EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Additive manufacturing has shown great potential for the development of high-performance high entropy alloys (HEAs), which is partially correlated to the fact that the rapid solidification within the melt pool could facilitate the formation of supersaturated metastable solid solutions. In this work, we introduce a metastable non-equiatomic FeMnCoCr HEA produced by selective laser melting (SLM) and post-annealing. The microstructure of the as-SLM processed sample is composed of two phases, i.e., face-centered cubic matrix and hexagonal close-packed martensite. Also, there are a number of 100 nm sized oxides enriched with Mn. After heat treatments at 500 ℃, 600 ℃, 700 ℃, 800 ℃ and 900 ℃ for 30 min, the tensile behavior and microstructure evolution are analyzed. It is found that the tensile properties and the phase metastability are maintained against heat treatment even at 900 ℃, compared to that of the as-SLM processed material. The mechanisms responsible for the mechanical and phase stabilities are discussed in terms of the special hierarchical microstructure of the SLM processed metastable HEA.