temperature and cooled to the room temperature at a cooling rate
described in Table 1.
[0037] Then the second cold rolling was carried out at a reduction
ratio of 30% to obtain each sheet having a thickness of 0.3 mm,
followed by the aging treatment under conditions at which it is
able to obtain the highest strength for each specimen alloys. In
example 9, the reduction ratio in the second cold rolling was set
to be 60% in order to observe the effect of a reduction ratio on
bendability of the alloy.
[0038] For each alloy obtained from the above, various properties
were measured. Tensile strength was evaluated using a tensile
tester according to JIS Z 2241. Bending test of specimens was
conducted according to W bending test (JIS H 3130) under a
condition that bending radius/thickness of a sheet is 2. The convex
part on the surface of the specimen made by bending was observed by
an optical microscope. The evaluation standard of bendability of
the alloy was classified in three ranks: rank .largecircle.; no
wrinkle was observed, rank .DELTA.; large wrinkles was observed,
rank X; a cracking occurred.
[0039] In measurement of the average grain size, a structure of a
cross-sectional area of a specimen alloy in a transverse direction
to the rolling direction was exposed by means of etching (water
(100 mL)-FeCl.sub.3(5 g)-HCl(10 mL)) and an average grain size was
measured by means of the intercept method according to JIS H 0501.
In the intercept method, an average grain size in a direction of
sheet-thickness and an average grain size of sheet-width were
obtained by measuring the exposed structure. Then the average value
of these two average grain sizes was calculated and referred to as
"the average grain size" of the alloy. As for the observation of
the intermetallic compound particles of Cu and Ti precipitated in
the alloy, a cross-sectional area of the alloy in a transverse
direction to the rolling direction was polished by use of a
water-proof sand paper of #150, followed by further polishing so as
to obtain mirror finished surface by use of a finishing abrasive in
which colloidal silica having a particle diameter of 40 nm is
suspended. Then carbon vapor deposition was carried out on the
polished alloy specimen and a reflected electron image obtained by
use of FE-SEM (scanning electron microscope) (XL30SFEG,
manufactured by FEI Company Japan) was observed. The scanning field
was 1000 .mu.m.sup.2 and 5 fields each having different visions
were observed for each alloy. As for the evaluation of diameters of
the intermetallic compound particles in table 1, the minimum
diameter of a circle containing each intermetallic compound
particle of Cu and Ti in the observation field was actually
measured and a specimen containing intermetallic compound particles
having the diameters of more than 3 .mu.m was evaluated as "X". On
the other hand, a specimen containing no intermetallic compound
particle having a diameter of more than 3 .mu.m was evaluated as
".largecircle.". The number of the intermetallic compound particles
was obtained as the averaged number of the intermetallic compound
particles of Cu and Ti observed in 5 fields.
1TABLE 1 1 2 3 4 5 6 7 8 9 Example No. Concentration of Ti (mass %)
1.1 2.8 4.1 3.8 1.8 4.5 3.4 2.6 2.6 Temperature before the hot
rolling (.degree. C.) 860 875 850 900 855 870 880 860 860
Temperature in the end of the hot rolling (.degree. C.) 750 740 700
770 710 740 730 725 725 Temperature (T) of a solvus in a phase
diagram (.degree. C.) 640 767 834 820 701 852 800 755 755 Annealing
Temp. in the solution treatment (.degree. C.) 650 750 835 817 700
820 805 750 750 Cooling rate in the solution treatment (.degree.
C./s) 120 200 120 100 115 150 105 180 180 Reduction ratio in the
second cold rolling (%) 30 30 30 30 30 30 30 30 60 Tensile strength
(MPa) 915 989 1054 1034 936 1096 1004 954 1001 Bendability O O O O
O O O O .DELTA. Average grain size (.mu.m) 4 2 8 5 4 3 6 5 4
Diameter of precipitates (.ltoreq..mu.m) O O O O O O O O O Number
of precipitates (.ltoreq.700) 7 362 264 378 49 546 330 309 314
Comparative Example No. Concentration of Ti (mass %) 0.8 0.5 5.0
4.8 2.8 3.1 3.4 2.6 2.6 Temperature before the hot rolling
(.degree. C.) 850 880 870 890 830 850 875 860 860 Temperature in
the end of the hot rolling (.degree. C.) 710 730 730 750 710 675
730 725 725 Temperature (T) of a solvus in a phase diagram
(.degree. C.) 606 560 874 866 767 784 800 755 755 Annealing Temp.
