Low-cycle Fatigue Behavior and Microscopic Morphology of Fatigue Crack Structure of Al-Cu-Ag-Fe-Mg-Zr-Er Alloy in The Aging Treatment

Abstract Al-Cu-Ag-Fe-Mg-Zr-Er alloy with different content of Er addition was prepared by using metallurgy processing. The Al-4.5%Cu-0.5%Ag-0.35%Fe-0.38%Mg-0.1%Zr-xEr alloy phase and its refinement mechanism were studied with SEM. Tensile and fatigue tests were performed for the alloy in the state of deformation treatment condition. The microstructural observations reveal that the addition of 0.2% rare earth Er can effectively refine the grain structure of Al-Cu-Ag-Fe-Mg-Zr-Er alloy. It improves room temperature tensile strength, yield strength, and elongation at break. Under the condition of low cycle fatigue loading, Al-4.5%Cu-0.5%Ag-0.35%Fe-0.38%Mg-0.1%Zr-0.2%Er alloy shows a cyclic strain hardening in the cyclic stress response curves, which mainly depends on forming complex dislocation configurations. The accumulation of slip bands at the front of the grain boundary will lead to intergranular fracture of the material.