Mechanical Behavior Of Al-Mg-Ce Alloy Processed By Equal Channel Angular Pressing

The equal-channel angular pressing(ECAP) has emerged as a widely-known procedure for the fabrication of ultrafine-grained metals and alloys.The equal channel angle pressing can refine the microstructures of materials and thus improve the mechanical properties of materials by introducing severe shearing plastic deformation without changing the cross section.In this investigation,the ECAP processes with different routes and passes have been conducted for the Al-4%Mg-0.3%Ce alloy.The microstructures as well as tensile and the low cyclic fatigue properties of the ECAPed Al-4%Mg-0.3%Ce alloy have been studied.In addition,the morphologies of the tensile and fatigue fracture surfaces for the ECAPed Al-4%Mg-0.3%Ce alloy are observed and analyzed using scanning electron microscope,and the corresponding tensile and fatigue failure mechanisms are determined.The microstructural observations of the Al-4%Mg-0.3%Ce alloy reveal that the average grain size is about 1μm after one pass of ECAP,and about 0.5μm after two passes of ECAP.The results of tensile experiments show that the ECAPed Al-4%Mg-0.3%Ce alloys give the higher yield strength.Under the tension loading condition,the shear fracture occurs for the Al-4%Mg-0.3%Ce alloys ECAPed with different passes and routes,while the normal tension break takes place for the conventional hot extruded Al-4%Mg-0.3%Ce alloy.The results of low-cyclic fatigue tests reveal that for the conventional hot-extruded and ECAPed Al-4%Mg-0.3%Ce alloys,the relation between elastic and plastic strain amplitudes with reversal cycles to failure shows a monotonic linear behavior,and can be well described by the Basquin and Coffin-Manson equations,respectively.In addition,at the higher total strain amplitudes,a serrated flow can be observed on theσ-εhysteresis loop for the conventional hot-extruded and ECAPed Al-4%Mg-0.3%Ce alloys.It means that the so-called dynamic strain aging takes place during fatigue deformation.The fractographic results reveal that under tensile loading condition,the Al-4%Mg-0.3 %Ce alloys ECAPed with different passes and routes exhibit the typical ductile fracture, while under low-cycle fatigue loading condition,the cracks initiate transgranularly at the surface of fatigue samples and propagate in a transgranular mode.