Al-25%Si合金过热处理后的凝固行为和组织研究  

Study on Solidification Behavior and Microstructure of Al-25%Si Alloy After Melt Superheating Treatment

作　　者：李艳霞[1,2] 刘俊友[1] 郭明海[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]北华航天工业学院材料系,河北廊坊065000

出　　处：《铸造》2013年第4期272-277,共6页Foundry

摘　　要：研究了熔体过热温度、冷却速度及浇注温度对Al-25%Si合金凝固形核温度、初生硅尺寸和数量分布的影响。结果显示,过热温度增加、冷却速度增大均会影响初生硅形核温度。随过热温度升高,形核温度增加,直至1 000℃过热后形核温度降低。增加冷却速度使形核温度进一步升高。不同冷却速度下,初生硅相尺寸和数量随过热温度增加以相同规律变化,1 000℃时尺寸细化达到最小值,数量达到最大值。冷却速度对初生硅尺寸的影响与过热温度有关,低过热温度下,增加冷却速度有利于初生硅相尺寸细化,过热温度升高,冷却速度对尺寸的影响逐渐减小。熔体过热处理对初生硅相的影响还与浇注温度有关,降低浇注温度,初生硅尺寸粗化,同时硅颗粒数量减少。Al-25%Si合金熔体高温过热处理后在850℃浇注,能够将初生硅相尺寸细化至30μm以下。Effects of the melt superheating temperature, cooling rate and pouring temperature on the nucleation temperature, size and quantity of primary Si phase in A1-25%Si alloy were studied. The results show that both the superheating temperature and cooling rate influence the nucleation temperature of the primary Si phase. The nucleation temperature increases with the superheating temperature rising until 1 000 ℃, after which the nucleation temperature decreases. The nucleation temperature increases with the increasing of the cooling rate further. The size and quantity of the primary Si change with the superheating temperature in the same rule when the cooling rates are different, where the size refines to the minimum value and the quantity increases to the maximum as the melt superheats to 1 000 ℃. The effect of the cooling rate on the size of primary Si depends on the superheating temperature. At the low superheating temperature, the high cooling rate promotes to refine the size, but this promotion decreases with the superheating temperature rising. The result of melt superheating influencing the primary Si is related to the pouring temperature too, and the size of primary Si coarsens and the quantity decreases with the pouring temperature decreasing. The suitable pouring temperature is 850 ℃ for Al-25%Si alloy and the size of primary Si can be refined to less than 30 μm.

关 键 词：AL-SI合金 熔体过热 冷却速度 浇注温度 平均直径 

分 类 号：TG244.3[金属学及工艺—铸造]