in the solution treatment (.degree. C.) 610 565 850 840 760 790 810
700 800 Cooling rate in the solution treatment (.degree. C./s) 110
130 100 170 150 120 80 180 180 Reduction ratio in the second cold
rolling (%) 30 30 30 30 30 30 30 30 30 Tensile strength (MPa) 830
815 879 868 913 940 926 932 870 Bendability O O X X X X X X O
Average grain size (.mu.m) 5 5 3 3 4 6 4 1 35 Diameter of
precipitates (.ltoreq.3.mu.m) O O O O X X X X O Number of
precipitates (.ltoreq.700) 5 5 1583 894 659 1177 1428 1219 43
[0040] As can be seen from Table 1, the Example specimens of the
invention had excellent strength and bendability. Besides, in
Example No. 9, the composition of the alloy, the temperature before
the hot rolling, the temperature in the end of the hot rolling, the
annealing temperature in the solution treatment, and the cooling
rate after the solution treatment were the same as in Example No. 8
and the reduction ratio was out of the range specified in the above
mode (3) of the invention. The specimen of Example No. 9 was even
though excellent in tensile strength but inferior in bendability to
some extent to that of Example No. 8.
[0041] On the contrary, in Comparative Examples 1 and 2, since the
concentrations of Ti were less than the lower limit of the above
mode (1), the strength of these specimens was insufficient.
Further, in Comparative Examples 3 and 4, since the concentration
of Ti exceeded the upper limit of the above mode (1), precipitation
of the intermetallic compound particles of Cu and Ti occurred in
the grain boundary causing poor strength of the alloys. Also, in
Comparative Examples 3 and 4, although the coarse intermetallic
compound particles having the diameters of 3 .mu.m or more were not
present, the number of the intermetallic compound particles having
the diameters of 0.2 to 3 .mu.m exceeded the upper limit of the
above mode (1) resulting in poor bendability.
[0042] Since, in Comparative Example 5 the temperature before the
hot rolling was less than the lower limit of the above mode (2), in
Comparative Example 6 the temperature in the end of the hot rolling
was less than the lower limit of the above mode (2), and in
Comparative Example 7 the cooling rate after the solution treatment
was less than the lower limit of the above mode (2), the coarse
intermetallic compound particles having the diameters of 3 .mu.m or
more were present in the specimens of these Comparative Examples.
Further, in Comparative Examples 6 and 7, since the number of the
intermetallic compound particles having the diameters of 0.2 to 3
.mu.m was 700 or more, bendability was poor in these Comparative
Examples.
[0043] Furthermore, in Comparative Examples 8 and 9, the
composition of the alloy, the temperature before the hot rolling,
the temperature in the end of the hot rolling, the cooling rate
after the solution treatment, and a reduction ratio in the second
cold rolling were the same as in Example No. 8 and the annealing
temperature in the solution treatment was out of the range
specified in the above mode (2). In Comparative Example 8, since
the temperature in the solution treatment was low and Ti was not
solved completely into Cu in the solution treatment, the coarse
intermetallic compound particles having the diameters of 3 .mu.m or
more was present and the number of the intermetallic compound
particles having the diameters of 0.2 to 3 .mu.m was 700 or more
resulting in poor bendability. Further, in Comparative Example 8,
when the tensile test was conducted, the intermetallic compound
particles became starting points of fracture, thus the tensile
strength was inferior to that of Example 8. In Comparative Example
9, since the temperature in the solution treatment was high, the
grain grew large and the tensile strength was inferior to that of
Example 8.
[0044] As can be seen from the above description, in the invention,
by adjusting heat processing conditions before the hot rolling, in
the end of the hot rolling and in the solution treatment of
titanium copper alloy manufacturing method, and control this
precipitation of coarse precipitates which do not contribute to the
strength, the strength and bendability of a titanium copper alloy
are improved and it is possible to provide a copper alloy excellent
in strength and bendability which can be consistent with
miniaturization of electronic components.
* * * * *