The effect of indentation temperature and load on mechanical characterization and transformation behavior of high temperature Ti-V-Al-Cu shape memory alloy

Abstract

The effects of temperature and load on the indentation-induced mechanical characterization of the Ti-V-Al-Cu alloy were investigated. Also, the effects of heating/cooling rate and thermal cycle on the transformation temperatures were examined. Thermally-induced reverse martensite phase transformation was detected from α” martensite phase to β austenite phase during heating. Transformation temperatures decreased with the heating rate and thermal cycles. High temperature microindentation tests were conducted at both 450 °C (>As) and room temperature (24 °C) at four different loads to determine indentation-induced mechanical properties and deformation behaviors. The deformation mechanism of the Ti-V-Al-Cu alloy at 450 °C was found to involve the stress-induced martensite transformation associated with superelasticity and partially causing transformation from β phase to α” phase. The superelastic and total recoverable strains are 48% and 62% at 8000 mN load for 450 °C and are the highest values obtained for this study. The results show that the effect of load on the deformation mechanism of the same Ti-V-Al-Cu alloy at different temperatures is different and positively affects elastic recovery at 450 °C while causing plastic deformation at room temperature.