Martensitic Transformation of Cold-Rolled and Annealed Ti<SUB>50</SUB>Ni<SUB>40</SUB>Cu<SUB>10</SUB> Shape Memory Alloy

作者：Kai-Nan Lin, S.K. Wu, Ling-Mei Wu · 发表于：MATERIALS TRANSACTIONS · 年份：2009 · DOI：10.2320/matertrans.m2009254 · 被引用次数：12 · 研究领域：Shape Memory Alloy Transformations、Titanium Alloys Microstructure and Properties、Magnetic and transport properties of perovskites and related materials

This study investigates the cold-rolling effect on the formation of Ti(Ni,Cu)2 precipitates and on the change of transformation temperatures for hot-rolled (HR)/annealed (HRA) and HR/cold-rolled/annealed (CRA) Ti50Ni40Cu10 specimens. Particle-like Ti(Ni,Cu)2 precipitates formed in CRA are more numerous and smaller than plate-like Ti(Ni,Cu)2 precipitates formed in HRA and thus the hardness and storage modulus of the former are higher. The broader transformation peaks exhibited in CRA compared to HRA can be explained by the assistance of the tensile stress field around the plate-like Ti(Ni,Cu)2 precipitates. The different transformation peak temperatures of B2→B19 and B19→B19′ in between HRA and CRA result from the different Cu content in the matrix. A relaxation peak appears in CRA with the activation energy of 64.4 kJ/mol. The cold-rolling process may be an important factor in enhancing the appearance of the relaxation peak.