Abstract
Liquid phase sintering (LPS) is a proven technique for preparing large-size tungsten heavy alloys (WHAs).However,for densification,this processing requires that the matrix of WHAs keeps melting for a long time,which simultaneously causes W grain coarsening that degenerates the performance.This work develops a novel ultrashort-time LPS method to form bulk high-performance fine-grain WHAs based on the principle of laser additive manufacturing (LAM).During LAM,the high-entropy alloy matrix(Al0.5Cr0.9FeNi2.5V0.2) and W powders were fed simultaneously but only the matrix was melted by laser and most W particles remained solid,and the melted matrix rapidly solidified with laser moving away,producing an ultrashort-time LPS processing in the melt pool,i.e.,laser ultrashort-time liquid phase sin-tering (LULPS).The extreme short dwell time in liquid (～1/10,000 of conventional LPS) can effectively suppress W grain growth,obtaining a small size of 1/3 of the size in LPS WHAs.Meanwhile,strong convection in the melt pool of LULPS enables a nearly full densification in such a short sintering time.Compared with LPS WHAs,the LULPS fine-grain WHAs present a 42％ higher yield strength,as well as an enhanced susceptibility to adiabatic shear banding (ASB) that is important for strong armor-piercing capability,indicating that LULPS can be a promising pathway for forming high-performance WHAs that surpass those prepared by conventional LPS.
基金项目
National Natural Science Foundation of China(51901023)
National Key Research and Development Program of China(2018YFB0703400)
NETL
NSTL
维普
万方数据