Observation of weakened and strengthened creep behavior in Ti/TiB(w) composites at high temperatures

Dispersing reinforcements in a ductile matrix is one method of strengthening metallic materials at high temperatures. Although this method generally strengthens the material, it is predicted that concomitant diffusion weakens it when heterogeneous stresses around the reinforcements are accommodated by rapid diffusion along the matrix/reinforcement interface. Here we show weakening with increasing volume fraction of reinforcements under low strain rates and strengthening under high strain rates using Ti/TiB(w) composites at 1473 K. The criterion of weakening or strengthening is established by the diffusional-accommodation rate considering the accommodation process of the misfit strain between the matrix and reinforcements by diffusion.