PROCESSING AND MECHANICAL-PROPERTIES OF NIOBIUM-REINFORCED MOSI2 COMPOSITES

In this paper, we describe a framework for the processing of niobium-reinforced MoSi2 composites. As a part of the program, composites containing coated and uncoated niobium reinforcements were produced. Chemical compatibility between the coatings and the matrix was studied and the effect of the interface modification by the coating on the fracture toughness of the composites was investigated via four-point bending tests on chevron-notched samples. The results indicated that the coatings have a significant effect on the debonding at the reinforcement-matrix interface, which in turn can affect the damage tolerance of the composite. Also observation of the crack propagation in the composites suggests that the matrix failed at the early stages of loading. The results are discussed in terms of the mismatch between the elastic constants of the composite constituents.