Influence of Ultrasonic Treatment on the Microstructure of Hypereutectic Al-17 Wt%Si Alloys

Abstract

The effect of ultrasonic melt treatment (UST) on the microstructure of hypereutectic Al-17 wt.% Si alloys was investigated. UST applied to a melt at a temperature range of 750 - 800 °C refines the primary Si dramatically but has little influence on the grain size of primary Al. The solidification behaviour was characterised by thermal analysis and a mechanism responsible for the primary Si refinement was suggested. Whilst UST has no effect on the grain refinement, a significant increase in the matrix hardness as well as the tensile strength in the as cast condition is possibly associated with solid solution hardening. Detailed microstructure analysis was carried out and characteristics of the intermetallic formation in the Al-17 wt.% Si alloys were further discussed in the view point of Cu solubility in the Al matrix, which is considered to increase with UST.

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“…В роботі [43], де досліджено вплив ультразвуку практично на такий же стоп Al-18,5Si-4Cu, повідомляється, що оброблення розтопу в діяпазоні температур 750-800°C значно поліпшує якість первинного Si, але мало впливає на розмір зерна первинного Al. Передбачається, значне збільшення твердости матриці, а також міцности на розрив литого матеріялу пов'язано зі зміцненням твердого розчину.…”

Refinement of Microstructures for Aluminum Piston through Ultrasonic Melt Treatment

“…한편, 초음파처리한 피스톤에서는 냉각속도가 서로 다른 A, B, C, D 부위에서 초정 Si의 크기가 21.1~23.1 μm으로 비 슷하였는데, 이는 냉각속도가 느려짐에 따라 감소한 용탕의 과냉도가 초음파처리에 의해 충분히 보상되었기 때문으로 생 각된다 [11,12,14]. 초정 Si의 원모양정도는 초음파처리에 의해 약 0.3에서 약 0.4로 증가하였는데 (Fig.…”