JPS5970742A - Shape memory copper alloy - Google Patents

Abstract

PURPOSE:To make the resulting titled alloy inexpensive and easy to cut and to enable the melting and heat treatment in the air by providing a specified composition consisting of Mn, Zn and Cu. CONSTITUTION:This shape memory Cu alloy consists of, by weight, <=12% Mn, 26-44% Zn and 62-65% Cu. Al may be added to the alloy so as to provide a composition consisting of <=12% Mn, <=3% (X%) Al, (26-4X)-44% Zn and (62+3X)-(56-X)% Cu. The working (transformation) temp. of the ternary alloy is usually about -150 deg.C- room temp. The working temp. can be raised up to a temp. above room temp. by adding Al.

Description

[Detailed description of the invention] The present invention relates to a novel copper-based shape memory alloy.

In general, shape memory alloys have shape memory effects, superelasticity, and vibration damping effects, and various uses are being developed using these properties. Shape memory effect refers to an article made of an alloy with a specific composition that undergoes shape memory heat treatment, deforms in a certain temperature range, and then when heated above a predetermined temperature, the shape of the article changes to its original shape. This is a phenomenon of returning to the shape.

In other words, it is a phenomenon in which the shape is unidirectionally or reversibly restored between the shape at the high temperature side and the shape at the low temperature side across the transformation temperature range of the alloy, and is caused by thermoelastic martensitic transformation. It is said that then. In addition, superelasticity means that the martensitic phase, which has already been described due to stress, cannot exist thermodynamically stably in the temperature range at the time of deformation. This refers to the phenomenon of complete recovery. Furthermore, the vibration-proofing effect is said to be due to the fact that the layered martensite phase absorbs vibration energy.

As shape memory alloys, Ti-Ni alloy, Ni-
Cu-Zn alloy, Cu
-Zn-Al alloy, Cu-AI-Ni alloy, C
u-Al-Be alloy etc. are known, and among these alloys, the alloys that have been put into practical use are mainly "l'1-Ni alloy, Cu
-Zn-Al alloy and Cu-Al-Be alloy.

However, although Ti-Ni alloy has excellent properties, it is expensive because it mainly contains Ti and Ni.
In addition, since it is an alloy containing active 1, it has a manufacturing disadvantage in that melting and heat treatment must be performed in a vacuum.
Another drawback is that cutting is extremely difficult.

On the other hand, Cu-Zn-Al alloy and Cu-A I-B
Steel-based alloys such as e-alloys are inexpensive raw materials, can be melted and heat treated in the atmosphere, and are easy to cut, so they are expected to be used as materials to promote the practical use of shape memory alloys. There are high expectations.

However, these copper-based alloys have poor toughness because they harden due to containing a large amount of Al.
There is a drawback that castability is reduced.

Therefore, in copper-based alloys having the above advantages, A
At present, the discovery of a new additive element that can replace I or reduce A1 is awaited.

The inventor of the present invention took note of the current situation and conducted intensive research to develop a new copper-based alloy that eliminates the above-mentioned drawbacks of this yuzu alloy, especially copper-based alloys, and found that the conventional usable temperature range was excessively low. Therefore, by adding a specific amount of Mn to the Cu-Zn alloy, which was not practical, the usable temperature range is increased and it can be put into practical use.
The temperature range can be adjusted over a wide range by adding a small amount of AI to the alloy, and these Cu-Zn-M
Both the n-alloy and the Cu-Zn-Mn-A I alloy show good shape memory effects, and by containing no or only a small amount of AI, they are superior to conventional copper-based alloys. Toughness is significantly improved compared to alloys.
The present inventors have discovered that the present invention has excellent castability and good castability, and has completed the present invention.

That is, the present invention provides a copper-based shape memory alloy characterized by a weight of Mn of 12% by weight or less, Zn of 26 to 44 weight 1+t:%, and Cu of 62 to 56 weight%, as well as Mn of 12 weight% or less and A13 weight of % or less. (X weight %), Zn(26-
4x)~44 heavy plate% and Cu(62+8X)~(56-
X) It relates to a copper-based shape memory alloy characterized in that it consists of % by weight.

In the Cu-Zn-Mn ternary alloy of the alloys of the present invention, the Mn content is 12% or less, preferably 0.5 to 10%.
Heavy nail % nail shape n is 26-44% by weight, preferably 28-41
．． 5% by weight, and the total amount of Mn and Zn is 38-44% by weight (
Weight Cu is 62 to 56% by weight), preferably 38 to 42% by weight. When Mn is not contained, the Mn content is 1
If the double claw shape is exceeded, if Zn is outside the above range, or if the total amount of Mn and Zn is outside the above range,
In either case, the operating temperature for shape recovery of the alloy is extremely low, so they are of little practical use. The composition range of the Cu-Zn-Mn ternary alloy of the present invention is illustrated in FIG. 1.

That is, Mn is 0% by weight (0 is not included, so it is shown by a broken line) and 122 times, and Mn + Z 11 is 38% by weight.
Range 5 surrounded by four straight lines showing double claw shape and 44 double star shape
It is surrounded.

The above ternary alloy of the present invention has an operating (transformation) temperature of -
The operating temperature is about 150° C. to room temperature, but by adding A1 to this, the operating temperature can be raised to above room temperature. Furthermore, the composition range exhibiting shape memory behavior can be expanded by adding AI.

It was experimentally confirmed that this could be obtained.

Therefore, Cu-Zn-Mn-AI of the present invention
In the quaternary alloy, Mn is 122 weight or less, preferably 0.5 to 10 weight i1%, AI is 8 weight % or less (X weight %), preferably 0.2 to 2.5 weight %, Zn (26-4x) ~ 44 double claw shape or (28-4x
) ~ (48,5-4x)% by weight, the total amount of Mn and Zn is (88-4x) ~44% by weight [i.e., Cu is (62+
8x) ~ (56-x') heavy prefecture%] Preferably (38-4
x) to (44-4X)% by weight. If any of these ranges other than AI falls outside the range, the operating temperature for shape recovery will be significantly lower, resulting in poor practicality.

