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由固体和分子经验电子理论 (EET)分析了Ti-Al系金属间化合物合金化前后的价电子结构 ,再计算了该系合金各相的均匀变形因子α和解理能Gc 值 ,据此分析了合金化对该系金属间化合物脆性的影响。结果表明 ,常量合金化元素Nb使Ti3Al基合金的α2 相无序化 ,增加了韧的第二相 ,减弱了Ti-Ti共价键 ,综合导致α和Gc 值增大 ,使Ti3Al的脆性有本质改善 ;微量合金化元素Mn减弱了TiAl基合金的Al-Al共价键 ,并诱发孪生 ,使α和Gc 有所提高 ,在一定程度上降低了TiAl的脆性 ;TiAl3极低的α和Gc导致恶劣的本征脆性 ,Mn也难以改变其脆性本质
The valence electron structures of Ti-Al intermetallic compounds before and after alloying were analyzed by solid and molecular empirical electron theory (EET), and then the uniform deformation factor α and the cleavage energy Gc of each phase of the alloy were calculated. Effect of alloying on the brittleness of the intermetallics. The results show that the constant alloying element Nb disordered the α2 phase of the Ti3Al-based alloy, increased the ductile second phase and weakened the Ti-Ti covalent bond, which resulted in the increase of α and Gc values and the brittleness of Ti3Al The results show that the microstructure of the TiAl3 alloy decreases with the increase of the content of Mn and the intrinsic properties of the TiAl3 alloy. The microalloying of the Mn reduces the Al-Al covalent bond of the TiAl-based alloy and induces twinning, which leads to the increase of α and Gc and to a certain extent, Resulting in poor intrinsic brittleness, Mn is also difficult to change its brittle nature