Ultrashort-time liquid phase sintering of high-performance fine-grain tungsten heavy alloys by laser additive manufacturing. (10th November 2021)

• Record Type: Journal Article
• Authors: Zhou, Shangcheng; Liang, Yao-Jian; Zhu, Yichao; Wang, Benpeng; Wang, Lu; Xue, Yunfei
• Is Part Of: Journal of materials science & technology. Volume 90(2022)
• Page Start: 30
• Page End: 36
• Publication Date: 2021-11-10
• Subjects: Tungsten heavy alloy -- Laser additive manufacturing -- Liquid phase sintering; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2021.02.032
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: A laser ultrashort-time liquid phase sintering (LULPS) technique was developed. LULPS prepared a tungsten heavy alloy (WHA) with high W content of 90 wt.%. LULPS obtained a dense WHA with small W particle size of ~1/3 of that in LPS WHAs. WHA by LULPS showed ~40% higher yield strength than LPS WHAs. WHA by LULPS exhibited enhanced susceptibility to adiabatic shear banding. 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 (Al0.5 Cr0.9 FeNi2.5 V0.2 ) 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.