Microstructure and mechanical properties of Mg-2Al-xSi magnesium alloy

The Mg-2Al-xSi(x=0.50,0.75,1.0 and 1.25) magnesium alloy ingot has been cast.Its cast microstructure and mechanical properties have been investigated.The results indicate that the microstructure is composed mainly of α-Mg matrix,β-Mg17Al12 and Mg2Si phases.At the condition of w(Si)1.0%,the average size of Chinese script type Mg2Si phases is decreased gradually with the increasing of Si contains,the size decreased from 65 μm when the alloy is Mg-2Al-0.5Si down to 38 μm while the alloy is Mg-2Al-1.00Si.The average size of lump phase(Mg2Si) is increased when increase Si content,it is increased from 14 μm when the alloy is Mg-2Al-0.75Si up to 36 μm while the alloy is Mg-2Al-1.25Si.The hardness of the alloy is increased with the increasing of Si,it is increased from HV48.6 when the alloy is Mg-2Al-0.5Si up to HV59.1 while the alloy is Mg-2Al-1.25Si.The normal temperature properties and high temperature properties are excellent,the tensile strength and elongation of Mg-2Al-0.75Si are 145 N/mm2 and 7.0% at room temperature,while at high temperature(423 K)are 130N/mm2 and 10.0%,the fracture character of the alloy is quasi-cleavage fractures.