| The purpose of this study is to investigate the effect of composition on the microstructure and mechanical properties of TiAl alloys. The composition ranges studied were Ti-xAl(x=43.7, 45.6, 47)-yMn(y=0.3). The mechanical properties have been characterized and correlated with microstructure, tetragonality, and deformation behavior. Two phase (α₂+γ) alloys have single γ grains and lamellar grains, which consist of twin-related L1。γ Phase and α₂phase. Addition of Mn promotes the formation of twin-related structure and the refinement of lameller structure and grain size. Increase in Ti/Al ratio promotes the refinement of grain size, but increases lamellar spacing. The modification of microstructure directly influences the compression properties and deformation mode of TiAl alloys. It has been found that Mn addition and increase of Ti/Al ratio enhance the plasticity of two phase (α₂+γ) alloys. The ductilization effect of Mn is partly due to its ability to promote the formation of deformation twins and dislocation generation at the twin intersections. |
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