熔体过热处理对过共晶Al-Si-Mg合金中Mg_2Si相的影响

Influence of melt superheating on Mg_2Si phase of hypereutectic Al-Si-Mg casting alloys

采用原位合成技术制备Mg2Si颗粒增强Al-18%Si-Mg复合材料,并对其进行熔体过热和Sr变质处理。研究过热温度、保温时间对Al-18%Si-Mg合金中颗粒状Mg2Si增强相的显微组织和室温力学性能的影响。结果表明:经熔体过热处理后Al-18%Si-Mg合金凝固组织得到了明显的改善,使具有树枝状或汉字状特征的Mg2Si相逐渐向十字形转变且球化趋势明显。处理工艺为过热温度860℃,保温时间25 min时,Mg2Si相均匀细小,平均尺寸由处理前的34μm减小到11.42μm,复合材料的力学性能也得到明显改善。

Mg2Si particles reinforced Al-18% Si-Mg composite material was prepared by in-situ synthesis technology,and melt superheating and Sr modification were treated on the material.Effect of superheating temperature and holding time on microstructure and mechanical properties at room temperature of Mg2Si particles reinforced phase in the Al-Si-Mg alloy was studied.The results show that the solidification structure of Al-18% Si-Mg alloy is improved significantly after melt superheating and Mg2Si phase of dendritic or Chinese characters-like shapes is changed into cross-shaped gradually and spherical particle trend obviously.When the superheating temperature is 860 ℃ and holding time is 25 min,the Mg2Si phase is uniform and fine,the average particle size is reduced to 11.42 μm compared with 34 μm when untreated and the mechanical properties of the composite materials are also improved obviously.