Fracture Behavior and Grain Boundary Sliding During High-Temperature Low-Stress Deformation of AZ31 Magnesium Alloy

Low-stress high-temperature tensile-creep behavior of AZ31 Mg alloy was investigated to characterize microstructure evolution, uncover dominant creep mechanism and find a correlation with common creep models. The stress exponent, inverse grain size exponent and activation energy value were evaluated. Cavity nucleation from stress concentration sites, types of fracture surfaces and microstructural evidence of grain migrations were observed in crept samples that are indicative of Rachinger mechanism of grain boundary sliding (GBS). Experimental data reveal a reasonable correlation with Langdon's model. Further analysis on fracture behavior of this alloy in a wider range of stresses show that they follow Monkman-Grant model in predicting the fracture time.