超声振动功率对AZ31B镁合金铸锭凝固组织的影响  

Effects of Ultrasonic Power on Solidification Structure in AZ31B Alloy Ingots

作　　者：毕秋[1] 李克[1] 高挺[1] 郭峰[1] 

机构地区：[1]南昌大学机电工程学院

出　　处：《特种铸造及有色合金》2009年第6期576-579,共4页Special Casting & Nonferrous Alloys

基　　金：江西省自然科学基金资助项目(0650090);江西省科技攻关项目(S0006)

摘　　要：采用熔体超声处理及底部水冷工艺,在不同功率参数条件下制备了AZ31B镁合金铸锭,用定量金相系统测定和比较凝固组织中初生α-Mg相的晶粒尺寸。结果表明,随着超声功率的增加,声空化的形核作用增强,晶核数量增多。同时,声流速度加快,对结晶潜热和二次枝晶臂根部溶质的扩散、破碎枝晶的分散作用更强,α-Mg相形态由枝晶状向蔷薇状和球状转变。超声功率为600W时,对α-Mg初生相的细化效果最佳,晶粒平均尺寸细化到93μm。当功率升高到800W时,由于热效应超过了对流散热作用,晶粒又变得粗化。AZ31B alloy ingots were prepared by applying ultrasonic vibration on the top of the melt with different powers and water-cooling at the bottom of the stainless steel crucible.Quantitative metallographical analysis software was employed to calculate the grain size of primary α-Mg phase in the solidification structure.The results reveal that with increasing in ultrasonic powers,the nucleus numbers are increased as a result of the enhancement of cavitation-induced nucleation.Meanwhile,with accelerating in acoustic streaming,the diffusion of the latent heat and the solute at the roots of secondary dendrite arm and the dispersion of dendrite-broken are improved,which is responsible for the transformation of α-Mg phase from dendrite into rosette and granular structure.With applying ultrasonic power of 600W,the average grain size of the α-Mg phase can be dropped to 93μm,while it becomes coarse with 800W power because of the heating effects of ultrasonic more than the dissipation of the latent heat.

关 键 词：镁合金 超声振动 晶粒细化 

分 类 号：TG292[金属学及工艺—铸造]