Study on the wear resistance and mechanism of AlCrCuFe2NiTix high-entropy surfacing alloys

Abstract

The revolutionary design concept of high-entropy alloys has brought new opportunities and challenges to the development of advanced metal materials. In this work, the design idea of a high-entropy alloy is combined with the characteristics of flux cored wire, and AlCrCuFe2NiTix high-entropy flux cored wires were prepared. AlCrCuFe2NiTix high-entropy surfacing alloys were prepared using gas metal arc welding technology. The wear properties of AlCrCuFe2NiTix high-entropy surfacing alloys were analysed using an MFT-4000 reciprocating friction and wear tester. The phase composition and microstructure of AlCrCuFe2NiTix high-entropy surfacing alloys were analysed using XRD, SEM, EBSD, and TEM, and the strengthening mechanism and wear mechanism of the alloy were discussed. The results show that AlCrCuFe2NiTix high-entropy surfacing alloys are composed of the BCC/B2 + FCC phase. With increasing Ti content, the Laves phase begins to precipitate and exists stably. The microstructure of the alloy presents a typical dendritic structure, and the DR region is rich in Fe, Cr, Al and Ni. The BCC and B2 phases are coherently distributed in the dendrites with a spinodal decomposition network structure. The ID region is rich in Cu and Ti, and the Cu-rich FCC phase is segregated in the form of nanoparticles in the ID region, while the lamellar Laves phase precipitates in the ID region. With increasing Ti content, the microhardness of AlCrCuFe2NiTix high-entropy surfacing alloys shows an increasing trend, while their wear loss, friction coefficient, specific wear rate and other indicators show a trend of first decreasing and then increasing. The maximum microhardness is 597 HV, and the minimum specific wear rate is 9.1606 × 10−8 mm3/N mm. This is mainly because the precipitation of the B2 coherent phase and Laves phase hinders the movement of dislocations, resulting in an improvement in the strength and microhardness of the alloy. However, excessive Ti addition causes the Laves phase to increase sharply and segregate in the ID region, which is extremely prone to stress concentration during dislocation movement, thus inducing crack initiation. The fractured Laves phase exacerbates the grain-abrasion of the alloy and reduces its wear resistance.