Using C to enhance the wear resistance of AlCrFe2Ni4Ti2 high-entropy alloy via replacing brittle phases by in-situ formed TiC in a matrix with improved ductility.

The wear resistance of high-entropy alloy (HEA), AlCrFe 2 Ni 4 Ti, can be enhanced by increasing the Ti content, which raises the hardness of the alloy due to the formation of harder phases, including an L2 1 phase with disordered-BCC nano-precipitates, a η -Ni 3 Ti hexagonal phase, and a MgZn 2 -type Fe 2 Ti Laves phase. However, these hard but relatively brittle phases have negative influences on the wear resistance of the alloy if their amount exceeds a certain level, especially when large impact forces or large fluctuations in wearing force are involved. In this work, we added carbon to AlCrFe 2 Ni 4 Ti 2 to reduce the Ti-containing brittle phases and form in situ TiC particles in the metallic matrix with improved ductility. Samples of AlCrFe 2 Ni 4 Ti 2 C X (x = 0, 0.5 and 1.0, in molar ratio) were fabricated by arc melting. The fabricated HEA-matrix with in situ TiC particles showed improved ductility, e.g., the compressive ductility was increased by up to 30%, along with increased ultimate compressive strength, although the yield strength was slightly decreased, compared with the alloy without carbon addition. Wear tests demonstrated that the HEA with in situ TiC particles showed consequently enhanced wear resistance (10%–19% higher). This study demonstrates an effective approach to modify the high-entropy alloy for enhanced wear resistance by eliminating or minimizing Ti-containing brittle phases using carbon to react with Ti, forming in situ TiC particles in a HEA matrix with improved ductility. • High-entropy AlCrFe 2 Ni 4 Ti 2 -C X alloys with in situ synthesized TiC particles were prepared via arc melting. • The added carbon reacted with Ti to form in situ TiC particles, leading to improved ductility through reducing brittle η -Ni 3 Ti and Laves Fe 2 Ti phase. • Wear resistance of the alloy was enhanced due to the in situ TiC particles and improved toughness. • Surface and subsurface cracks caused by wear decreased due to improved ductility/toughness, helping lowering stress concentrations and thus wear. [ABSTRACT FROM AUTHOR]