ABSTRACT

A near-equiatomic FeCoNiCuAl High-entropy alloy (HEA) was produced using laser powder bed fusion (L-PBF) pre-alloy powder. Microstructural characteristics and tribological properties of L-PBF specimens under various volumetric energy densities (VEDs) were investigated in detail. The results showed that the phase of L-PBF specimen consisted of BCC matrix + Cu-rich B2 precipitate. The microstructure of L-PBF specimen largely consisted of columnar grains perpendicular to the melt pool boundary (MPB) direction owing to the epitaxial growth along the temperature gradient. The preferred orientation of the L-PBF specimen was gradually transformed from the order of <001> to <101> as the VED rose. Larger size precipitates re-appeared and wider MPB were formed upon faster remelting and steeper cooling as a result of higher VED. Compared to the components produced by Spark Plasma Sintering, L-PBF specimens presented better wear resistance owing to the ultra-fine substructure and nano-scaled precipitates. In addition, the L-PBF specimen produced with 83 J/mm³ VED exhibits the highest elastic strain to failure (H/E_r ) and yield stress (H ²/E _r ³).

摘要

使用激光粉末床熔合（L-PBF）预合金粉末生产了近等原子的FeCoNiCuAl高熵合金（HEA）。详细研究了L-PBF样品在各种体积能量密度（VED）下的微观结构特征和摩擦学性能。结果表明，L-PBF试样的相由BCC基质+富Cu的B2沉淀组成。由于沿温度梯度的外延生长，L-PBF试样的微观结构主要由垂直于熔池边界（MPB）方向的柱状晶粒组成。L-PBF标本的首选方向逐渐从<001>变为<101>，作为VED玫瑰。由于较高的VED，在更快的重熔和更陡峭的冷却下，会再次出现更大尺寸的沉淀物并形成更宽的MPB 。与火花等离子烧结生产的组件相比，L-PBF样品由于具有超细的亚结构和纳米级析出物而具有更好的耐磨性。此外，以83 J / mm ³ VED制成的L-PBF样品表现出最高的断裂弹性应变（H / E _r ）和屈服应力（H ² / E _r ³）。