熔体超声波处理对Al-5%Si铸锭凝固组织的影响

Effect of ultrasonic melts treatment on solidified structure of Al-5%Si alloy

为了研究超声波对金属熔体凝固过程中的影响,使用Al-5%Si合金进行了实验。在实验中采用几种不同的方法处理金属熔体:不添加除气剂、只添加除气剂、既添加除气剂又进行超声波处理。利用克劳修斯-克拉柏龙方程分析了超声波细化金属铸锭凝固组织的机理。结果表明,除气剂的添加与否对Al-5%Si合金铸锭组织的细化没有影响,铸锭由粗大的柱状晶组织构成;采用合适的超声波处理时间,Al-5%Si合金铸锭的等轴晶获得率大幅度提高,可使整个铸锭组织变为细化的等轴晶组织;超声波振动时间过长将导致铸锭内气孔的增加;根据克劳修斯-克拉柏龙方程,某一强度的超声波引起的压力冲击波作用,导致液相转变为固相,引起了超声波的细晶作用。

A series of experiments were conducted to investigate the effect of ultrasonic on solidification of molten Al-5%Si alloy. The several different means that is without degasser, with degasser only, with degasser and ultrasonic treatment was adopted in experiment. In addition, the grain refinement mechanism of ultrasonic into molten metal ingot was analyzed by using the Clausious-Clapyron Equation. The results show that the effect of addition or no-addition of degasser on grain refinement of Al-5%Si alloy ingot is making no difference, and the ingot consists of coarse columnar structure. By ultrasonic treatment with optimum treatment time, the equiaxed grain obtaining rate Al-5%Si alloy ingot is increased obviously, and the bulk of the ingot can be fine equiaxed structure. Excessive ultrasonic vibration will result in increasing of porosity in the ingot interior. Clausious-Clapyron Equation indicates that the effect of the pressure waves induced by ultrasonics of this intensity causes a phase change of liquid to solid due to the increase of melting point.