PL157462B1 - Copper alloy - Google Patents

Abstract

The invention relates to a copper alloy which is characterised by a shape memory, high tensile strength, high extension capability and very high degree of shape recovery. There is a variety of shape memory alloys known worldwide, including those based on copper. These include brass. One of the well known types of brass is aluminium brass containing by weight around 14% of zinc, around 18% of aluminium or 23-24% of zinc and 78% of aluminium /N. Mantel, R. Rapationi, G. Guenin - Revue de Metalurgie, February 1988, p. 97/. Another known type of an alloy contains about 26% by weight zinc and about 4% by weight aluminium /D. A. Admyana - Wire Journal International, April 1984, p. 52/ In comparison to the traditional nickel-titanium alloys they have one basic disadvantage - low mechanical properties. Their extension capability does not exceed 250 Mpa. The other bad point is that they are difficult to be formed while cold. In order to improve these properties they are supplemented with elements like vanadium /K. Enami, N. Takimoto, S. Nenna - Journal de Physique 43. 1982. 785, append. 12/, cerium, chrome, zirconium /Y. Ikami, K. Marakami, K. Mishima - Journal de Physique 43. 1982. 785, append. 12/ or a special heat treatment is applied /S. M. White, J. M. Cook, W. M. Strobbs - Journal de Physique 43. 1982. 779, append. 13/. The additives listed above or the heat treatment reduce partly the faults, however, their application implies technological difficulties. The aluminium brass being subject of this invention is characterised by the fact that it contains: 8-30% of zinc, 2.5-18% of aluminium, 0.001-1.5% of titanium, 0.001-0.5% of boron, the rest is composed of copper and allowable impurities amounting up to 0.8%, with the reservation that the sum of contents of titanium and boron is not larger than 1.5%. This alloy can be produced by known methods of melting and static, continuous and semi-continuous casting followed by plastic heat working including extrusion, rolling, open or closed die forging, plastic cold working including rolling, drawing and deep drawing and heat treatment by hardening, toughening and annealing.

Description

REPUBLIC POLAND PATENT DESCRIPTION 15 * 7462 0 Additional patent to patent no --- Reported: 89 33 14 (P. 273272) Priority - Int. Cl. ^s C22C 9/04 C22C 9/01 OFFICE PATENT Application announced: 89 1 ° ⁰² READUlft 0 LHA RP Patent description published: 1993 03 31

Creators of the invention: Zbigniew Bojarski, Henryk Morawiec, Kazimierz Joszt, Mirosław Lachowski

The holder of the patent: Institute of Non-Ferrous Metals :,

Gliwice / Poland /

COPPER STOP

The subject of the invention is a shape memory copper alloy with high tensile strength and high elongation and a very high degree of shape recovery.

So far, a number of types of shape memory alloys, also based on copper, are known worldwide. Brass is also among them. Of these, known are aluminum brasses containing by weight about 14¾ zinc and about 18¾ aluminum or 23-24¾ zinc and 78¾ aluminum (M. Mantel, R. Rapacioli, G. Guenin - Revue de Metalurgie, February 1988, p. 97). Brass with a weight of about 26¾ zinc and about 4¾ aluminum (0. A. AdnyanaWire Journal International, April 1984, p. 52) is also known. Compared to classic nickel-titanium alloys, they have a basic disadvantage, namely low mechanical properties, their tensile strength does not exceed 25D MPa. Their second disadvantage is the fact that they are difficult to process when cold. To improve these properties, elements such as vanadium / K.Enami, N.Takimoto, S.Nenno - Journal de Physicpje 43. 1982. 773 suppl.12 /, cerium, chromium, zircon / Y.Ikai, K. Marakami, K. Mishima - Journal de Physicje 43.1982, 785, suppl.12, or uses a special heat treatment / SM White J.M.Cook, W.M.Strobbs - Journal de Physi | ue 43.1982, 779 suppl. 12 /. These additives or a special heat treatment slightly reduce these inconveniences, but their introduction causes technological difficulties.

Aluminum brass according to the invention is characterized by the fact that it contains by weight: 8-30¾ zinc, 2.5-18¾ aluminum, 0.001-1.5¾ titanium and 0.001-0.5¾ boron, the rest is copper and permissible impurities in the amount of up to 0.8 ° -i, with the sum of the titanium and boron content not greater than 1.5¾.

This alloy can be produced by known methods by melting and static casting, semi-continuous or continuous casting, followed by hot forming by extrusion, rolling, open die forging or die forging, cold working by rolling, drawing, deep drawing and heat treatment such as hardening. , quenching or annealing.

157 462

In order to obtain good strength properties, very good hot formability, sufficient cold formability and a high degree of shape recovery, the alloy according to the invention preferably comprises 11-27% by weight of zinc and also 3-10% by weight of aluminum. Preferably also the alloy contains 0.2-0.% Wt. Of titanium. It also preferably contains 0.04-0.3% by weight of boron and most preferably has a total of not more than 1% by weight of boron and titanium. This alloy is produced by known methods.

An example of an alloy according to the invention is given below.

An alloy containing 8.1% by weight of aluminum, 14.6% of zinc, 0.3% of titanium and 0.065% of boron is melted in an electrifying induction furnace, the rest is copper and impurities. Round billets with a diameter of 205 mm are cast from the alloy by the solid method. After cutting, these ingots are heated to a temperature of 850 ° C and wires with a diameter of 6 mm are pressed out on a press. The obtained wires are drawn using thread and heat treatment. The finished wires are quenched from a temperature of 700 ° C to ice water. The wires made in this way have a tensile strength of more than 350 MPa with an elongation of more than 5%, and above all, they are characterized by a very high shape recovery coefficient.

Claims (6)

i. A copper alloy containing in addition to copper, zinc and aluminum, further comprising titanium and boron, the titanium content by weight being 0.001-1.5%. boron 0.001-0.5%, zinc 8-30%, aluminum 2.5-18%. and the sum of the titanium and boron content is not more than 1.5%, the rest is copper and permissible impurities in an amount up to 0.0%. 2. The alloy according to claim 1, no t 3. The alloy according to claim 1, significant 4. The alloy according to claim 1, significant 5. The alloy according to claim 1, significant 6. The alloy according to claim 1, significant titanium is not more than 1% by weight. [mu] m that it contains 11-27% by weight zinc, in that it contains 3-10% aluminum. that it contains 0.04-0.3 wt.% boron, that it contains 0.2-0.% wt. titanium, with the total content in the boron alloy and Department of Publishing of the UP RP. Circulation of 90 copies