EFFECTS OF TRAINING ON THE SHAPE MEMORY BEHAVIOR OF CU-ZN-AL ALLOYS

The successful use of the TWME is still hampered by misunderstandings and lacking information about the training and the resulting two way memory effect (TWME). Experimental results are presented on the stability and reproducibility of the TWME and the relationship of those characteristics with the training procedure. In contrast to what is generally accepted, the TWME can withstand considerable opposing stresses during the martensitic transformation, i.e. the TWME can do work during cooling. Related to this, recovery stresses are generated during cooling when the TWME is impeded. It is also shown that the maximum attainable TWME diminishes when the training is preceded or interrupted by thermal transformation cycles. Those results are explained by considering training as the process of stabilizing a particular martensite formation path and thermal cycling as training of a self-accommodating path.