Microstructure, mechanical properties and tribocorrosion characteristics of (Mo1-xCrx)5Si3 alloys

(Mo1-xCrx)5Si3 alloys were prepared by vacuum arc melting technique. The microstructure and mechanical properties of (Mo1-xCrx)5Si3 alloys were characterized using a scanning electron microscope (SEM), X-ray diffraction (XRD) and nano-indentation tests. The tribocorrosion characteristics of the alloys were investigated using a tribocorrosion tester in 3.5 wt% NaCl solution. The results revealed that the thermal expansion anisot-ropy ((CTE(c)/CTE(a))) of the (Mo1-xCrx)5Si3 alloys decreased from 2.25 to 1.45 with increasing Cr content. The Cr-alloyed (Mo1-xCrx)5Si3 alloys exhibited a high hardness, and their fracture toughness, ratios of H3/E2 and H/E were improved. (Mo1-xCrx)5Si3 alloys showed a strong wear-corrosion combined effect, and an opposite trend between friction coefficient and OCP values was observed during the tribocorrosion tests. The tribocorrosion resistances of (Mo1-xCrx)5Si3 alloys were better than that of 0Cr18Ni9 stainless steel due to the formation of Cr2O3-MoO3-SiOx protective films. The (Mo0.8Cr0.2)5Si3 alloy exhibited the best tribocorrosion characteristics with a low friction coefficient and wear rate. For the 0Cr18Ni9 and Mo5Si3 alloy, pure wear (Vw) was dominant, nevertheless, corrosion-induced wear (Vcw) was the main tribocorrosion mechanism of (Mo0.8Cr0.2)5Si3 alloy.