(1. 内蒙古工业大学 材料科学与工程学院，呼和浩特 010051；
2. 内蒙古新材料工程技术中心，呼和浩特 010051)
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20 min，水淬固定其半固态组织，应用Image Pro Plus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颗粒质量分数增加，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30~40 μm，更加适合于半固态触变成形。
关键字: 7075铝合金；原位TiC颗粒；二次加热；铸造
（1. School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China;
2. Centre of Technology of New Materials Engineering, Inner Mongolia, Hohhot 010051, China）
Abstract: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 TiC particles 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 30−40 μm less than that of 7075 alloy, therefore it is more suitable for thixoforming.
Key words: 7075 Al alloy; in-situ TiC particle; reheating; casting
