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(Al_(0.5)Cr_(0.9)FeNi_(2.5)V_(0.2))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 sintering(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.
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