JPH0645836B2 - TiPd type shape memory alloy - Google Patents

Description

TECHNICAL FIELD The present invention relates to a TiPd-based shape memory alloy having a high temperature operation function, which is an inexpensive shape memory alloy in which a part of Pd is replaced by Ta and W having a large atomic weight. Is.

[Prior Art] It is well known that TiNi alloys in the vicinity of an equiatomic ratio show a remarkable shape memory effect accompanying the reverse transformation of the thermoelastic martensitic transformation. Recently, the fields of application have expanded to include actuators, temperature sensors, arch wires,
It has been put to practical use in various fields such as brassieres.

Alloys showing shape memory effect are TiNi alloy, TiNiX
Alloys (X = CU, Cr, Fe, Al, V, Co ...) and CU-based alloys such as Cu—Zn—Al, Au—Cd alloys,
It reaches dozens of types such as Ag-Cd alloys. Among them, TiNi alloy and some TiN are offered as practical alloys.
iX alloy only. However, the maximum shape recovery temperature of these alloys is 100 ° C even in applications that do not consider repetition, and 70 ° C for reversible use that requires repetition.
Is the limit.

Using Ti—Pd alloy as an element has been studied as a means for increasing the shape recovery temperature. A part of Pd of TiPd alloy and TiPd alloy is Fe, Cu, C
It has been filed by the Netherlands that the TiPdX alloy substituted with o and Ni operates at a temperature of about 500 ° C.
-1502. In addition, recent studies have revealed the relationship between the amount of Pd and the shape recovery temperature, which are important for shape memory elements, and the mechanical properties.
(ISIJ international vol29. (1989) No.5).

[Problems to be Solved by the Invention] However, T which is regarded as a promising high temperature actuating element
Since the iPd alloy is almost equiatomic, the weight percentage of Pd is about 70%, and the large amount of Pd used as a noble metal causes a very high raw material cost of the device, which is a practical obstacle.

Moreover, in order to obtain an operating element at around 200 ° C., V, C
Even if Pd is replaced with r, Fe, Co, or Cu, the amount thereof is limited to 25% at most, and the raw material cost is still a problem.

Therefore, in view of the above-mentioned drawbacks, the technical problem of the present invention is TiP.
It is an object of the present invention to provide a novel shape memory alloy that can substantially maintain the high temperature operation function of a d-based alloy and can be at a practical cost.

[Means for Solving the Problems] According to the present invention, P of 45.0 to 51.0 [at%] is used.
For a TiPd alloy consisting of d and the balance Ti, a part of Pd is at least one of W and Ta and is 1.0 to 2
A TiPd-based shape memory alloy with 5.0 [at%] substitution is obtained.

Further, according to the present invention, Pd in the TiPd alloy consisting of 45.0 to 51.0 [at%] and the balance Ti is Pd.
Part of X element (where X is 0.01 to 10 [at%])
V, 0.01-10 [at%] Cr, 0.01-1
2 [at%] Mn, 0.01 to 3.7 [at%] N
i, 0.01 to 16 [at%] Fe, 0.01 to 20
[At%] of Co, 0.01 to 25.5 [at%] of C
TiPd substituted with at least one of u}
TiPd obtained by substituting the balance of Pd with at least one of W and Ta for the alloy X by 1.0 to 25.0 [at%].
A system shape memory alloy is obtained.

[Examples] Examples of the present invention will be described below. First, an outline of a TiPd-based shape memory alloy according to an embodiment of the present invention will be briefly described.

This TiPd-based shape memory alloy is 45.0-51.0.
[At% (atomic%)] Pd and the balance T consisting of Ti
It is obtained by substituting 1.0 to 25.0 [at%] of at least one of W and Ta for Pd with respect to the iPd alloy.

Therefore, the manufacturing process of this TiPd-based shape memory alloy will be described below.

The alloys shown in Table-1 were melted in an argon arc furnace and
Hot working was performed at a temperature of 1000 ° C to obtain strip-shaped samples with a thickness of approximately 1.0 mm.

Each of these samples was subjected to solution treatment at 1000 ° C for 1.0 hr, and then the transformation temperature was measured and shape memory was checked.

The transformation temperature is determined by measuring the electrical resistance by the four-terminal method, and the shape memory check is performed by transforming each test piece into a U shape at room temperature (20 ° C) and measuring the electrical resistance. This was done by observing the shape recoverability when heated to the above temperature.

Martensite transformation start temperature (Ms temperature) and Ti ₅₀ Pd _50-x
The relationship between W and the amount of Ta added represented _by the formula of X _x is shown in FIG. 1, and the Ms temperature decreases almost linearly with the amount of the third element added. However, the tendency is smaller than that of Fe, Cr, etc. It has been known from previous studies that the alloy containing 10 at% of Fe has an Ms temperature of about 150 ° C. and the alloy containing 10 at% of Cr has an Ms temperature of about 0 ° C. However, alloys containing W and Ta according to the present invention are known. Then, the Ms temperature is 10 each
It shows about 475 ° C. and 460 ° C. with addition of at%. Also,
In terms of atomic weight, W and Ta are about three times larger than those in the vicinity of 3d transition metal, and the effect of reducing the weight of Pd added, which is one of the objects of the present invention, is 3 times that in the vicinity of 3d transition metal.
It can be said that it is twice as large.

