采用无保护和有保护套管两种结构的超声不锈钢工具头,在相同实验条件下作用于Al-5%Si合金熔体,研究了功率超声对其凝固过程的细化机理。结果表明,经功率超声后晶粒均得到细化,但细化效果有差异,其原因在于功率超声对晶粒的细化作用有空化效应和声流效应,此外,工具头中Fe原子进入熔体对晶粒细化起到异质形核作用。 The stainless steel tool head with no protection and protective sleeve structure was used to melt the Al-5% Si alloy under the same experimental conditions. The refining mechanism of the ultrasonic solidification process was studied. The results show that the grains after ultrasonic powering are refined, but the refining effect is different because of the cavitation effect and sound flow effect of the power ultrasound on the grain refinement. In addition, Fe atoms in the tool head enter Melt grain refinement play a heterogeneous nucleation role.