合金化对TiAl有序金属间化合物室温塑性变形的影响

Effect of Alloying on Room-Temperature Plastic Deformation of TiAl Ordered Intermetallics

研究了Ti,Mn,Cr或V的添加对TiAl有序金属间化合物室温塑性变形的影响。研究结果表明:TiAl晶体中的位错均会受到由于Ti原子周围电荷分布不对称所产生的Peierls应力深谷的限制,其自由滑移距离缩短或形成位错网络和层错偶极子等固定位错结构,这是TiAl本质脆性的根本原因。添加主要占据Al原子位置且其负电性大于Al原子的合金元素,如Ti,Mn,Cr和V,可以提高TiAl相中电荷密度分布对称性和位错可动性,从而可使TiAl的室温延性得到改善。

The effect of adding Ti, Mn, Cr or V to TiAl on its room-temperature plastic deformation has been studied. The results obtained so far indicate that the dislocations in TiAl crystal may be blocked in deep peierls stress valleys which arise from the anisotropy of charge density distributed around Ti atoms, so that their free slip lengths are shorted and the fixed dislocation structures are formed, such as dislocation networks and faulted dipoles, etc.. This is thought to be respossible for its intrinsic room-temperature brittleness. It is concluded that the alloying elements, like Ti, Mn Cr and V, which predominantly occupy Al sites in TiAl lattice and have larger values of electronegativity than Al atom, can increase the symmetry of charge density distribution and enhance the dislocation motion in TiAl. Therefore, the room-temperature ductility of TiAl can bc improved by adding these elements.