IMPROVEMENT OF MECHANICAL AND SHAPE MEMORY PROPERTIES OF Ti-50Pt HIGH TEMPERATURE SHAPE MEMORY ALLOYS BY ADDITION OF GROUP IV ELEMENTS

摘要

Near-equiatomic Ti-Pt intermetallic alloys exhibit very high(e.g. above 1200K)transformation temperatures. However, binary Ti-Pt intermetallic alloys exhibit negligible shape recovery and low strength due to low critical stress for slip deformation. Then, in this study, effects of 5atomic percent addition of group IV transition elements on room temperature to high temperature strength, shape recovery and transformation temperatures of Ti-50at%Pt were compared. Strength was decreased and ductility was increased by increasing testing temperature. Ti-50Pt-5Hf exhibited higher strength at room temperature compared to Ti-50Pt-5Zr and Ti-50Pt. However, strength of Ti-50Pt-5Zr was found much higher than Ti-50Pt-5Hf and Ti-50Pt when tested at 50K below M_f. Transformation temperatures were decreased and shape memory effect was improved by addition of group IV elements.