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Tension - compression asymmetry in Co49Ni21Ga30 high-temperature shape memory alloy single crystals

authors:T. Niendorf, J. Dadda, J. Lackmann, J.A. Monroe, I. Karaman, E. Panchenko, H.E. Karaca, H.J. Maier
publication:published in Materials Science Forum, Volumes 738 - 739


This paper reports on the tension-compression asymmetry of [001]-oriented Co49Ni21Ga30 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.