Transformation behavior of Ti–Ni–Cu–Mo alloys

Transformation behaviors of Ti–(47 − x)Ni–3.0Cu– xMo (at.%) ( x = 0.3–1.0) alloys were investigated by means of electrical resistivity measurements and X-ray diffraction. The alloy with Mo-content of 0.3 at.% transformed in one-stage i.e., B2–B19′, while the alloy with Mo-content of 0.5 at.% transformed in two-stage i.e., B2–R–B19′. The alloys with Mo-content more than 0.7 at.% transformed in three-stage i.e., B2–R–B19–B19′. M s (the B19′ martensite formation temperature), M ′ s (the B19 martensite formation temperature) and T R is (the R phase formation temperature) decreased with increasing Mo-content. The decreasing rate of M s, M ′ s and T R with increasing Mo-content were found to be 60 K/at.% Mo, 27 K/at.% Mo and 20 K/at.% Mo, respectively. The Mo-content dependence of transformation behaviors in Ti–(47 − x)Ni–3.0Cu– xMo alloys were ascribed to the different Mo-content dependence of M s, M′ and T R.