中文摘要：

采用原位反应近液相线铸造法制备具有不同原位TiC颗粒含量的TiCp／7075铝基复合材料，在7075铝合金固-液两相区间（477～635℃）的580和600℃进行二次加热并保温20min，水淬固定其半固态组织，应用ImageProPlus软件测量平均晶粒尺寸及形状因子，研究原位TiC颗粒含量对该合金二次加热组织的影响。结果表明：当原位TiC颗粒质量分数为0～4．4％时，随着原位TiC颗粒质最分数增加，合金铸态组织直接转变为等轴晶组织，且在二次加热过程中，原位TiC颗粒对晶粒的长大行为具有明显的抑制作用：在相同的二次加热条件下，4．4％TiCp/7075铝基复合材料的平均晶粒尺寸比7075基体合金的减少30-40μm，更加适合于半固态触变成形。

英文摘要：

The TiCp/7075 Al matrix composites with different TiC particles contents were prepared by in-situ reactive near-liquidus casting, the sectioned specimens were reheated isothermally at 580 and 600℃ for 20 min in the two-phase （liquid＋solid） region （477-635℃） of the near-liquidus casting 7075 alloy, then quenched in water. The grain size was measured by Image Pro Plus and the effect of in-situ TiCparticles on the reheating structure was analyzed. The result shows that when the content of TiC particles is 0-4.4% （mass fraction）, the in-situ TiC particles can not only keep near-liquidus casting 7075 alloy with finer and globular microstructure, but also control the grain growth evidently during reheating under the same condition. The average grain size of 4.4%TiCp/7075 Al matrix composites is 30-40μm less than that of 7075 alloy, therefore it is more suitable for thixoforming.