Abstract

Two high-purity tungsten powders, produced via different manufacturing techniques, were characterized to determine size distribution, morphology, thermal properties, and flow characteristics and, thus, the likely suitability for Laser Powder Bed Fusion (LPBF) production. Specimens from duplicate builds were produced with the two powders and characterized for density, defect mechanisms, and thermal penetration into the substrate plate to compare apparent power densities. The first powder was a chemically reduced powder with irregular morphology and the second, a plasma spheroidized powder with highly spherical morphology. The latter was found to have tighter morphological control and size distribution, having a third of particles at the modal particle size in comparison to a fifth of the chemically reduced powder. This led to better flow characteristics, and an increase of 1.5 g cm⁻³ (1500 kg m⁻³) in the packing densities seen in the powder bed which corresponds to 57 pct theoretical density vs 50 pct theoretical density in the chemically reduced powder. As a result, the specimens produced from the plasma spheroidized powder had higher densities (97.3 vs 88.5 pct) and the dominant defect mechanism moved from lack of fusion dominated in the chemically reduced powder to cracking dominated in the plasma spheroidized. The plasma spheroidized powder also showed higher apparent power densities (effective absorptivities) as evidenced by an 80 pct deeper penetration of the laser into the substrate plate.

中文翻译：

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粉末特性对通过激光粉末床熔合（LPBF）生产的高纯钨制造质量的影响

抽象的

两种高纯度钨粉，通过对不同的制造技术进行了表征，以确定尺寸分布，形态，热性能和流动特性，从而确定激光粉末床聚变（LPBF）生产的适用性。用这两种粉末生产重复样品，并对其密度，缺陷机理和热渗透到基板的特性进行了比较，以比较视在功率密度。第一种粉末是化学还原的粉末，具有不规则的形态，第二种粉末是等离子球化的粉末，具有高度球形的形态。发现后者具有更严格的形态控制和尺寸分布，与化学还原粉末的五分之一相比，在模态粒径下具有三分之一的颗粒。这导致更好的流动特性，并增加了1.5 g cm在粉末床中看到的堆积密度为^-3（1500 kg m ^-3），对应于57％的理论密度与50％的化学还原粉末中的理论密度。结果，由等离子球化粉末生产的标本具有更高的密度（97.3 vs 88.5 pct），并且主要缺陷机理从化学还原粉末中占主导地位的熔融不足转变为等离子球化中占主导的裂纹。等离子体球化的粉末还显示出较高的视在功率密度（有效吸收率），这可通过将激光更深地穿透到基板中80％来证明。