The results of examining the shape memory characteristics are shown in Table 1. The alloys according to the claims of the present invention showed almost perfect shape memory characteristics. Table 1 also shows the results of an examination of the hot workability at 1000 ° C. for the production of the test piece. However, it becomes difficult if the added amounts of W and Ta exceed 25%. Moreover, Pd also tends to become difficult as the equiatomic ratio of Ti ₅₀ Pd ₅₀ is increased.

According to the above, the reason why the present invention sets the Pd amount of the basic TiPd alloy substituted with the third element to be 45.0 to 51 at% is
If it is less than 5 at%, there is an effect of reducing the amount of Pd, but there is a problem in workability and shape memory. If it exceeds 51 at%,
This is because the workability is deteriorated, so no difference effect is observed. Also, the substitution amount of W and Ta is 1.0 to 2
The reason why 5 at% is set is that the substitution effect is not recognized when the content is less than 1 at%. On the other hand, when it exceeds 25 at%, the effect of substitution is noticeable, but the workability and memory tend to deteriorate.

In the above-described embodiment, it was explained that the effect of reducing the amount of Pd used could be obtained by replacing W and Ta, and the maximum amount of replacement could be set to 25.0 at% to maintain workability and memorability. It is also possible to previously substitute the X element near the 3d transition element (provided that X is at least one of V, Cr, Mn, Ni, Fe, Co, and Cu) as a transformation temperature point control factor. .

Therefore, the outline of the TiPd-based shape memory alloy according to another embodiment will be briefly described below.

This TiPd-based shape memory alloy is 45.0-51.0.
[At%] Pd, and a part of Pd in the TiPd alloy composed of the balance Ti described above is the X element {however, X is 0.
V of 01 to 10 [at%], 0.01 to 10 [at%]
Cr, 0.01-12 [at%] Mn, 0.01-
3.7 [at%] Ni, 0.01 to 16 [at%] Fe, 0.01 to 20 [at%] Co, 0.01 to 2
5.5 [at%] of at least one of Cu} for the TiPdX alloy substituted with at least one of W and Ta for the remainder of Pd 1.0 to 25.0
[At%] is obtained by substitution.

Figure 2 shows Ti ₅₀ Pd related to this TiPd type shape memory alloy.
_It shows the relationship between the added amount x [at%] of the X element in the _50-x X _x alloy and the shape recovery temperature [° C].

From FIG. 2, V, Cr, Mn, N used as the X element
The substitution amounts of i, Fe, Co, and Cu are 0.01 to 10 [at%] for V and 0.01 for Cr, respectively.
-10 [at%], and Mn 0.01 / 12 [a]
t%], 0.01 to 3.7 [at%] for Ni,
0.1 to 16 [at%] for Fe, 0.01 to 20 [at%] for Co, and 0.01 for Cu.
It can be seen that a TiPdX alloy suitable as a TiPd-based shape memory alloy material can be obtained within a range of ˜25.5 [at%].

FIG. 3 shows that the TiPd-based shape memory alloy was added with W and Ta [at%] and the martensite reverse transformation end temperature Af.
It is shown in relation to [° C].

From FIG. 3, it can be seen that the transformation temperature point can be remarkably controlled by adding X element. For example, if the X element is Ni
In this case, the transformation temperature point can be lowered by about 16 ° C. per 1 [at%], and by Cr, the transformation temperature point can be lowered by about 30 [° C.] per 1 [at%].

Incidentally, it has been found that even if W and Ta are added to the TiPdX alloy, the shape memory characteristics are maintained similarly to the TiPd-based shape memory alloys of the previous examples.

[Effects of the Invention] As described above, according to the present invention, the Pd content is reduced without impairing the characteristics of the TiPd alloy as a high-temperature actuating element, which is an essential feature of the TiPd alloy. Since the temperature point is controlled, the element with the required transformation point can be obtained.

[Brief description of drawings]

FIG. 1 shows a TiPd-based shape memory alloy according to one embodiment of the present invention in terms of the relationship between W and Ta addition amounts and martensite temperature. FIG. 2 shows another embodiment of the present invention. Related T
FIG. 3 shows the relationship between the amount of the X element added and the shape recovery temperature in the TiPdX alloy used for the iPd-based shape memory alloy. FIG. 3 shows the TiPd-based shape memory alloy according to another embodiment of the present invention. , Ta, and the martensitic reverse transformation temperature.

Claims (2)

[Claims] 1. A TiPd alloy consisting of 45.0 to 51.0 [at%] of Pd and the balance of Ti is 1.0 to 25.0 with a part of Pd being at least one of W and Ta.
[At%] TiPd obtained by substitution
System shape memory alloy. 2. A portion of Pd in a TiPd alloy consisting of 45.0 to 51.0 [at%] of Pd and the balance Ti is an X element (where X is 0.01 to 10 [at%] of Vd. ，
0.01-10 [at%] Cr, 0.01-12 [a
t%] of Mn, 0.01 to 3.7 [at%] of Ni,
0.01 to 16 [at%] Fe, 0.01 to 20 [a
t%] of Co and 0.01 to 25.5 [at%] of at least one of Cu, and the TiPdX alloy is replaced by at least one of W and Ta. A TiPd-based shape memory alloy obtained by substituting 0 to 25.0 [at%].