挤压温度对γ-TiAl基合金组织与性能均匀性的影响

Influence of Extrusion Temperature on the Microstructure and Tensile Properties Homogeneity ofγ-TiAl Based Alloys

研究了挤压温度对TiAl合金变形组织与性能均匀性的影响。结果表明,TiAl合金挤压件芯部与边缘组织差异明显,芯部为粗大的近片层组织,边缘为细小的等轴近γ组织,这与变形温度和变形量分布不均匀有关。随着挤压温度升高,芯部残余片层晶粒减少,而再结晶片层晶粒增多。变形组织中等轴γ晶粒体积分数越多,片层晶粒尺寸越小,最终热处理态合金晶粒尺寸越小,室温伸长率越高。1280℃挤压棒材热处理组织较均匀,芯部与边缘室温伸长率差别较小。

γ-TiAl based alloys were canned extruded in theα+γphase field at near isothermal condition.The effects of extrusion temperature on the homogeneity of deformed microstructures and subsequentlyαsolid solution treated microstructures in the whole extruded rod were investigated,and room temperature tensile properties of corresponding microstructures were compared.The results reveal that the deformed microstructures in the center and edge of rod are different.The center region presents coarse near-lamellar structure,while the edge region has fine equiaxed near-γphase,which are related with the deformed temperature and inhomogeneity of deformed rate distribution.With the increase of the extruding temperature,the residual lamellar grain in the center region is decreased with the increase of recrystallized lamellar grain.With the equiaxedγphase increasing in the deformed structure,the grain size of the lamellar structure is refined gradually,so the grain size in the alloy after solid solution is decreased,leading to the improvement of the elongation.The extruded rod at 1280℃has the homogeneous structure after solid solution,and the elongation of the alloy presents the ingronat difference in the center and edge at room temperature.