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Transformation temperatures and mechanical properties of ausforming treated Cu-Zn-Al shape memory alloy

Hot rolling of CuZn27Al4 shape memory alloy influences “classical” material properties as well as specific properties related to shape memory behaviour. Rolled and quenched alloy (ausforming treatment) shows hardening proportional to the value of introduced deformation as a result of formation of defects such as dislocation and deformed boundaries of austenitic grains. Regardless of the resulting changes, the alloy shows full reversible transformability of the austenitic structure. Specific behaviour of ausforming treated Cu-Zn- Al alloy in the field of thermal transformation cycle has been analysed by means of differential scanning calorimetry supported by tensile testing. The transformation behaviour of the alloy shows significant dependence of the amount of plastic deformation introduced by hot rolling. The ausforming treatment reduces all transformation temperatures of the austenitic- martensitic reaction, thus expanding the temperature range of super-elasticity. Despite the hardening effect which occurs after rolling, the thermo-mechanically treated CuZn27Al4 alloy retains the super-elasticity, therefore an optimal combination of strength and transformation behaviour can be achieved by the ausforming treatment, which is also required in the majority of applications for these alloys.

Cu-Zn-Al SMA, Martensite transformation, Differential scanning calorimetry, Ausforming treatment, Mechanical properties, Super-elasticity

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