The Formation Mechanism and the Microstructure of Ti-Al Intermetallic Compound System Composite Materials Fabricated by Spark Plasma-combustion synthesis Method

Abstract

The aims of this study were to observe the microstructure and the tormed phases of Ti-Al intermetallic compound system composites made by spark plasma-combustion synthesis and to investigate the phase formation mechanism.
During the spark plasma sintering of the Ti:Al=1:1 powders, combustion synthesis was indicated by the abruptly shringkage in sample volume at Al melting point. The microstructure and the formed phase of spark plasma-combustion synthesized composites varied according to Ti particle size. For example, TiAl₃ phases were formed when 100μm Ti powders were used, and TiAl, Ti₂Al and Ti₃Al phases were formed when 10μm Ti powders were used (the sintering temperature was 973K). The formation mechanism of compounds using spark plasma sintering has two processes; combustion synthesis at Al melting point and diffusion in the high temperature region.