High-Performance Tungsten Components via Low-Temperature Spray-Dried Powder and Low-Energy SLM: A Breakthrough for Refractory Metal Additive Manufacturing

Abstract

Tungsten's ultrahigh melting point and thermal stress-induced cracking pose significant challenges for additive manufacturing. To address this, we propose a novel strategy combining low-temperature spray drying with optimized heat treatment to fabricate spherical tungsten (W) powders with high sphericity (≥ 95%), narrow particle size distribution (10–50 μm), and excellent flowability (28 s/50 g). Compared to conventional plasma-spheroidized powders, our method reduces production costs and enables selective laser melting (SLM) at remarkably low energy densities (200–600 J/mm³), far below the typical range of 500–1500 J/mm³. Mechanistic analysis reveals that the tailored powder structure suppresses thermal shrinkage cracks by lowering the critical ratio of laser energy density to scanning speed (E/v ≤ 2). At E/v = 1.7 (170 W, 300 mm/s, 0.08 mm spacing), the printed components achieve a relative density of 94.1% (vs. 96% for high-energy SLM) and microhardness of 488 kg/mm², surpassing commercial cast tungsten (423 kg/mm²). Notably, nanoindentation tests demonstrate exceptional plasticity (indentation work: 0.204 kN·m/m²), comparable to single-crystal tungsten. This work not only establishes a low-cost pathway for refractory metal additive manufacturing but also provides a universal parameter framework (E/v threshold) to mitigate defects in high-melting-point alloys and improves the issues of element evaporation and combustion in additive manufacturing of refractory alloys.