Structure and Mechanical Properties of the Hot Pressed Compact of Ti-rich TiAl Powder Produced by the Plasma Rotating Electrode Process.

Abstract

The structure and the compressive mechanical properties of the Ti-rich TiAl (approximately Ti-47at"/oAl) compact produced by vaccum hot pressing of PREPed powder were investigated and comparedwith those of the compact having approximately stoichiometric TiAl composition (Stoi-TiAl compact) in the previous study. Ti-rich TiAl compactshowedu Itra-fine microduplex structure (average grain diameter, 2 um)consisting of equiaxed y grain and the grain which was composed of (y+0e2) Iamellar structure. Such a Ti-rich TiAl compact indicated higher strength and better ductility than those of the Stoi-TiAl compact at room temperature. However, at high-temperature such as 1 223 K, flow stress of the Ti-rich TiAl was iower than that of the Stoi-TiAl compact. During the deformation of the Ti-rich TiAl compact at 1 223 K, dynamic recrystallization (DR) which introduced a certain extent of grain refinement was occurred. This compact exhibited larger m value than 0,3 at 1 223 K, and was presumedto be deformed by superplastic flow closely related to DR,