轧制态下Cu含量对泡沫铝泡孔结构的影响

采用液相复合-轧制技术制备不同w_○Cu的可发泡预制坯及闭孔泡沫铝材，研究了w_○Cu对泡沫铝泡孔结构的影响.结果表明:随着w_○Cu的增加，泡孔结构的均匀性增加，孔径减小，泡孔合并产生的大泡孔数量减少，但泡沫体的塌缩和老化特征增强.对比不同w_○Cu的预制坯的膨胀曲线，随着w_○Cu的增加，预制坯的最大膨胀率先增大后减小，且达到最大膨胀率的发泡时间明显减少.微观结构分析表明:在AlSi₉合金中加入Cu，生成了CuAl₂O₄和CuAl₂，CuAl₂O₄提高熔体的黏度，减小了重力排液及毛细作用的影响，提高了泡沫的稳定性.CuAl₂先于AlSi₉熔化，在晶界上形成熔池，气泡提前形核长大，使发泡过程提前完成.

Effect of Cu Content on Pore Structure of Aluminum Foams After Rolling Process

The liquid phase composite-rolling technology is used to prepare foamable preforms with different content of w_○Cu and closed-pore aluminum foams. The effect of w_○Cu on the pore structure of the aluminum foams was studied. The results show that with the increase of w_○Cu， the uniformity of the pore structure increases， and the pore size and the number of large pores produced by pore merging decrease， while the collapsing and aging characteristics of the foam are enhanced. After comparing the expansion curves of preforms with different w_○Cu， it is found that when the w_○Cu increases， _○the maximum expansion rate of the preform firstly increases and then decreases and the foaming time to reach the maximum expansion rate is greatly shortened. The microstructure analysis shows that CuAl₂O₄ and CuAl₂can be formed after adding Cu into AlSi₉ alloy. CuAl₂O₄ increases the viscosity of the melt， reduces the effect of gravity drainage and capillary action， and improves the stability of the foam. CuAl₂ melts prior to AlSi₉ alloy， forming a molten pool on the grain boundary， and the bubbles nucleate and grow in advance， so that the foaming process is completed ahead of schedule.