Anelastic deformation of magnesium and its alloys – A review

The deformation of Mg is made up of elastic, anelastic and plastic components. Unlike the elasticity and plasticity which have been widely studied, the anelasticity has been routinely ignored in many published works when characterising the behaviour of Mg and its alloys, due mainly to the difficulty in measuring the small region of anelasticity during deformation. This paper reviews the anelastic deformation of Mg and Mg alloys, covering its potential causes, affecting factors, and its implications on several material properties. The evidence from the literature suggests two possible mechanisms which may be responsible for the anelastic deformation: reversible {10 $\bar{1}$ 2} twinning and reversible incipient kink bands in the form of basal dislocation loops. Several factors, such as grain size, loading direction, solute concentration, precipitation, strain rate and temperature, are also observed to influence the magnitude of anelasticity. A direct consequence of anelastic deformation is the variation of elastic modulus values. This can lead to ambiguities and errors in determining stiffness, yield strength and fatigue behaviour if a constant nominal elastic modulus is used in engineering analyses. This review paper has shown that the anelastic deformation of Mg remains under-reported and suggested some possible directions for future research.