Tension - Compression Asymmetry in Co_(49)Ni_(21)Ga_(30) High-Temperature Shape Memory Alloy Single Crystals

摘要

This paper reports on the tension-compression asymmetry of [001]-oriented Co_(49)Ni_(21)Ga_(30) single crystals at elevated temperatures. Maximum strains of -4.8 % and 8.6 % in compression and tension, respectively, were found. A linear Clausius-Clapeyron relationship was observed for both stress-states where the smaller slope in tension resulted in a significant increase of the phase transformation temperatures with stress, which reached 180 °C under a constant stress level of 150 MPa. In addition, the material demonstrated a large pseudoelastic temperature range of about 300 °C under both stress state conditions. The results in this study unequivocally indicate the potential of these alloys for applications where elevated temperatures and stress levels prevail.