【摘要】 采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）研究了锻造对高铌Ti-45Al-7Nb-0.3W （at.%）合金显微组织和织构演变的影响。结果表明：铸态合金主要由平均尺寸为70μm的α₂/γ层片组织组成，而热锻态合金则呈现近双态组织（DP）。在热锻过程中，合金发生了层片结构的扭折和弯曲、变形孪晶和动态再结晶（DRX）。同时，锻造后β相中密集的位错表明，具有无序结构的高温β相有利于改善合金的热加工性。与常见的TiAl铸造织构不同，本研究中高铌TiAl铸态合金的凝固过程由于完全通过β单相区而形成了<110>γ纤维织构，即<110>γ晶向与热流方向平行。而锻态合金则表现出较强的<001>纤维织构和较弱的<302>纤维织构，这可以归因于变形孪晶。退火后，在孪晶界和孪晶交叉处发生静态再结晶，使变形织构减弱。更多还原

【Abstract】 The effect of forging on the microstructure and texture evolution of a high Nb containing Ti-45Al-7Nb-0.3W(at.%) alloy was investigated by X-ray diffractometer(XRD), scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The results show that the as-cast alloy is mainly composed of α2/γ lamellar colonies with a mean size of 70 μm, but the hot-forged pancake displays a near duplex microstructure(DP). Kinking and bending of lamellar colonies, deformation twinning and dynamic recrystallization(DRX) occur during hot forging. Meanwhile,dense dislocations in the β phase after forging suggest that the high-temperature β phase with a disordered structure is favorable for improving the hot-workability of the alloy. Unlike the common TiAl casting texture, the solidification process of the investigated as-cast alloy with high Nb content is completely via the β phase region, resulting in the formation of a <110>γ fiber texture where the <110>γ aligns parallel to the heat-flow direction. In comparison, the relatively strong <001> and weak <302> texture components in the as-forged alloy are attributed to the deformation twinning. After annealing, static recrystallization occurs at the twin boundary and intersections, which weakens the deformation texture.更多还原