Microstructure,Properties And Homogenizing Treatment Of Er-Doped Al-Cu-Mg-Ag Alloy

Compared with commercial aluminum alloy,the Al-Cu-Mg-Ag alloy has exhibited better strength properties and heat-resistant properties,and it has became the focus of the research of heat-resistant aluminum alloy.The Erbium is a rare earth,which is rich in reserves.In this paper,based on the original alloy,Al-4.3Cu-0.7Mg-0.1Ag alloy containing different percent of Er were prepared.The effects of Er contents on microstructure,mechanical and electrical properties were investigated by the mean of XRD,OM,SEM,DSC.In this paper,the microstructures of the alloy after single-stage homogenization treatment and two-stage homogenization treatment were analyzed and discussed theoretically.The result can provide theories basis of Al-Cu-Mg-Ag-Er homogenizing process and the improvement of the quality of alloy ingot.The result of the research shows that the second-phases are mainly Al8Cu4Er phase and Al2Cu phase.The other phase also exists in alloy which is composed of Er element and the impurity of Fe.The Al8Cu4Er phase has better thermal stability.With Er addition in the range of 0.1%-0.3%,the effect of grain refining to as-cast alloy is obvious,the ultimate tensile strength of alloy is improved from 345 MPa to 439 MPa at room temperature.The elongation of the alloy is improved from 7.81%to 17.33%,and the hardness is enhanced from 118.73 HV to 136.24 HV.When Er content is over 0.3%,Er has litter effect on grain refining to as-cast alloy.The hardness and the ultimate tensile strength of alloy at room temperature not improve significantly.The elongation declines,but the persistence rate of hardness of the alloy which was processed at high temperature improves.The electric resistivity exhibits decrease first and then increase with the addition of Er.When the addition of Er is 0.1%,the electric resistivity reaches 37.81 n?·m which is the minimum.The best single-stage homogenization treatment is 495 ?×24 h.The Al2Cu phase is dissolved and the Al8Cu4Er phase remains stable after single-stage homogenization.The best two-stage homogenization treatment is 495 ?×24 h+530?×4 h.The overheated temperature is improved with the two-stage homogenization treatment.The Al8Cu4Er phase dissolves into the matrix,and the effect of homogenization is obviously improved.