铸造2012，Vol.61Issue(4)：425-430,6.
超声熔体处理Al-7％Si合金坯料的半固态铸造
Semisolid Casting with Ultrasonically Melt-Treated Billets of Al-7％Si Alloys
摘要
Abstract
The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-like iron compounds of β-Al5-feSi turn into harmless from without the need for applying refining additives or expensive virgin ingots. The microstructural modification of Al-7mass% Si alloy billets with different iron contents was examined by applying ultrasonic vibration during the solidification. Ultrasonically melt-treated billets were thixocast right after induction heating up to the semisolid temperature of 583 ℃, the microstructure and tensile properties were evaluated in the thixocast components. Globular primary α-Al is required to fill up a thin cavity in thixocasting, so that the microstructural modification by ultrasonic melt-treatment was firstly confirmed in the billets. With ultrasonic melt-treatment in temperature range of 630 ℃ to 605 ℃, the primary α-Al transforms itself from dendrite into fine globular in morphology. The coarse plate-like β-Al5FeSi compound become markedly finer compared with those in non-treated billets. Semisolid soaking up to 583 ℃ , does not appreciably affect in size of β-Al5FeSi compounds; however, it affects the solid primary α-Al morphology to be more globular, which is convenient for thixocasting. After thixocasting with preheated billets, eutectic silicon plates are extremely refined due to the rapid solidification arising from low casting temperature. The tensile strength of thixocast samples with different iron contents does not change much even at 2mass% of iron, when thixocast with ultrasonically melt-treated billets. However, thixocast Al-7mass% Si-2mass% Fe alloy with non-treated billets exhibits an inferior strength of 80 MPa, compared with 180 MPa with ultrasonically melt-treated billets. The elongation is also improved by about a factor of two in thixocastings with ultrasonically melt-treated billets for all iron contents of Al-7mass%Si alloys, for example, the elongation of 1 l%in thixocast of Al-7mass%Si-0.5mass% Fe alloy with ultrasonically melt-treated billets, 5% in that with non-treated billets.关键词
铸造Al-Si合金/超声辐射/触变铸造/α-Al/含铁化合物Key words
cast Al-Si alloy/ ultrasonic radiation/ thixocasting/ α-aluminum/ iron compound分类
矿业与冶金引用本文复制引用
Yoshiki Tsunekawa,Masahiro Okumiya,Takahiro Motomura..超声熔体处理Al-7％Si合金坯料的半固态铸造[J].铸造,2012,61(4):425-430,6.基金项目
感谢日本文部科学省科研基金(23560898)对本研究的财政资助. （23560898）
