Predicting grain boundary sliding in metallic materials

Abstract

Grain boundary sliding (GBS) significantly influences the mechanical properties of polycrystalline metals and alloys. A comprehensive set of GBS data spanning 70 years and encompassing 12 material classes under various deformation conditions has been compiled. Analysis identifies strain (ε) and grain size (d_g) as the primary factors influencing GBS displacement in agreement with a previously developed basic model, revealing a linear dependence of GBS displacement on strain and grain size. A major factor in the model is the strain enhancement factor, i.e., the ratio between the creep strain due to GBS and the total creep strain. Utilizing the average strain enhancement factor from the GBS data (0.2), the model demonstrates predictive capabilities across various materials (Fe, ferritic steels, austenitic steels, Al, Mg, Cu, Zn, and their respective alloys), grain sizes (nanometers to micrometers), and strain levels (0.1-161%) without significant loss in statistical accuracy. Application to creep cavitation further illustrates the usefulness of the model.