Fabrication and microstructure of MoSi2/Al2O3 functionally graded material

MoSi2/Al2O3 functionally graded materials (FGM) with alumina contents varying from 20 to 80 vol% have been fabricated using field-activated pressure-assisted reaction synthesis (FAPARS) from molybdenum, silicon and alumina. Reactant mixtures with different compositions were stacked in a variety of sequences. Under these conditions, a reaction is initiated by field activation and completed within a short period of time. It is demonstrated that this is an effective method to suppress diffusion and reactions between the different layers during the densification. The combustion reactions were conducted under a load to enhance the densification of the composition-graded composites. Microstructure morphology and interface elements distribution were observed and analyzed. The electrical resistivity of the as-obtained FGM varies by more than 10 orders of magnitude across the FGMs. (orig.)