Abstract
The high-temperature compressive yield strength of discontinuously reinforced MoSi 2 composites can be several times greater than that of single-phase MoSi 2. To understand the mechanism responsible for this observed strengthening, particulate reinforced MoSi 2 composites with 15–45 vol.% SiC, TiB 2, ZrB 2, and HfB 2, and average diameters ranging from 1 to 5 μm were produced by the XD™ process. The high-temperature yield strength of these alloys was found to be a function of particle size, volume fraction, and reinforcement distribution. These three variables can be reduced to a single quantity, interparticle spacing. Specifically, the yield strength was found to be proportional to the inverse square root of the interparticle spacing. This indicates that the operative strengthening mechanism for these composites may be interphase barrier strengthening, a generalization of Hall-Petch strengthening where the particle-matrix interfaces act as obstacles to dislocation motion. The strength of these composites was found to be independent of particle type when interparticle spacings were taken into consideration.
Published Version
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