Affiliations: [a] Division of Materials Engineering and ERI, Gyeongsang
National University, 900 Gazwadong, Jinju, Gyeongnam 660-701, Korea | [b] School of Electrical Engineering and Computer Science,
Kyungpook National University, 1370 Sankyukdong, Daegu 702-701, Korea | [c] School of Mechanical Engineering, University of
Western Australia, Crawley, WA6009, Australia. Tel.: +82 55 751 5307; Fax: +82
55 759 1745; E-mail: tahynam@gsnu.ac.kr
Abstract: Phase transformation and deformation behavior of
temperature-gradient annealed (TGA) equiatomic Ti-Ni alloy wires were
investigated by means of differential scanning calorimetry (DSC), thermal
cycling under constant load and tensile testing. TGA treatment in a temperature
range of 658∼823 K caused variations of 10 K in T_{R}*
and 14 K in M_{s} along the length of the specimen.
Temperature dependence of specimen elongation (dε/dT) of TGA
treated Ti-Ni alloy wires was in the range of 0.12∼0.43%/K depending on
annealing temperatures. The lowest dε/dT was obtained in the sample
annealed in the temperature range of 658∼713 K. The stress for martensite
reorientation remained nearly constant for the specimen annealed in the
temperature range of 740∼823 K, whereas that for the specimen annealed in
the temperature range of 658∼740 K increased continuously with increasing
strain.
Keywords: Ti-Ni shape memory alloy, martensitic transaformation, temperature gradient annealing, actuator, proportional control
