A study on the pseudoelasticity of low temperature aged and thermomechanically treated Ti-51.5 at.% Ni shape memory alloy

作者：Karimzadeh Mehrdad^*; Aboutalebi Mohammad Reza; Salehi Mohammad Taghi; Abbasi Seyyed Mahdi; Morakabati Maryam

来源：International Journal of Materials Research, 2014, 105(12): 1173-1178.

DOI：10.3139/146.111136

• NiTi shape memory alloys
• R-phase
• Stress-induced transformation
• Pseudoelasticity

The aim of the present work is to investigate the effects of low temperature aging and thermomechanical treatments on the transformation and deformation behavior of an Nirich NiTi alloy. One sample of solution treated Ti-51.5 at.% Ni shape memory alloy was aged at 300 degrees C for 1 hr. The other solution annealed sample, was firstly cold rolled to a reduction of 20% and then aged at 300 degrees C for 1 hr. Applying these treatments, samples showed R-phase transformations in the absence of B19 ' phase formation according to differential scanning calorimetry curves. By applying 20% cold reduction in area prior to aging, almost complete recovery of strain was observed and pseudoelasticity improved significantly compared to the conventional aged sample. Results of thermal analysis and tensile tests suggest that the observed pseudoelasticity for the thermomechanically treated sample can be due to stress-induced formation of R-phase. It is proposed that if stress-induced transformation of B19 ' phase does not take place, stress-induced transformation of R-phase can extend to higher than 1% strain. Hence, pseudoelastic behavior due to this transformation can be observed.

• 出版日期2014-12