刑狀記憶合金의 擬彈性 機構에 關한 硏究 = Mechanism of Pseudo-Elasticity in the Cu-Based Shape Memory Alloy

다국어 초록 (Multilingual Abstract)

The pseudo-elasticity in the ternary alloy (Cu_74 Zn_20)Al_6 is investigated experimentally and the results are interpreted in terms of the continual mechanical twinning.
Measured are the effects of temperature on such as stress-strain curve, critical shearing stress, twinning stress and load concentration. Also the relation between shearing stress and strain rate, and cyclic strain-stress curve are obtained experimentally. The experimental results of the present study are in good agreement with the Bolling-Richman theory which is a model-independent description of mechanical twinning.
The transformation temperature of (Cu_74 Zn_20)Al_6 alloy are M_f : 333°K, Ms : 358°K, As : 353°K, and A_f : 393°K. The stress-strain curve shows clearly the pseudo-elasticity which is related with the mechanical twinning generated in the sample. The critical shear stress has the positive temperature-dependence indicating that the dominant process in the sample is a deformation by mechanical twinning rather than the deform by slip. Also, the temperature effects on work hardening, the relation between twinning stress and load concentration, and other measurements all indicate that the continual mechanical twinning is the main cause of the pseudo-elasticity in the Cu-based memory alloy (Cu_74, Zn_20)Al_6.