Martensitic Transformation in TiPd–Cr Alloys

抄録

The crystal structures, internal structure of the martensitic phases and the effect of chromium addition on the martensitic transformations on the TiPd alloys were investigated by elecrical resistivity measurements and electron microscope observation. It was found that the chromium addition is very effective in reducing the Ms temperature from about 800 K for the stoichiometric TiPd alloy to liquid nitrogen temperature with increasing chromium content, in both the alloys Ti₅₀Pd_50-x Cr_x(x=2 to 10 at%) and Ti₅₄Pd_46-x Cr_x(x=2 to 6 at%). In the chromium-added alloys, the 9R martensite phase and a peculiar intermediate incommensurate phase appear besides the twinned B19(2H) martensite, like in the case of the TiPd–Fe alloys. The internal structure of the 9R martensite was found to be {114}_9R twins which corresponds to {128}_18R type twin of the 18R martensite phase of the Cu–Al alloys. The features of the incommensurate phase, i.e., large incommensurability of superlattice reflections, its dependence on the alloy composition, configuration of variants are quite the same as those in the TiPd–Fe alloys.