Abstract
This article reports the effect of individual additions of Pb and Y on the precipitation sequence and mechanical properties of AZ91 magnesium alloy. Discontinuous phase is greatly suppressed with Pb addition, since Pb in solid solution effectively reduces the diffusion of Al and Mg atoms, which is significant for the formation and growth of discontinuous phases. Suppression of the discontinuous phase is also obtained with Y addition but in lesser extent. Besides, addition of Y introduces Al2Y phase which significantly refines the grain size by acting as potential nucleants for Mg grains. Pb addition moderately reduces the strength properties whereas improved mechanical properties are obtained with Y addition due to the formation of hard intermetallic Al2Y phase and refine grain size.
