发表机构
Texas A&M University; Colorado School of Mines; Argonne National Laboratory（德克萨斯农工大学; 科罗拉多矿业学院; 阿贡国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过原位X射线成像揭示LP-DED中颗粒惯性（高韦伯数）主导大孔隙形成，能量密度增加加深颗粒穿透并增大孔隙，为控制孔隙率提供物理依据。
AI 中文摘要
激光粉末吹送定向能量沉积（LP-DED）在工艺和材料方面具有灵活性，且生产率高（约5千克/小时），但工艺诱导的孔隙常常损害机械性能。本研究利用原位X射线同步辐射成像，比较了Ti-6Al-4V（Ti64）和不锈钢316L（SS316L）中的孔隙形成机制，重点关注颗粒动力学与热物理性质之间的相互作用。研究识别出四种不同的孔隙形成机制，其中大多数大孔隙源于入射颗粒撞击熔池后形成的空腔闭合。高韦伯数（We >> 1）控制着这一行为，表明颗粒惯性而非热物理性质差异是形成大孔隙的主要驱动力。研究表明，能量密度的增加导致熔池体积增大，从而促进颗粒更深的穿透。这种更深的穿透深度与孔隙直径的增加直接相关。虽然热物理性质次要地影响孔隙形成频率和空腔对称性，但颗粒惯性仍是主导因素。这些发现为理解和控制粉末吹送DED工艺中的孔隙率提供了物理基础。
英文摘要
Laser Powder-blown Directed Energy Deposition (LP-DED) offers flexibility for process and materials and high productivity (~5 kg/h), but process-induced pores often compromise mechanical properties. This study utilizes in-situ X-ray synchrotron imaging to compare pore formation mechanisms in Ti-6Al-4V (Ti64) and stainless steel 316L (SS316L), focusing on the interplay between particle dynamics and thermophysical properties. Four distinct pore formation mechanisms were identified, with most large pores originating from the closure of cavities formed behind incident particles impinging on the melt pool. High Weber number (We >> 1) governs this behavior, indicating that particle inertia, rather than thermophysical property differences, is the primary driver of large pore formation. The study demonstrates that increased energy density leads to larger melt pool volumes, facilitating deeper particle penetration. This greater penetration depth directly correlates with increased pore diameters. While thermophysical properties secondarily influence pore-formation frequency and cavity symmetry, particle inertia remains the dominant factor. These findings provide a physically grounded basis for understanding and controlling porosity in powder-blown DED processes.
