Refinement effect of cerium, calcium and strontium in AZ91 magnesium alloy

Refinement effects of cerium (Ce), calcium (Ca) and strontium (Sr) additions to AZ91 magnesium alloy have been investigated. Results show that an addition of 0.8 wt.%Ce combined with either 0.2 wt.%Ca or 0.2 wt.%Sr has a significant refining effect, and a higher degree of refinement using Ce–Ca combination rather than Ce–Sr. EDS microanalysis and water-quenched microstructure observation were used to reveal the grain refinement mechanism. It is assumed that grain refinement is mainly due to the impeding effect on grain growth during solidification of Ce, Ca and Sr segregation on grain boundaries.