Abstract
Effect of phase change from unstable to stable phase on densification process by pressure sintering was studied using mechanically alloyed powder. Powder mixture of Ti and Si having the composition of Ti-37.5mol%Si were milled for 3600ks. The powder showed homogeneous microstructure and amorphous-like XRD profile. Milled powder was vacuum hot pressed at the heating rates of 5, 10 15, 20K/min up to 1273K with applying constant pressure of lOOMPa, then kept for 10.8ks. It was observed that the sudden increase in density at the temperature range between 840K and 905K. This temperature range showed good agreement with that of the phase formation from amorphous to stable phase, Ti_5Si_3. It was observed that the compact under a lower heating rate exhibited higher density and densification rate at the temperature over about 950K. It is concluded that the fine grain superplastic deformation acts an important roll in densification of MA powder having amorphous-like structure.
