Microstructures, Mechanical and High-Temperature Tribological Properties of Dual-Phase Fe50Mn30Co10Cr10 High-Entropy Alloy Fabricated by Laser Metal Deposition

The dual-phase Fe50Mn30Co10Cr10 (atomic percent, at.%) high-entropy alloy (HEA) was fabricated successfully through a laser metal deposition process. Fe50Mn30Co10Cr10 HEA consisted of face-centered cubic (FCC) γ and hexagonal close-packed (HCP) ε phases, with an alternating distribution of equiaxed and columnar grains. The microhardness, tensile strength and elongation of the alloy were 270 ± 20 HV, 689 MPa and 38%, respectively. After tensile deformation, many HCP ε phases were generated inside and at the boundaries of FCC γ grains because of the transformation-induced plasticity effect. The content of the HCP ε phase increased because of tensile deformation, resulting in a 75% decrease in the average grain size of the samples. Under the effect of dispersion strengthening, the strength, microhardness and plasticity of the material were greatly enhanced, with the product of strength and elongation up to 26.2 GPa%. The average friction coefficient and wear rate of the alloy were 0.43 and 1.88 × 10−5 mm3/N/m at 400°C, respectively, which were 38.6% and 81.6% lower than those at room temperature, showing great high-temperature wear resistance. The main wear mechanism of the alloy at 400°C was oxidative wear, accompanied by abrasive wear and delamination.