Mn含量对Ti_(53)Al_(45)Nb_(2)合金组织和力学性能影响

Effects of Mn Contents on Microstructure and Properties of Ti_(53)Al_(45)Nb_(2)Alloys

采用金相显微镜、X射线衍射仪、拉伸试验机、扫面电镜等手段研究了Mn含量对TiAl合金微观组织和力学性能的影响。结果表明,Ti_(53-x)Al_(45)Nb_(2)Mn_(x)(x=0、1、2.5、4,摩尔分数,%)合金的组成相包括γ-TiAl相和α_(2)-Ti_(3)Al相,添加的Mn元素以固溶原子的形式固溶于合金基体中,引起晶格畸变,导致晶面间距变大。随着x从0增至1,2.5,4,合金片层结构显著细化,片层厚度由(670±120)nm分别降到(610±90)、(580±100)和(540±90)nm。合金的室温压缩屈服强度、抗压强度和断裂应变均随着Mn含量增加先增大后减小,Ti_(51.5)Al_(45)Nb_(2)Mn_(2.5)合金性能最佳,分别达到了930 MPa、1605 MPa和30.4%。相较于未添加Mn的合金,分别提高了32.9%、35.4%和83.1%。

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 Ti_(53)Al_(45)Nb_(2)Mn_(x)(x=0、1、2.5、4,molar fraction,%)alloys are composed ofγ-TiAl andα_(2)-Ti_(3)Al 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,1605 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.