Influence of MoSi2 on the microstructure and elevated-temperature wear properties of Inconel 718 coating fabricated by laser cladding

In the present study, the MoSi2 reinforced Inconel 718 composite coatings were fabricated by laser cladding, aiming at improving the hardness and elevated-temperature wear properties of Inconel 718 coating. The mixed powders of Inconel 718 with different contents of MoSi2 (0, 10 and 30 wt%) were utilized as the cladding materials. The microstructure and mechanical properties of the composite coatings were evaluated. The friction and wear properties of the composite coatings were examined from 30 °C to 800 °C in air sliding against Si3N4 counterpart. Results showed that the Inconel 718 coatings with different contents of MoSi2 were composed of the same matrix phase of γ-Ni(Cr, Fe) and Nb-rich Laves phase for 0 wt% MoSi2, Ni3Si/MoNiSi and Fe2Mo for 10 wt% MoSi2 as well as MoNiSi and MoFeSi for 30 wt% MoSi2, respectively. The topological close-packed effect of MoNiSi and MoFeSi as well as solution strengthening effect of γ-Ni(Cr, Fe) lead to the remarkable increase in the microhardness and mechanical properties of the Inconel 718 composite coating with 30 wt% MoSi2. The Inconel 718 coatings presented excellent wear resistance in the wide range of temperature with the increase of the content of MoSi2, which can be attributed to the Laves phases of MoFeSi and MoNiSi have excellent abrasive and adhesive wear resistance at medium-low temperature and the formation of smooth glazed layer containing MoO3 and MoO2 at high temperature.