Abstract
The thermal effect associated with the formation and reversion of stress-inducedβ′ martensite has been studied in single crystals ofβ 1-CuAlNi. The maximum temperature increase for theβ 1 →β 1′ transformation in a specimen at room temperature ranged from 1.2°C at a strain-rate of 0.025 min−1 to 14°C at a strain-rate of 25 min−1. The large temperature increase is due to lower heat losses at the high strain-rates and a closer approach to adiabatic conditions. The thermal effect for theβ 1 →β 1 transition was somewhat larger and believed to be due to the different directions of motion of the single transformation interface. A method has been developed which correlates the thermal effect at infinite strain-rate with the entropy change of the transformation resulting in a value of δSβ’1 Β1 = − 1.20 J/mol · K. This result is in good agreement with the entropy changes of −1.18 ± 0.17 J/mol · K calculated from the Clausius-Clapeyron equation. The variation of the thermal effect with specimen temperature (d|δT|/δT) was 0.04 ± 0.01, and could be explained by assuming a constant entropy change for the transformation at different temperatures.
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Rodriguez, C., Brown, L.C. The thermal effect due to stress-induced martensite formation in Β-CuAlNi single crystals. Metall Trans A 11, 147–150 (1980). https://doi.org/10.1007/BF02700450
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DOI: https://doi.org/10.1007/BF02700450