铝合金半固态浆料中球形颗粒的演变(英文)

Evolution of globular microstructures during processing of aluminium slurries

用AlSi7Mg0.6半固态浆料进行实验,研究球形颗粒的演变机理。在略高于液相线温度下水淬的样品中结晶相主要为枝晶,而采用旋转圆筒的方式来搅拌熔体使其冷却到半固态温度范围内时样品的结晶相完全球化。在铸造前进行较长时间的内冷却和搅拌,可以得到较高的固相分数。不同大小的枝晶碎片的存在表明,在搅拌过程中,初始的固相分数形成后不再受冷却的影响。

Slurry processing experiments were performed with AlSi7Mg0.6 to identify the globularization mechanisms.The melt sample water quenched slightly above the liquidus point is predominantly dendritic while that cooled into the semi-solid temperature range internally via stirring the melt with a rotating cylindrical block of the alloy itself becomes fully globular.The globules are much smaller when internal cooling and stirring are employed longer to achieve higher solid fractions before casting.Coarse dendrite fragments of various sizes are revealed,in the case of stirring after an initial fraction of solid is first formed without the benefit of additional internal cooling.