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

(Mo 1-x Cr x) 5 Si 3 alloys were prepared by vacuum arc melting technique. The microstructure and mechanical properties of (Mo 1-x Cr x) 5 Si 3 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 anisotropy ((CTE(c)/CTE(a))) of the (Mo 1-x Cr x) 5 Si 3 alloys decreased from 2.25 to 1.45 with increasing Cr content. The Cr-alloyed (Mo 1-x Cr x) 5 Si 3 alloys exhibited a high hardness, and their fracture toughness, ratios of H3/E2 and H/E were improved. (Mo 1-x Cr x) 5 Si 3 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 (Mo 1-x Cr x) 5 Si 3 alloys were better than that of 0Cr18Ni9 stainless steel due to the formation of Cr 2 O 3 -MoO 3 -SiO x protective films. The (Mo 0.8 Cr 0.2) 5 Si 3 alloy exhibited the best tribocorrosion characteristics with a low friction coefficient and wear rate. For the 0Cr18Ni9 and Mo 5 Si 3 alloy, pure wear (V w) was dominant, nevertheless, corrosion-induced wear (V cw) was the main tribocorrosion mechanism of (Mo 0.8 Cr 0.2) 5 Si 3 alloy. • Tribocorrosion behaviors of the (Mo 1-x Cr x) 5 Si 3 alloys were investigated. • The fracture toughness of Mo 5 Si 3 alloy was improved by Cr alloying. • Oxide films (MoO 3 , Cr 2 O 3 and SiO x) enhance the tribocorrosion properties. • Tribocorrosion resistances of the alloys were better than that of 0Cr18Ni9. [ABSTRACT FROM AUTHOR]