Effects Of Si/Al/Ti On Mechanical And Ignition-proof Property Of Mg-4Zn-3.5Y-0.8Ca Alloys

As a kind of nonferrous metal, magnesium alloy was widely used in aeronautics, astronautics and automobile industry with the requirement of saving energy resources and environmental protection. It is even lighter than aluminum alloy. It has the advantages of high special strength, special rigidity, damping property and electromagnetic shielding. As a lightweight material, magnesium alloy is increasingly used in automobile and electric industry in recent years. For the promotion of mechanical property of Mg-4Zn-3.5Y-0.8Ca ignition-proof magnesium alloy, the optical microscope were employed to investigate the influence of various addition of silicon, aluminum, titanium on the microstructure of Mg-4Zn-3.5Y-0.8Ca alloy. The alloy components were analysesed by using scanning electron microscope(EDS) and tensile property and ignition point of magnesium alloys were tested, The results of the paper are as follows:1. When silicon was added into Mg-4Zn-3.5Y-0.8Ca ignition-proof magnesium alloy, tensile property are improved and Mg₂Si phase was found in grain boundary. Some of Al₂Y can be surrounded by Mg₂Si and change shape into polygon, which lower the cut apart trend on matrix.2. When appropriate aluminum was added, the solid solubility of Zn in a-Mg was increased, grain boundary became thinner and even fine, a-Mg dendrites were broken, MgZn phase precipitated out form a-Mg were increased and the tensile property improved. But more Al₂Y phases are formed and the tensile property is decreased when an excessive of aluminum was added.3. When appropriate titanium was added, the solid solubility of Zn in a-Mg was increased, grain boundary became thinner, a-Mg dendrites were broken, MgZn phase precipitated out form a-Mg were increased and the tensile property improved. But the titanivim will react with silicon and consume each other when excessive of titanium was added.4. When Si was added, the ignition point decreased owing to the consumption of Ca through the formation of Mg2Si/CaMgSi and modification of Mg2Si phase. When aluminum was added into Mg-4Zn-3.5Y-0.8Ca-0.5Si alloy, the ignition point decreased because of the consumption of yttrium and formation of more Mg2Si phase. When adding titanium element into Mg-4Zn-3.5Y-0.8Ca-0.5Si alloy, the melt is purified, and excessive titanium results in the increase of ignition point because of the consumptions of ferrum and silicon element.5. When adding 0.8wt%Al, 1.3wt%Ti, 1.5wt%Ti into the Mg-4Zn-3.5Y-0.8Ca-0.5Si alloy respectively, the tensile strength of the alloy increases to 189 MPa> 192 MPa, 190 Mpa and ignition point is 710°C, 770°C> 820 °C respectively. When adding 0.2wt% Ti into the Mg-4Zn-3.5Y-0.8Ca alloy, the tensile strength is increased to 241 MPa.