The effects of Er content on microstructure of Al-Cu-Mg-Ag-Er alloy and electric resistivity

The Al-Cu-Mg-Ag-Er aluminum alloys with different Er contents were prepared in this experiment. The effects of Er content on microstructures of the as-cast and the extruded alloys, the electric resistivity were researched. The results show that when Er content is below 0.1%, Er has the effect of refining. With Er addition in the range of 0.1%-0.3%, the effect of grain refining to as-cast alloy is obvious. The dimension of second phase particles in extruded alloy decreases, and the number of second phases increases. When Er content is over 0.3%, Er has litter effect on grain refining to as-cast alloy. Er segregates at grain boundaries, and forms Al₈Cu₄Er. The number of second phase particles in extruded alloy increases, and the dimension is not changed obviously. The Al₂Cu and Al₈Cu₄Er do not dissolve in the matrix at 350 °C by hot extrusion, which shows good thermal stability of Al₂Cu and Al₈Cu₄Er. The electric resistivity exhibits decrease first and then increase as the addition of Er.