Effect of precipitates on dynamic impact damage mechanism of a selective-laser-melted FeCoNiCrMo0.2 high-entropy alloy

The selective laser melting (SLM) technology provides design ideas for the development of new high entropy alloys (HEAs) with exceptional mechanical properties. The microstructural control, especially precipitates, is an important way to improve the dynamic mechanical properties of the SLM-FeCoNiCrMo 0 . 2 HEAs. In this study, the effect of precipitates on the dynamic impact damage mechanism of SLM-FeCoNiCrMo 0 . 2 HEAs is revealed. Introduction of the nano-scale a-phase precipitates into SLM-FeCoNiCrMo 0 . 2 HEAs by quenching treatment leads to a transformation in dynamic impact damage mechanism from micro-cracks along columnar grain boundaries to micro-pores near the a-phase precipitates. The a-phase precipitates are considered to be able to disperse large reflected stress waves at the boundary and coordinate the deformation of columnar grains with different orientations on both side of the boundary, which hinder the propagation of the micro-cracks. The a-phase precipitates strengthened HEAs exhibits excellent dynamic mechanical properties, with the dynamic compressive strength and fracture strain reaching 2780 MPa and 0.37, respectively. This work provides theoretical support for the design of precipitates in the additive-manufactured FeCoCrNi-based HEAs with high impact performance.