Studies on synthesis and microstructure evolution of multiphase in-situ composites based on Mo-Cr-Si system

Abstract

This paper presents the results on in-situ synthesis of refractory metal-intermetallic composites (RMICs), Mo-16Cr-4Si and Mo-11Cr-9Si (wt.%) multiphase alloys and their characterization. The alloys were prepared from the oxides of molybdenum and chromium by their coreduction with Si as reductant. Exothermic nature of the synthesis reactions resulted in the formation of consolidated composite as a product in a single step. As-reduced alloys were remelted by arc melting and heat treatment was given. The evolution of phases and the microstructure were studied by XRD, SEM, and EDS analysis. The multiphase microstructure consist of the silicide phases (Mo,Cr) 3 Si + (Mo,Cr) 5 Si 3 for hypereutectic and (Mo,Cr) 3 Si phase distributed in bcc matrix comprising essentially a solid solution of (Mo,Cr) for hypo-peritectic composition. Comparative studies of the synthesized alloys were also carried out to the composition, phases, microstructure, hardness and their oxidation behavior.