通过在Al?0.4Zr合金凝固过程中外加超声场研究超声处理对Al3Zr金属间化合物形成的影响.超声处理分别采用在凝固过程中的3个温度区间:830~790℃(高于液相线)、790~750℃(横跨液相线)和750~710℃(低于液相线).超声处理后利用扫描电子显微镜对铸态合金中生成的Al3Zr金属间化合物的尺寸和形貌进行分析观测.结果显示,超声处理后Al3Zr金属间化合物的尺寸显著减小而且形貌也从流星镖状转变成细小片状.讨论Al3Zr金属间化合物超声细化机理.结果表明,超声处理高于液相线时形成的细化效果主要是由于空化气泡激发氧化铝颗粒成为Al3Zr金属间化合物形核质点从而提高形核率;超声处理低于液相线时形成的细化效果主要是由于空化气泡打断生长中的Al3Zr金属间化合物.
The effect of ultrasonic treatment on the formation of primary Al3Zr was investigated by applying ultrasound to an Al?0.4Zr alloy. Three temperature ranges were selected, i.e., 830 to 790 ℃ (above liquidus), 790 to 750 ℃ (cross liquidus) and 750 to 710 ℃ (below liquidus) for ultrasonication. Using the scanning electron microscopy, both the size and morphology of the primary Al3Zr particles were examined. It was found that the size was significantly reduced and the morphology changed from large throwing-star shape to small compact tablet shape. The mechanisms for refinement of primary Al3Zr were discussed. It is suggested that sonocrystallization theory via activation of aluminium oxide particles is responsible for the refinement of primary Al3Zr when ultrasonic melt treatment (UST) is applied within the fully liquid state. The refinement of primary Al3Zr particles when UST is applied in the slurry (growth stage) is due to the sonofragmentation.
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