Effect Of Rare Earth For Microstructure And Properties Of Extruded Az80Alloy

Magnesium alloys containing rare-earth are among the best light weightstructural materials with a good capability, significant latent plastic deformability highstrength-to-weight ratio and excellent mechanical properties. The microstructure and mechanical properties of AZ80magnesium alloys through semi continuous casting,solution heat treatment and hot-extrusion containing RE were investigated.The microstructure of AZ80magnesium alloys containing RE through semi continuous casting were analyzed by means of optical microscopy(OM), X-Ray Diffraction,Scanning Electron Microscope(SEM), Transmitting electron microscope (TEM). The effect of RE on microstructure of casting ingots were systematically studied.Tensile strengthob,yield strengthao.2and elongation of above alloys with different chemical constitution and working were determined. Microstructure evolution of AZ80alloys containing RE via solution heat treatment and hot extruding were analyzed, strengthening mechanism,the effect of treatment and hot extrusion on mechanical properties of AZ80alloys containing RE, fractography of the alloys subjected to homogenization and hot extruding,was evaluated.The research results showed that with the addition of rare-earth in the AZ80alloy, the microstructure of the semi-continuous casting alloys could be refined.The morphology and distribution of the β-phase were gradually changed from irregularly network to island-like distribution.Acicular-shape RE rich phase dispersed on grain boundary and rent the basal body of the alloy.The defects, such as cavity, shrinkage porosity and void, etc, can be eliminated by hot extrusion. The microstructures of the extruded alloys possess the features of dynamic recrystallization, the grain size was significantly reduced, and the tensile properties were increased obviously as well, the max value of the tensile strength and the yield strength are390MPa,250MPa respectively. With adding of RE, sizes of grains were refined obviously.After hot-extrusion+ageing condition, the AZ80alloys fail in mixed mode and the fractures were decorated with ample dimples, cleavage steps and tearing edges.With addition of RE, the more and deeper of the dimples, and the more enhanced ductile rupture in nature.The flow stress behavior of AZ80+Y alloy was influenced by temperature and strain rate. With the increasing of strain rate and decreasing of temperature, the flow stress is increasing gradually. The flow stress of the alloy could be symbolized by a hyperbolic-sine-type equation expressed as ε=2399.14[sinh(0.012192σ7)]5.96exp[-149.45/(RT)]...