X-ray diffraction analysis of Ti-18 mol % Nb based shape memory alloys containing 3d transition metal elements

The effect of 3d-transition-metal alloying on the phase constitution of Ti-18 mol%Nb based shape memory alloys was investigated by Xray diffraction analysis (XRD) at room temperature. The baseline binary Ti-18 mol%Nb alloy (called Binary) and ternary Ti-18 mol%Nb-3 mol%X alloys (X = V, Cr, Mn, Fe, Co and Ni, called 3X) were fabricated by Ar arc-melting method, followed by homogenization at 1273 K for 3.6 ks. These alloys were cold-rolled with 30% and 98% reduction in thickness. Some specimens from 98% cold rolled material were solution treated at 1273 K for 1.8 ks and quenched in water. It was found that the phase present in the solution-treated and quenched Binary and 3V was alpha martensite phase and that of the other alloys was beta phase. No other phase or ordering was confirmed in these baseline and 3X alloys. The lattice parameter of beta phase showed a good correlation with the Goldschmidt atom radius of the ternary alloying metals. It was confirmed that (1) almost same type of deformation texture was formed in beta phase materials regardless of the alloying metals but that (2) the development of recrystallization texture was suggested to be different depending on the alloying metals.