The effect of mixed RE addition on microstructure and mechanical property was studied when the addition(wt.%) varying from 0,0.4,0.8 to 1.0.The results show that the addition of mixed RE has a great influence on properties and microstructure of Al-Cu-Mn alloy.With the increase of the addition of mixed RE,the tensile strength of the alloy increases,and has the peak when mixed RE is 0.4%,then it decreases when the addition exceeds 0.4%.With the increase of the addition of mixed RE,the microhardness of alloy matrix decreases quickly.

In order to solve the problem of complex structure and complicated manufacturing process and achieve the target of lightweight,choosing a fixed steel armrest of a bus as prototype,the aluminum alloy material ZL104 was selected to replace the original steel material and the structure optimization was achieved.The mold for die casting was designed by Pro/E software.The maximum cross-section was chosen as the parting plate and a mechanism of side pulling of core was chosen.Overflow tanks were set up at the end of the filling molten metal.The design can provid certain reference for industry practices.