Microstructure and Properties of Al-Mg-Si-Li Alloys with Different Mg Content

Microstructure and properties of Al-Mg-Si-Li alloys with different Mg content were investigated. The microstructure was observed by optical microscopy, the phases were determined by X-rays diffractometry, the hardness was monitored by Vickers, the mechanical properties were determined by tensile tester, fracture morphology was conducted by scanning electron microscopy. The tensile strength and the elongation of the Al-Si-Li alloys is improved by the addition of magnesium. With the increment of Mg content, the alpha-Al is refined, the amount of primary Si decreases, the eutectic increases, and the mechanical properties of the alloys are improved. The alloys containing 3.0wt.% Mg has excellent strength and elongation. If the Mg content is too much, the alloys have poor mechanical properties as Chinese script Mg2Si are present.