Lattice structures and mechanical properties of FeCrNi medium-entropy alloy prepared by selective laser melting

Abstract

Metal lattice structural materials are widely used in aerospace, automotive industry, and other fields due to their advantages of lightweight, high specific strength, energy absorption, and porosity. High strength and toughness FeCrNi medium entropy alloy (MEA) was taken as the research object, and selective laser melting (SLM) was used to prepare FeCrNi medium entropy alloy lattice structure materials with four simulated lattice structures: BCC, BCCZ, FCC and FCC. The microstructure, mechanical properties, and deformation behavior of these materials were systematically studied.The results indicate that the FeCrNi medium entropy alloy lattice structure prepared by the skip scanning strategy has high node overlap quality, dense interlaced stacking of molten pools, and uniform and fine grains. When the relative density is similar, the specific strength and specific energy absorption values of BCC, FCC, BCCZ, and FCCZ lattice structures increase sequentially.The specific energy absorption of FeCrNi medium entropy alloy material with FCCZ lattice structure reaches 49.8J·g-1, significantly higher than that of Ti6Al4V and 316L stainless steel lattice materials.The finite element simulation analysis shows that the presence of Z-shaped pillars increases the apparent strength and stiffness of the lattice material, and leads to a transition in deformation behavior from bending dominated to tensile dominated, which is the main reason for the strength improvement of the FCCZ lattice structure.

Keywords

• selective laser melting
• medium entropy alloy
• lattice structure
• mechanical property