JPS6059035A - Shape memory cu-zn-al alloy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of Cu''Zn-Al based shape memory alloys, and in particular improves cold workability and strength without impairing shape memory properties. Shape memory alloys in general has the property of being formed into a predetermined shape in a region above the martensitic transformation temperature, deformed in a region below the martensitic transformation temperature, and then recovering to the predetermined shape when heated above the martensitic transformation temperature. It has the property of exhibiting superelasticity near the site transformation temperature, and various alloys have been developed and used for various purposes by utilizing the shape memory effect and superelasticity. Since the 2n-A/type shape memory alloy is advantageous in price, its application to various uses has been studied and, depending on the use, it has been put into practical use.

Conventionally, after hot working, Cu-Zn-A7-based shape memory alloys are heat-treated in a high temperature range (β phase) and then cold-worked, but the crystal grains tend to coarsen during the heat treatment, and in some cases The crystal grains were coarsened to 1 to 3111+N, which had the disadvantage of significantly impairing cold workability. In addition, coarsening of crystal grains shortens the number of repeated uses (life) when using the bidirectional shape memory effect, and when using superelasticity, it also causes non-selectivity in the direction of applied stress because the elastic anisotropy is originally large. There was a flaw that led to it.

In view of this, the present invention was developed based on the results of various studies on Cu-Zn-Aj?
Ni is added to the shape memory alloy composition, and Si,
By adding a predetermined amount of one type of P, the crystal grains are refined through the precipitation of Nl5l-based and NiP-based intermetallic compounds, and an alloy that can be easily cold-worked has been developed. The shape memory alloy of the present invention has A10.05
~io, owt (hereinafter wt% will simply be abbreviated as staff) and Zn9. Contains O~40.0%, N10.30~2.0%, and at least one of S Emperor and P 0.01~0.50
% and the remainder is Cu.

However, in the alloy of the present invention, A70.05 to 10.0, Zn 9.0 to 40.0%, and Ni 0.30 to 2.0%.
%, Si.

The reason for limiting the amount of P to 0.01 to 0.50% is that if the content is less than 0.05% AIo and 9.0% Zn, the required transformation temperature is too low and the shape memory effect cannot be obtained. Also, if the additive element N1 is less than 0.30%, if the amount of sl or p is less than 0.01% (each type is less than 0.01%), the required fine structure cannot be obtained, and if Al is
If the Zn content exceeds 0.0% or 40.0%, not only will cold working deteriorate due to the precipitation of the r phase, but also the shape memory effect may not be obtained, which is not realistic. In addition, Ni exceeds 2.0, and at least one of Si and P is 0.
．． This is because if it exceeds 50%, a fine structure can be obtained, but there is a drawback that the shape memory effect is impaired.

Examples of the alloy of the present invention will be described below.

Melt Cu using a graphite crucible, cover the hot water surface with charcoal powder, and then melt at least one of Si and P.
Type and Zn, A6. Ni was added and this was cast to form an inch bar with a length of 180 mm and a width of 1 mm with the composition shown in Table 1.
Ingots with a length of 2001 m and a thickness of 25 mm were obtained in 50 areas.

Next, the surface of each of these ingots is 2.5
After milling the surface by millimeter, it was hot-rolled into a bar with a diameter of 8 mm and a width of 15 mm.
A plate with a thickness of 8 mm was used. Table 1 shows the results of investigating these rods and plates for (1) cold workability, (2) tensile strength, and (2) shape memory.

For comparison, Table 1 lists all of the additive elements Ni, Si, and P for grain refinement (Cu-Z to be added).
The n-Aβ shape memory alloy is also described.

Cold workability is determined by heating and annealing the above bars and plates to a temperature of 600 to 700°C, and then cold working them to a processing rate of 80%, with no sassafure or cracks observed on the surface. When the processing rate is 70%, there are no cracks or cracks on the surface, but when the processing rate is 80%, there are cracks or cracks on the surface. is represented by an X mark.

The measurement of tensile strength was carried out using J-Ko S-$2241, with the processing rate of all samples set at 60%.

The shape memory effect was measured using a coil diameter of 10 mrn and a coil length of 5.
The coil length is extended to 100mm at a temperature 30°C lower than the Mf point (martensitic transformation end temperature), and then at a temperature 30°C higher than the Af point (martensitic reverse transformation end temperature). Those that completely shrunk to the original coil length of 50 mm when heated were marked with an ○, and those that did not completely shrink to the original coil length of 50 mm were marked with an x.

As is clear from Table 1, the alloy of the present invention exhibits a tensile strength of 96 to +1.2 kgf/mm, and has good cold workability and good shape memory. I understand that.

On the other hand, the comparative alloys hr 8.9.10.11, in which the N1, Si, and P contents are lower than the composition range of the present alloy, have good shape memory properties, but cold workability is not improved in any of them. It can be seen that the tensile strength of the alloy of the present invention is also inferior when compared with an alloy with a similar amount of A4. Moreover, the ratio J-shape alloy 1' has a higher N1, Sl, and P content than the composition range of the alloy of the present invention!
It can be seen that although cold workability is sufficient for i I 2 J 3.14, shape memory properties are poor in both cases.

As detailed above, the alloy of the present invention has excellent cold workability,
Cu-Zn- has both tensile strength and sufficient shape memory.
It exhibits remarkable effects as an Ad-based shape memory alloy.

Claims (1)

[Claims] AA! 0.0 5-1 0. Owt%, Zn 9.
0 $~4 0. Owt%, Ni0.30-2. Q
Including wt chi, at least one of sl, p 0.0
Cu − containing 1 to 0.50 wt% and the remainder being Cu −
Zn--Al type shape memory alloy.