Toshio Sakuma1,, Yuji Mihara2,, Yasuo Ochi2 and Kiyoshi Yamauchi3
1Central Research Institute of Electric Power Industry
In many cases that shape memory alloys are applied to the engineering and medical fields, it is necessary to deform them in martensitic phase. However, if the slip-deformation occurs, shape recovery does not occur completely even if heated up above Af. It is reported that transformation temperatures are changed by pre-deformation and in constrained strain condition. Therefore, it is important to investigate the relationship between the pre-deformation and the deformation and transformation characteristics such as recovery stress, transformation temperatures and so on. The purpose of this work is to clarify the influence of pre-deformation on recovery strain, recovery stress and transformation temperatures in a Ti-Ni alloy. The specimens are Ti-50 at%Ni annealed at 1103 K for 60 s. The variation of recovery strain, recovery stress and transformation temperatures by pre-straining is investigated experimentally. The variation of transformation and deformation behavior by pre-straining will be discussed in relation to the volume fraction of slip-deformed martensite.
shape memory alloy, Ti-Ni alloy, pre-strain, recovery stress, recoverable strain, transformation temperature, volume fraction of slip-deformed martensite
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