TiC颗粒对半固态铝合金晶粒长大行为的影响

Effect of TiC particle on grain growth of Al alloy in the semi-solid state

采用原位反应液相线铸造方法制备含有2.5%(体积分数)原位TiC颗粒的7075铝合金,在其固液两相区进行二次加热保温实验,淬火固定其半固态组织后,通过扫描电镜观察合金的晶粒长大规律,研究原位颗粒对晶粒长大行为的影响。结果表明,原位TiC颗粒不仅使合金铸态组织直接变为等轴晶组织,而且在合金的二次加热过程中对晶粒长大行为具有抑制作用,在600℃保温5、10和30min的相同条件下,TiCp/7075铝基复合材料晶粒尺寸比7075基体铝合金的减小30-40μm。

The microstructure of in-situ reactive liquidus cast 7075 + 2.5 vol% TiC Al alloy in the semi-solid state were observed using SEM. The grain sizes were measured using a mean linear intercept method and the effect of in-situ formed TiC particles on grain growth in the two-phase (liquid + solid) region of liquidus cast 7075 Al alloy were analyzed. The results show that the in-situ formed TiC particles can not only make the liquidus cast 7075 Al alloy with fine and equiaxed grains but also control evidently grain growth during reheating of the alloy. The average grain sizes of 7075 + 2.5 vol% TiC Al alloy decrease 30-40 μm compared to 7075 Al alloy when the alloys are reheated at 600°C for 5, 10, 30 min.