Cavitation behavior during tensile deformation at room temperature in fine-grained pure magnesium

Abstract

Cavitation behavior associated with grain boundary sliding at room temperature was investigated using fine-grained magnesium (Mg) specimens produced by extrusion or high-pressure torsion. Regardless of the process method, flow stress in both of Mg specimens depended on the tensile strain rate, and the strain rate sensitivities (m-values) were determined to be approximately 0.3 at low strain rates. Deformed microstructural observations revealed that many cavities were formed at grain boundaries and grain boundary triple junctions, even during the plastic deformation at room temperature. The size and density of such cavities increased with the progression of deformation. The majority of cavities were controlled by plasticity, and the cavity growth rate was similar to those typically observed in superplastic Mg alloys subjected to elevated temperature tensile tests. In addition, initial basal texture was unlikely to affect these cavitation behaviors, e.g., cavity growth rate.