(华中科技大学 材料成形及模具技术国家重点实验室，武汉 430074)
摘 要: 研究超声振动制备过共晶Al-Si合金半固态浆料中工艺参数对半固态浆料组织的影响规律。利用A390铝合金熔体，超声振动至液固相线温度区内制浆，研究超声振动时间、振动后保温及空振比等不同条件下半固态浆料的组织变化。结果表明：超声振动后初晶Si可细化到20 µm左右；浆料在保温过程中，初晶Si粒以8 µm/min的平均速度快速长大，2 min内初生Si晶粒仍保持较好的圆整度；2 min后初生Si晶粒慢慢恶化；在1℃/min的冷却速度下，在0.5~10 min的振动时间范围内，初生Si以小于2.5 µm/min的速度缓慢长大；当超声振动的空振比为0.5时，初生晶粒的细化效果最好。
关键字: Al-Si合金；超声振动；过共晶；半固态浆料；空振比
（State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract:The effects of process parameters on microstructures of hypereutectic Al-Si semi-solid slurry were investigated. The A390 melt was imposed with ultrasonic vibration once it was poured into the metal cup and controlled in the liquid-solid temperature range, and the effects of ultrasonic vibration time, isothermal holding time, rest-work ratio on the semisolid slurry were studied. The results show that the primary Si phase is refined to about 20 µm. And with the increase of the isothermal holding time after ultrasonic vibration period, the primary Si particles grow up rapidly at the velocity of 8 µm/min, and the primary Si particles remain globular in 2 min while the morphologies deteriorate after 2 min. The primary Si particles grow slowly at the speed below 2.5 µm/min with relative stable morphology under ultrasonic vibration within 0.5−10 min. Ultrasonic vibration with rest-work ratio of 0.5 other than continuous ultrasonic vibration achieves the best refinement result.
Key words: Al-Si alloy; ultrasonic vibration; hypereutectic; semisolid slurry; rest-work ratio
