Pulsed current sintering of mechanically alloyed Ni-Ti powder

In order to fabricate the compacts with complicated shape, Ni-Ti powders we re synthesized by mechanical alloying(MA) and consolidated by pulsed curren t sintering. Ni-50 at%Ti powders were synthesized by MA of pure elemental Ni and Ti powd ers using a planetary ball milling for 180 ks, 360 ks and 540 ks. The X-ray diffraction profile of the obtained MA powders contained a broad peak. MA powders milled for 180 ks and 360 ks consisted of fine Ni and Ti grains and melted at about 1150 K by self-propagating high-temperature synthesis (SHS ) during pulsed current sintering. The MA powder milled for 540 ks containe d a large amount of Fe. This is because NiTi phase was produced by SHS duri ng the MA process. The addition of 2 at%B to the starting powders of the MA was prevented a SH S reaction during pulsed current sintering. Ni-49 at%Ti-2 at%B powders synt hesized by MA were consolidated to compacts with complicated shapes by puls ed current sintering. The obtained compacts consisted of NiTi, Ti2Ni, Ni3Ti and TiB2 phases. The result of differential scanning calorimetry measureme nt for the compacts heat-treated at 673 K for 3.6 ks suggested that those p ossessed shape memory effects.