Production of TiNi sintered body by spark-plasma sintering of (Ti+Ni) powder mixture

Abstract

A powder mixture of Ti and Ni was sintered by spark-plasma sintering (SPS). Three kinds of (Ti+Ni) powder mixture were prepared with a different combination of starting materials (A, B, and C type). Sintering was carried out at 900 /spl deg/C for 5-30 min under a vacuum of 10/sup -3/ torr with an applied pressure of 50 MPa in the SPS facility. Changes in density and phase formation during the SPS process were observed. The shape memory effect was determined by DSC measurement. All three types of powder mixture showed a maximum densification rate in the temperature range of 500-600 /spl deg/C. In the early stage of sintering, powder mixture A showed a lower density compared to other mixtures. No SHS reaction was observed during the SPS process. Sintered density higher than 97% relative density was obtained from all powder mixtures. The sintered body consisted of B2 TiNi as the major phase and Ti/sub 2/Ni and TiNi/sub 3/ as minor phases. Average Ms and Af temperatures were 65 /spl deg/C and 110 /spl deg/C, respectively.