(華中科技大學 材料成形與模具技術國家重點試驗室，武漢 430074)
摘 要: 采用間接超聲振動方法制備出晶粒尺寸細小、形貌圓整的鋁合金半固態(tài)漿料，并結合可視化的示蹤粒子水模擬實驗對其制漿機理進行探討。結果表明：在容器底部對A356鋁合金熔體進行間接超聲振動處理20 s即可獲得明顯的非枝晶初晶顆粒；作用40 s后可獲得晶粒形狀系數(shù)為0.6、平均晶粒直徑為70 μm的半固態(tài)漿料；在制漿過程中，有明顯的超聲波作用的特征，即透過容器底部在熔體內部有明顯的聲流效應、空化效應以及熱效應；同時具有高頻機械振動的特征，液面攪動較大，凝結于杯壁的固相顆粒剝落，使晶核數(shù)量增加；因此，間接超聲振動作用于金屬熔體時，并不是單純的機械振動作用效果，而是超聲波和高頻機械振動的共同作用。
關鍵字: 鋁合金；半固態(tài)漿料；非枝晶組織；間接超聲振動；機理
prepared by indirect ultrasonic vibration
（National Key Laboratory of Materials Processing and Die and Mould Technology,
Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract:The process of semi-solid A356 alloy slurry prepared by indirect ultrasonic vibration (IUV) and its mechanism, combined with water simulation experiment of visual tracer particles, was investigated. The results show that the non-dendritic primary particles can be produced after A356 alloy IUV treated for 20 s at the bottom of container, and after treated for 40 s, the semi-solid slurry with grain shape coefficient of 0.6 and average grain diameter of 70 μm can be obtained. In the process of indirect ultrasonic vibration, there are obvious characteristics of ultrasonic vibration, such as acoustic streaming, cavitation and thermal effects and the high-frequency mechanical vibration characteristics, such as vigorous surface agitation, the increase of the nucleation induced by falling off solid particles formed on the crucible wall. The melt is IUV treated, the combined action of ultrasonic and high-frequency mechanical vibration are rather than single mechanical vibration effect.
Key words: aluminum alloy; semi-solid slurry; non-dendritic microstructure; indirect ultrasonic vibration; mechanism
