准共晶铝硅合金半固态坯料重熔加热时的组织演变

Microstructure Evolution of Semi-solid Billet of Quasi-eutectic Al-Si Alloys during Reheating

以Al-10Si-3Cu-1Mg准共晶铝硅合金为研究对象,采用低温铸造法制得半固态淬火坯料,研究坯料重熔加热温度和保温时间对组织演变的影响。结果表明,提高加热温度或者延长保温时间,可使准共晶铝硅合金中共晶硅由铸态坯料显微组织的条状、蠕虫状及网状转变为球状或块状,网状被打开直至长成粗大的球状;共晶α相与初生-αAl相合并、长大成完全的非枝晶组织。准共晶铝硅合金坯料半固态加热重熔的最佳工艺参数为:558℃保温40 min或568℃保温20 min,既可使初生-αAl相完全非枝晶化,又可使共晶硅转变为小的粒状。

Semi-solid billets were prepared by using low-temperature casting with Al-10Si-3Cu-1Mg quasi-eutectic Al-Si alloy. Effects of holding time and heating temperature on the evolution of microstructures of the billets were studied. The results show that increasing the heating temperature or the holding time can make eutectic Si phase changes from strip or vermicule or network structures in to small nodules, and even then to be the large spheres. The primary a-Al phase consolidates with eutectic a-Al phase grows into complete non-dendrite structure. The best technical parameters of remelting are 558℃ and 40 rain for holding time or 568 ℃ and 20 min. Under these conditions, primary a-Al phase can grow into complete non-dendrite microstructure and eutectic Si phase granular into small nodules.