Interphase boundary sliding of two-phase (α/β), (β/γ) and (γ/α) CuZnSn alloy couples produced by solid-to-solid diffusion bonding

The sliding behavior of α/β, β/γ, and γ/α interphase boundaries of CuZnSn alloy diffusion couples produced by solid-to-solid diffusion bonding was investigated. Particular attention was paid to differences in hardness between two component phases. The slidings at these three types of interphase boundaries showed so-called slide softening, in which the sliding rates increased with sliding displacement at relatively low temperatures of 723–873 K. The sliding rate of interphase boundaries consisting of component phases with dissimilar hardness tends to be higher than those with similar hardness. Macroscopic sliding accompanied a local plastic deformation in the softer phase adjacent to the interphase boundaries. The present results support the mechanism that an interphase boundary sliding plays an important role in the structural superplasticity of fine-grained materials consisting of a hard and a soft phases.