Furthermore, if the AI exceeds 3-fold Jiζ%, the toughness and castability will decrease. Present invention Cu-Z n -M n -A I
The composition range of the quaternary alloy is as follows: If AI containing ji+ is shifted from X weight %, Mn is 0 weight (%, M n is 12 weight 1%, Zn
+Mn is 44 double claw type and Zn -1-Mn is (88
-4x) weight% range surrounded by four straight lines, -
As an example, cases where AI is 1.2 and 3% by weight are shown in Figures 2.3 and 4.

``Double A1 addition effect, i.e., the operating temperature'' - increase and expansion of the composition range can be achieved not only with AI but also with Ga, Sb, Si,
I n.

Similar results can be expected by adding elements such as Sn.

In general, copper-based alloys, including the alloy of the present invention, have the disadvantage that crystal grains tend to grow due to high-temperature heating during the manufacturing process, and fatigue strength is inferior due to the crystal grains becoming smaller. A method separately announced by the inventor (Osaka Prefectural Industrial Technology Research T9'1lAA Notice, No. 81, P, 17.1982)
) can be improved. That is, the Cu-Z n of the present invention
The -Mn ternary alloy or the quaternary alloy containing A1 has large crystal grains, sometimes 1 mm or more. but,
By adding elements such as B and Zr to the alloy of the present invention in an amount of about 0.3% by weight or less, crystal grains are significantly refined. In this case, even if B or Zr is added alone, the grain size becomes extremely fine, but when both B and Zr are added in combination, the grain size becomes even finer. For example, 0.01% by weight of B and 0.2ii
% of Zr, the crystal grains become fine to about several tens of microns, and the fatigue strength is significantly improved.

The alloy of the present invention is prepared by blending CuSZn, Mn, or these with A1, and optionally B5Zr, etc. in a predetermined amount of H (blending) to form an alloy according to a conventional method, and then annealing and processing to obtain a desired shape. The metals are rapidly cooled to form a shape memory alloy. At this time, each metal may be used alone or partially alloyed in advance, such as a Cu-Mn master alloy.

Further, unlike the I'1-Ni alloy, it is not necessary to manufacture it in a vacuum, and it can be suitably manufactured in the atmosphere.

The alloys of the present invention thus obtained, that is, the Cu-Zn-Mn ternary alloy and the Cu-Zn-Mn-Al quaternary alloy, are both new copper-based shape memory alloys that develop a B-phase structure at high temperatures. Within the specific composition range indicated above, the shape memory effect, superelasticity, and vibration damping effect are fully exhibited. The alloy of the present invention has a wide usable temperature range and high utility value, and
Since it has excellent toughness, it has good workability and also good castability.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Copper, zinc, and copper-manganese mother alloy were mixed in a predetermined ratio and filled into a crucible, then vacuum sealed in quartz glass and kept in an electric/air furnace at 1100°C for 1 hour to prepare the samples of the present invention and comparison. A ternary alloy was produced.

The thus produced alloy was annealed and processed to form a desired shape, heated to region B, and then rapidly cooled at a sufficient cooling rate to produce a shape memory alloy. Table 1 below shows the composition and functional properties of typical alloys of the present invention and comparative alloys produced by the above method.

Regarding the above-mentioned alloy 8 of the present invention containing 86% by weight of internal rust and 3% by weight of manganese, each transformation temperature was measured by the fil: non-resistance measurement method, and it was found that Ms.
Mf, As and Af (Ms is the starting temperature of martensitic transformation from the matrix, Mf is the finishing temperature, As is the starting temperature of reverse transformation, and Af is the finishing temperature) are about -55 and -, respectively. 85, -75, and -45°C, and hysteresis peculiar to shape memory alloys is observed, and when heated after being deformed at a temperature below Mf (approximately -100°C), As,
It was observed that the shape recovery started and ended around the temperature corresponding to Af.

In this example, since this was a trial production, a method of vacuum sealing in quartz glass was used, but it can be suitably produced in the atmosphere when being transferred.

Example 2 A quaternary alloy of the present invention and a comparison were produced in the same manner as in Example 1 by blending copper, zinc, a copper-manganese master alloy, and aluminum in predetermined amounts. Table 2 below shows the composition and functional properties of typical examples containing 1.2 or 3% by weight of aluminum.

As is clear from Tables 1 and 2, the alloys of the present invention all exhibit good shape recovery behavior, whereas the comparative alloys outside the specific composition range of the present invention Except for No. 11, none showed shape recovery behavior. Comparative alloy 11 is a conventional Cu-Zn-Al alloy and has poor workability due to poor toughness, whereas invention alloys 8 to 8 and 11 to 14 have excellent toughness and good workability. One thing is clear.

[Brief explanation of the drawing]

FIG. 1 shows the composition range (shaded area) of each element of the Cu-Zn-Mn ternary alloy of the present invention. 2.8 and 4
The figure shows the composition range (hatched area) of other elements when AI is 1.2 and 8% by weight in the Cu-Zn-Mn-Al quaternary alloy of the present invention. (that's all)

Claims (1)

[Claims] 1. Mn 12% by weight or less, Zn 26-44% by weight, and C
A copper-based shape memory alloy comprising 62 to 56% by weight of u. 2. It is characterized by comprising 12% by weight or less of Mn, 8% by weight or less of Al (referred to as X weight%), Zn (26-4x) to 44% by weight, and Cu (62+8x) to (56-x) by weight. Copper-based shape memory alloy.