纯钼粉末包套等径角挤压致密化行为  

Densification behavior of equal channel angular pressing for pure Mo powder in capsule

作　　者：李永志[1] 于福义[1] 白小波[1] 

机构地区：[1]九江学院机械与材料工程学院,九江332005

出　　处：《粉末冶金材料科学与工程》2013年第4期594-598,共5页Materials Science and Engineering of Powder Metallurgy

基　　金：江西省十二五重点学科"材料加工工程"资助项目;2011质量工程"教学团队"项目

摘　　要：在500℃等温条件下采用包套等径角挤压(PITS ECAP)工艺将纯钼粉末颗粒直接固结成高致密、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使粉末之间发生颗粒重排、弹塑性变形等行为,材料头部区域和尾部区域的致密情况较差,试样整体相对密度约为87%,比初始预装粉致密度提高了33.85%;经过2道次C路径ECAP变形后,试样X、Y面均受到剧烈剪切作用,促使颗粒破碎、熔融、细化,近圆形孔隙被挤扁、焊合,组织均匀,试样的各变形区域的致密化进程加快,整体相对密度达96%,且主变形区域相对密度为99%,近全致密;同时显微硬度提高了137.93%。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粉末材料致密化的主要动驱因素。The densification behavior of equal channel angular pressing for pure Mo powders in capsule was studied. Pure Mo 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 powder particle rearranges, elastic and plastic deformation are happened under the first PITS-ECAP process; the densification process is slower and dense condition is the worst of the head zone and tail zone, the relative density of the sample as a whole is about 87%, increased by about 33.85% more than the initial sample. After 2 passes of PITS-ECAP via route C, microstructures at X, Y planes of each sample are all severely sheared and elongated along a certain direction with fine banded structures; the grains are greatly deformed and refined with uniform size distribution; and overall relative density is 96% and the main deformation zone reaches full density. Microhardness is greatly improved by an increase of 137.93%, that is to say the average value increase from l 0.15Mpa to 24.12Mpa. 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.

关 键 词：纯钼粉 包套等径角挤压 塑性变形行为 致密化行为 

分 类 号：TG376[金属学及工艺—金属压力加工] TF124[冶金工程—粉末冶金]