Titanium silicide reinforced in situ synthesized TiAl composites and their mechanical properties

A processing route involving in situ development of reinforcements of titanium silicides in a series of TiAl-based matrices has been attempted. The main features of this processing route are: 1) mechanical alloying of 58Ti-21Al-21Si (at%) powder mixture for 20-h to form a predominantly Ti solid solution; 2) incorporating a small quantity of mechanically alloyed powders, referred to as precursors, into Ti-Al-X (X stands for Cr, Mn, Nb, or their combination) powder mixtures that act as the matrix; and 3) hot isostatic pressing (HIPing) of the cold compacted mixture at a temperature of 1100°C for 4-h. In the present study, a series of composites based on different Ti-Al-X matrices were synthesized. After annealing at 1150°C for 4-h, their microstructures and mechanical properties were characterized by scanning electron microscopy (SEM) and compression tests at room and elevated temperatures (600°C and 800°C). The influence of alloying elements in the matrix was evaluated from the stress-strain response curves.