The Effect of Thermal Cycling on the Thermo-Elastic Martensitic Transformation in a Cu-Zn-Al Alloy.

摘要

The effect of thermal cycling between the M(f)-A(f) on the thermal hysteresis, temperature dependence, and the morphology of the martenistic transformation in a Cu-Zn-Al alloy was studied. The hysteresis behavior of the cyclic transformation, as characterized by following the change in electrical resistivity accompanying the transformation changed in two respects: First, the M(s) and A(f) temperature shifted to higher temperatures while the M(f) and A(s) temperatures remained constant, secondly, the amount of martensite undergoing cyclic transformation decreased. These changes appeared to saturate at 300 cycles and could be partly recovered during room temperature aging. The morphology and mode of transformation also changed. During the first few cycles, transformation occurred in two simultaneous ways: (1) as martensite plates which are observed to grow and thicken in a continuous manner; and (2) as plates which form in a burst process. After 60 cycles no burst type transformation occurred during cooling and plate growth and thickening was stepwise. (Author)