Energetic evaluation for inducing the thermoelastic martensitic transformation by mechanical stress in Cu–Zn–Al single crystals

Abstract

The ease with which the thermoelastic martensitic transformation is induced by mechanical stress in four Cu–Zn–Al single crystals with pseudoelasticity effect has been studied. Mechanical tests have been carried out at different temperatures, and show an increase in the slope of the stress–strain curve corresponding to the β → stress-induced martensite (SIM) transformation with an increase the test temperature. The relationship between the slope and the temperature follows a power law equation, depending on the chemical composition, transformation temperature and defect density as the most important factors. The stored energy has been calculated from the stress–strain curves as the area under the curve when SIM transformation is finished, and the friction energy as the area of the mechanical hysteresis, for four single crystals of Cu–Zn–Al alloys. The results indicate that when the M s of the alloy increases, a decrease in stored energy can be observed. Also, the increase of the test temperature produces an increase in the stored energy.