原位颗粒含量对半固态7075铝合金组织的影响  

Effect of the Volume Fraction of In-Situ TiC Particles on the Semi-Solid Micro- structure of Spray Formed 7075 Al Alloy

作　　者：刘慧敏[1] 呼努斯图[2] 崔华[1] 杨滨[1] 张济山[1] 

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083 [2]内蒙古大学理工学院,呼和浩特010022

出　　处：《北京科技大学学报》2004年第1期59-62,共4页Journal of University of Science and Technology Beijing

基　　金：国家自然科学基金资助项目(No.50171010)

摘　　要：制备具有不同原位Tic颗粒含量的喷射沉积7075铝合金,在610℃和620℃进行二次加热并保温30min,淬火固定半固态组织.采用扫描电镜观察其组织,利用平均截线法统计其晶粒尺寸,分析不同颗粒含量对喷射沉积7075铝合金半固态组织的影响规律.结果表明:当TiC颗粒含量达到2.91％(体积分数)时已经产生良好的钉扎效果,使得合金基本保持喷射沉积组织特征,能够满足后续的半固态成形工艺要求;TiC颗粒含量超过2.91％后,晶粒尺寸会进一步减小,但晶界上的颗粒明显增多并呈网状分布;TiC颗粒含量小于2.91％时,局部区域发生晶粒的异常长大现象,使合金组织的均匀化程度下降.The microstructure of in-situ reactive spray formed 7075+XTiC (the volume fraction X=0,1.15%, 1.73%, 2.91%, 4.48%, 5.95%) after heat treatment at 610℃ and 620℃ for 30min were observed using SEM. The grain size was measured by a mean linear intercept method to analyze the effect of different volume fractions of in-situ TiC particles on the semi-solid microstrucrure of spray formed 7075 alloy. It was shown that at 610℃ the pinning effect was significant when the volume fraction of in-situ TiC particles was up to 2.91%, which made micro-structures of the alloy keep as-spray formed characteristics and could meet the requirement of subsequent semi-solid processing. If that of in-situ TiC particles exceeded 2.91%, the grain size was further decreased, but the number of dispersoids and particles at grain boundaries evidently increased with net-shaped distribution. When that was less than 2.91%, the grain grew abnormally at local areas, resulting in the homogenization reduction of grain structure.

关 键 词：原位颗粒含量 喷射沉积 7075铝合金 半固态组织 碳化钛 合金组织 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG113.12[金属学及工艺—金属材料]