Role of Lanthanum in Grain Refinement and Tensile Properties of Cast Mg–La–Zr Alloys

Abstract

In a previous investigation, a combined addition of zirconium and lanthanum was found to confer more marked grain refining than zirconium alone. The present experimental study confirmed this result. However, in this study, the microstructure was examined with more attention to the form of the zirconium-rich coring in the grain refined structures. It was concluded that although the average apparent grain size decreases with an addition of lanthanum, this is in part because grain growth takes place in the Mg–Zr alloy, while the suppression of grain growth occurs with an addition of lanthanum as small as 0.5%.