近共晶和过共晶铝-硅-铜合金的半固态加工

Semisolid processing of near-eutectic and hypereutectic Al-So-Cu alloys

通过添加单质硅到380铸造铝合金中，获得近共晶和过共晶铝硅铜合金的触变成形生成非枝晶的原料前，在熔体冷却至接近液相点温度5～15℃时，将它们注入永久模。这种低过热浇注（Lsc）过程使合金中很大程度上用相对较小的α-Al环取代α—Al枝晶。将LsC铸锭加工成气栓样品，在实验室于半固态加热温度568～573℃加热5mm，半固态足以使样品产生需要的球状结构，也有一些枝晶存留在起始原料中。触变成形样品经过T6热处理后硬度从84～96HB增加到121～131HB，表明它具有相当大的硬化潜在性能。％处理也改善了共晶硅的外形，对触变成形样品有潜在价值。

Experimental near - eutectic and hypereutectic AI - Si - Cu alloys obtained by adding elemental silicon to the 380 casting alloy were melted and were cooled to within 5 to 15℃ of their liquidus points before they were poured into a permanent mould in order to produce non -dendritic feedstock for thixofonning. This low superheat casting （LSC） process largely replaced α - Al dendrites with relatively smallerα - Al rosettes in all alloys. The slugs machined from the LSC ingots thus obtained were thixoformed after they were heated in situ in the semisolid range, between 568℃ and 573℃, for 5 min in a laboratory press. Semisolid soaking sufficed to produce the required globular structure even when some dendritic features were retained in the starting feedstock. The hardness of the thixoformed parts which ranged between 84HB and 96HB have increased to 121 - 131 HB after the T6 heat treatment, impl- ying a considerable age - hardening potential. The T6 treatment also improved the morphology of the eutectic silicon with potential benefits regarding the ductility of the thixaformed part.