| Cast structures of Ti-Al alloys containing 44, 48, and 52 at.% Al, respectively, were studied after casting at different cooling rates. In 44 at.% Al alloy, slowly cooled structure consisted of fully lamellar grains of α₂and γ whereas in fast cooled one lamellar formation was considerably suppressed, so that supersaturated α₂phases with A.P.D. (Anti-Phase Domain) structures were predominantly formed. In 48 at.% Al alloy dendritic lamellar grains were the major constituent with gamma phase as interdendritic segregates. Lamellar grains became finer with faster cooling. Dendritic lamellar grains transformed from primary α were distributed within the matrix of γ in 52 at.% Al alloy. Isolated γ islands were observed inside of the lamellar grains in slowly cooled 52 at.% Al alloy. Primary phase during solidification seems to be β in 44 at.% Al alloy, while α seems to be a major primary phase in 48 at.% Al alloy. |
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