闭孔泡沫Mg_2Si/Al复合材料的制备及压缩性能研究

Fabrication and Compression Properties Investigation of Closed-cell Mg_2Si/Al Composite Foams

采用熔体发泡法,以原位自生Mg2Si/Al复合材料为基体,CaCO3作发泡剂,通过控制温度和搅拌参数,成功制备出不同密度的闭孔泡沫铝。通过静态压缩性能试验发现:泡沫Mg2Si/Al复合材料的压缩过程具备泡沫金属压缩变形的三阶段(弹性变形、应力平台区、致密化阶段)特征;压缩屈服强度和平台应力均随密度增加而增大;屈服点附近应力值下降,应力平台区出现锯齿波形,暴露出孔壁的脆性破裂特征。经过人工时效热处理,泡沫Mg2Si/Al复合材料的屈服强度显著增大。通过观察孔壁的微观组织发现,Al基体被孔壁中粗大的Al+Mg2Si伪共晶组织所割裂。

Closed-cell aluminum foam specimens with different densities were fabricated successfully by direct foaming of melt controlling temperature and stirring parameters, using in-situ g2Si/Al composite as matrix and CaCO2 as blowing agent. The results of quasi-static compression test of specimens showed that, quasi-static compres- sion of g2Si/Al composite foam possesses typical three-stage characteristic of metal foam compression; compression yield strength and plateau stress of specimens increased with their densities increasing;the decrease of stress near the yiel-ding point and serrations in stress plateau expose brittle-rupture characteristic of cell walls. Through artificial age- ing heat-treatment, compression yield strength of g2Si/Al composite foam increased remarkably. It was found that ductile Al matrix was rent by the thick pseudo-eutectic Al±Mg2Si, through observation of microstructure of cell walls.