Impact of Samarium on Microstructural Evolution and Tribological Behavior of FeCoNiCr High-Entropy Alloys Fabricated by Laser Metal Deposition

In this paper, the microstructural evolution and tribological behavior of an FeCoNiCr alloy containing Sm fabricated by the Laser Metal Deposition technique were investigated. The study employs x-ray diffraction analysis, energy-dispersive spectroscopy, and friction coefficient measurements to comprehensively investigate the impact of Samarium (Sm) addition on the microstructural evolution and frictional behavior of high-entropy alloys (HEAs). Results reveal that the inclusion of 0.4-0.8 wt.% Sm effectively inhibits the formation of coarse phases at the interface between HEAs and 45 steel substrates, enhancing their bonding strength while inducing the precipitation of secondary phases within the HEA matrix. During frictional processes, distinct characteristics in friction coefficients in the friction pair between HEAs against 304 stainless steel beads and SiC beads are observed. Sm-added HEAs demonstrate relatively stable friction coefficients and different friction behaviors with various Sm content, which can be attributed to changes in friction mechanisms caused by formation of oxide particles as lubricant on the contact surface.