Microstructure and Mechanical Properties of Mg-Al Alloys with Low Aluminum Contents

The microstructure and mechanical properties of Mg-Al alloys with aluminum contents below 3wt% were studied by means of optical microscopy,scanning electron microscopy,X-ray energy dispersive analysis,X-ray diffraction and tensile testing machine.The results show that the microstructure of as-cast Mg-Al alloys with low Al content was composed of α-Mg and β-Mg17Al12 phases.The α-Mg solid-solution was equiaxed dendrite.With the increase of Al content,the size of α-Mg dendrites with a six-fold symmetrical rosette decreased,and the branch became dispersed.Mechanical properties increased basically with the increase of Al content.The tensile strength,yield strength and elongation of the alloy with 2.6wt%Al were 178.8 MP,62.3 MPa and 11.3%,respectively.