Effect of Al content on microstructure and mechanical properties of as-cast Mg-5Nd alloys

Abstract

The microstructures and mechanical properties of as-cast Mg-5Nd-xAl (x = 0, 0.8, 1.6, 2.4 and 3.0 wt%) were investigated by the optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and uniaxial tension test. The addition of 3.0 wt% Al led to the most significant grain refinement of Mg-5Nd alloy with the reduction of average grain size from 448 μm to 68 μm. The grain refinement was attributed to the formation of Al2Nd particles as the Al2Nd particles acted as effective grain refiners for the Mg matrix confirmed by XRD analysis, SEM observation, and crystallography calculation. The mechanical properties of as-cast Mg-5Nd alloy increased obviously after the addition of Al. The yield strength, ultimate tensile strength and elongation of the as-cast Mg-5Nd-3.0Al alloy were enhanced by about 45.3%, 72.4% and 264.0%, respectively, compared to as-cast Mg-5Nd alloy. The improvement of mechanical properties was mainly ascribed to the refined grains and secondary phase strengthening.