Densification of Sintered TiAl Containing Cr by HIPing and their HIPed Microscructures.

TiAl intermetallic compounds containing Cr were prepared by sintering mixed powder compacts of TiH2. TiAl3, and Ti-55Al-15Cr(mass%) alloy. The sintered compounds produced were subjected to hot isostatic pressing (HIPing) at 1470K and 202MPa for 3.6ks without canning. The densification by Wing was examined as functions of Cr content, sintering temperature and sintered density. The microstructure of HIPed TiAl was also examined.Experimental results showed that the addition of Cr definitely influenced HlPing, and that the densification tended to be more difficult with increased Cr content. However, full densification was achieved when Cr contents were less than 4 at% for 45 at% Al alloys. HIPed density increased with increased sintering temperature, and became saturated when the relative sintered density exceeded 92%. The microstructure of HIPed Ti-45Al-3Cr(at%) alloy consisted of a and γ phases together with β phase. The amount of the β phase increased with increased Cr content and decreased Al content.