Processing and Properties of MoSi_2-Nb Composites

摘要

Powder processing techniques for MoSi_2 composites are described. The effect of Nb morphology on the fracture resistance of the composites was studied. Discontinuous random Nb particles or fibers deflected cracks that propagated through the MoSi_2 matrix. However, this did not result in any improvements in toughness (as measured from the area under flexural stress-displacement curves). Aligned Nb fibers oriented perpendicular to the direction of matrix crack propagation directly participated in the fracture of the composite; these fibers toughened MoSi_2. However, there was an effect of the diameter on the fracture behavior of the aligned fibers. The effect of fiber diameter on fiber-matrix separation could be explained through the load carrying capacity of the fibers and the ability of the fiber-matrix interface to separate.