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Indexed by:期刊论文

Date of Publication:2013-11-01

Journal:INTERMETALLICS

Included Journals:SCIE、EI

Volume:42

Page Number:120-125

ISSN No.:0966-9795

Key Words:Intermetallics, miscellaneous; Phase transformation; Microstructure; Electron microprobe

Abstract:In general, the iron impurity is detrimental to the mechanical properties of Al-Si alloys. The alpha-phase and beta-phase are the most important and common iron-containing intermetallic compounds (IMCs) in Al-Si alloys. During conventional casting, the acicular beta-phase is stable, and considered to be harmful. In this paper, the Al-12%Si-2%Fe alloy was treated by power ultrasound and solidified under different cooling conditions. The effects of ultrasonic treatment (UST) and cooling rate on morphology and composition of IMCs were investigated. The results showed that UST can change the morphology and composition of iron-containing IMCs and promote the formation of metastable alpha-phase. When the ultrasound was applied at 720 degrees C, the amount of starlike alpha-phase increases and the acicular beta-phase decreases with increasing applied time of UST. In addition, the polygonal alpha-phase is formed and substitutes for the beta-phase when quenching after UST for 60 s and 120 s, suggesting that the formation of beta-phase can be suppressed under this condition. For the case of UST at 610 degrees C which the beta-phase has been nucleated, the beta-phase transforms from an acicular shape to the rod-like morphology, indicating that the cavitation-induced fracture of beta-phase. (C) 2013 Elsevier Ltd. All rights reserved.