Mg-La-Zr合金の延性と変形組織

Abstract

In order to gain insight for developing fine-grained magnesium alloy materials through plastic deformation, Mg-Zr, Mg-La, and Mg-La-Zr alloys, prepared from pure magnesium and lanthanum metals, and a Mg-33Zr master alloy were tensile tested at room temperature and 150ºC. The microstructures were examined by optical microscopy, X-ray diffraction analysis, and EBSD analysis to establish the characteristics of deformed portions of the tensile-tested specimens. Whereas the elongation values of Mg-La and Mg-La-Zr materials tested at room temperature decreased with lanthanum content, the materials tested at 150ºC maintained a similar level of elongation regardless of lanthanum content. EBSD analysis of the deformed materials of the Mg-La-Zr alloys tensile-tested at room temperature and 150ºC revealed that the microstructures of primary αMg consisted of approximately 50% ultrafine grains of 0.5 to 1.5 μm in size. About 70% of the eutectic αMg grains was found to be approximately 0.1 μm in size, suggesting that microstructural transformations that take place through deformation processes may help to enhance ductility.