通过对片层取向与单轴应力方向呈不同角度的Ti－45Al－8Nb (原子分数, %)合金多孪晶合成(PST)晶体进行压缩实验, 获得了室温压缩性能,分析了断口形貌及断裂失效的原因, 并对Nb的强化作用进行了分析.PST晶体片层取向平行或垂直于应力方向时, 剪切变形沿垂直于片层界面的方向前进;而当片层取向与生长方向夹角为45°时, 剪切变形沿平行于片层界面的方向前进.0°取向PST晶体屈服强度最高, 可达1296 MPa; 45°取向PST晶体塑性最好,压缩塑性应变约为1.1%, 但屈服强度最低仅为847 MPa. Nb可以细化片层组织,提高位错运动的分切应力并降低层错能, 使室温屈服强度显著提高.

Room temperature compression performance of polysynthetic twinned crystal (PST crystal) in Ti－45Al－8Nb (atomic fraction, %) alloys with different angles between lamellar orientation and uniaxial stress direction was studied. The causes of the fracture failure were investigated by the fracture surface and the effects of the Nb element on strengthening were also studied. It was found that when the lamellar orientation in the PST crystal was paralleled or vertical to the stress direction, shear deformation was vertical to lamellar interface, and when the angle of lamellar orientation to the stress direction was 45°, the shear deformation was paralleled to lamellar interface. The yield strength of the 0° PST crystal was the maximum which was up to 1296 MPa. The PST crystal of 45° had the best compression plastic strain of approximately 1.1%, but its yield strength was the minimum of only 847 MPa. Nb element could refine lamellar structure and improve the room temperature yield strength significantly through increasing shear stress of dislocation motion and reducing the stacking fault energy.