The effect of Gd element and solution treatment on the microstructure of AZ31 magnesium alloy and its kinetic model

The influence of Gd element and solution treatment on the microstructure of AZ31 alloy was investigated in this paper. The microstructure and phase composition were characterized by OM, SEM, EDS and XRD. The results indicate that Mg17Al12 eutectic phase, scattered along the grain boundary, is suppressed effectively with Gd addition and the acicular Al2Gd superlattice with lamellar distribution is formed. Furthermore, the grain size of AZ31 alloy is also refined with Gd addition. In the subsequent process of solution, the migration and growth of Al2Gd phase conforms to Ostwald Ripening Theory. The morphology of Al2Gd phase becomes granular and scatterd in matrix uniformly after solution for 16 h at 813 K. (C) 2015 Elsevier B.V. All rights reserved.