CHANGES OF MEMORY CHARACTERISTICS OF Cu-Zn-Al SMA UNDER LOADED THERMAL RECYCLING AND A DESIGN FOR A MANUAL AND AN AUTO TEMPERATURE-CONTROL VALVE

摘要

It is well known that the decrease of Shape Memory Effect (SME) and shift of transformation temperature during thermal recycling limit practical uses of Cu-Zn-Al Shape Memory Alloys (SMAs). Recently, we studied the influences of thermal recycling under constant load as well as under varying load (with a spring) on SME and transformation temperatures. We were surprised to find that the decrease of SME ameliorates greatly under loaded thermal recycling, e.g., the recovery rate can be kept to 82% after 12,000 thermal recycling under a constant load of 75 g. Moreover, the transformation temperatures of A_s and A_f change very little. We thus designed a kind of manual and auto temperature-control valve with a spring made of a Cu-Zn-Al SMA (Chinese Patent ZL.96247617-X).