Quasisuperplasticity

Quasisuperplasticity refers to a phenomenon observed in certain materials, typically ceramics or intermetallics, where significant plastic deformation occurs at elevated temperatures, approaching or exceeding the strain levels seen in superplasticity, but with distinct underlying mechanisms. Unlike true superplasticity, which relies on grain boundary sliding as the primary deformation mode, quasisuperplasticity often involves a combination of deformation mechanisms. These can include diffusion creep, grain boundary sliding accommodated by diffusional creep, and possibly some dislocation activity. The term "quasisuperplasticity" is used because the macroscopic behavior—large elongations before fracture—resembles superplasticity, but the microscopic processes are not solely dominated by grain boundary sliding.

This phenomenon is typically observed in materials with relatively large grain sizes compared to those required for conventional superplasticity. The higher temperatures at which quasisuperplasticity occurs facilitate atomic diffusion, which plays a crucial role in accommodating the deformation and preventing premature fracture. Understanding quasisuperplasticity is important for designing and processing advanced ceramic and intermetallic components that require significant formability at high temperatures, such as in aerospace or energy applications. The ability to achieve large deformations without fracture, even if through different mechanisms than true superplasticity, offers significant advantages in manufacturing complex shapes.