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Properties of Thermally Treated CuZn27Al3 Shape Memory Alloy

The work analyses the behaviour of thermally treated CuZn27Al3 shape memory alloys. The alloy is betatised and quenched from the temperatures in the range of ϑβ = 600°C to ϑβ = 800°C. The properties of materials are analyzed by means of differential scanning calorimetry, micrographic testing, testing of mechanical properties and pseudo-elastic effect. The results indicate significant dependence of classical and specific properties on thermal treatment temperature, particularly if ϑβ < 700°C. The change in transformation temperatures, hardness, mechanical resistance determined by static tensile loading as well as specific pseudo-elastic elongation is the consequence of the occurrence of subboundaries and formation of α-crystal mixes, thus changing the chemical composition of austenite. Betatisation at higher temperatures (700≤ϑβ≤800°C) contributes to martensitic transformation reducing the driving force necessary for the transformation in the form of conducted heat in thermally induced transformation i.e. required stress for mechanically induced martensitic reaction with simultaneous increase of pseudo-elastic shape memory, as well as the reduction of total mechanical resistance of the alloy.

CuZnAl alloy; shape memory; thermal treatment; transformation temperatures;

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