Abstract
Ti-Ni shape memory alloys were fabricated by a pulse current sintering process from two types of starting powders prepared through different processes: mechanical alloying of TiH and Ni powders mixture and dehydrogenation(MA powder), and pre-mixed of Ti and Ni powders (mixed powder).
The MA powder was composed of mainly TiNi phase and a small amout of Ti2Ni and TiNi3 phases. The composition of this powder remained unchanged after the pulse current sintering at 973-1173K for 300s, while the relative density of 100% was attained for the sintering body. On the contrary, the pulse current sintering of the mixed powder at 1273K for 60-300s, led to a distinguished compositional change and the relative density of 100%. The TiNi3 phase in the sintered body could be removed on the condition of longer sintering period or by heat treatment at 1273K for 18ks; however, the Ti2Ni phase could not be removed. The composition and the thermal characteristics (Ms=318K) of these sintered bodies were found to be almost the same as those of commercially available Ti-Ni shape memory alloys.
