摘要
在500℃下采用包套-等径角挤压(PITS-ECAP)工艺将Al-Si合金粉末颗粒固结成高致密、块体细晶材料。结果表明,PITS-ECAP工艺对粉末材料具有强烈的致密化效果。1道次PITS-ECAP后,试样整体相对密度比初始预装粉致密度提高了50%;2道次PITS-ECAP工艺变形后,合金粉末初晶硅明显细化、整体致密化强烈,C路径能高效破碎组织中粗大板片状初晶硅,使晶粒尺寸变小,圆整度提高,分布均匀,粉末材料相对密度达95%,显微硬度值增加到220 HV25,初晶硅形状系数为0.64,致密化及初晶硅细晶化效果最好;A路径虽致密效果不好但有利于等温处理后的初晶硅细晶化,Bc路径产生的初晶硅细晶化、致密化效果较差。在PITS-ECAP工艺变形过程中,剧烈塑性剪切变形、较高静水压力和有效应变积累是合金粉末致密化、初晶硅细晶化的主要驱动因素。
The densification behavior of equal channel angular pressing for Al-Si2O alloy powders in capsule was studied. Al-Si2O alloy powder particles were successfully consolidated into full dense bulk material with fine grains at 500 ℃ by the powders in capsule-equal channel angular pressing （PITS-ECAP）. The results show that PITS-ECAP process has a strong densification effect on the powder material, and the relative density of the sample as a whole is creased by 50% compared to the initial pre-powder density under the first PITS-ECAP process; After 2 passes of PITS-ECAP, there exists obvious refinement for early crystal silicon alloy powders and the overall strong densification for Al-Si2O alloy powder. Primary Si in Al-Si2O alloy powders are refined to spherical shape and crystal dimension is diminished, and the round and homogeneous grains are obtained; and overall relative density is 95%, the microhardness is 220 HV25, and average particle shape factor is about 0.64 via route C process, so route C is the best one for densification and grain refinement of primary silicon. Route A is not good to densification behavior but in favor of grain refinement of primary silicon isothermal treatment after 2 passes of PITS-ECAP, and route Bc process is inefficient for the densification and grain refinement of primary silicon, too. It is also indicated that the severe plastic shear deformation, high hydrostatic pressure and the cumulation effective strain ensure a high density and a fine microstructure of powder consolidate.
出处
《粉末冶金材料科学与工程》
EI
北大核心
2015年第3期331-337,共7页
Materials Science and Engineering of Powder Metallurgy
基金
江西省自然科学基金资助项目(20151BAB206040)
江西省教育厅科技项目(14722)
华中科大模具国家重点实验室开放基金项目(P2014-19)
