Effects of Mn Contents on Microstructure and Properties of Ti53Al45Nb2 Alloys
Effects of Mn content on microstructure and mechanical properties of TiAl alloy were investigated by OM,X-ray,tensile test and SEM.The results reveal that Ti53-xAl45Nb2Mnx(x=0、1、2.5、4,molar fraction,％)alloys are composed of γ-TiAl and α2-Ti3Al phases.Mn is dissolved in the alloy matrix in form of solid solution atom,inducing lattice distortion,thus leading to a larger interplanar spacing.With the increase of Mn contents,the lamellar structure is significantly refined,and the lamellar thickness is decreased from(670±120)nm to(610±90)nm,(580±100)nm and(540±90)nm,respectively.The compressive yield strength,compressive strength and fracture strain of alloys at room temperature are firstly increased and then decreased with the increase of Mn contents,which are 930 Mpa,1 605 Mpa,and 30.4％,increased by 32.9％,35.4％and 83.1％compared with those of Mn-free TiAl alloy,respec-tively,indicating desirable properties.
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