Microstructure And Properties Of AZ31-Ce Magnesium Alloy Prepared By Multipass Solid-phase Synthesis

In recent years,the demand for magnesium alloys has increased with the development of science and technology.Magnesium alloys have been extensively applied to the aerospace,traffic,military and 3C electronic industry.Magnesium alloys have low performance.Magnesium alloys with RE addition can improve the microstructure,increase the mechanical properties of the alloys at room and high temperature and enhance the corrosion resistance.In the production process of magnesium alloys,it produces a lot of chips or scraps.In the process of solid-phase synthesis,chips or scraps are not remelted.Compared with the melting process,with the addition of alloying elements,it not only avoids some shortcomings such as oxidation,burning loss,segregation,and difficulty in adding elements in the process of melting,but also saves resources and reduces environmental pollution.In this paper,AZ31-2.5 wt-% Ce magnesium alloy,which was composed of AZ31 magnesium alloy chips and Mg-30 wt-% Ce intermediate alloy chips,was prepared by solid-phase synthesis.The alloy was characterized by optional microscopy,scanning electron microscopy,energy-dispersive X-ray spectrometry and an electronic universal strength tester.The microstructure,mechanical properties and fracture mechanism of AZ31-Ce magnesium alloy prepared by solid-phase synthesis were studied.The deformation mechanism of Mg-Ce chips was also discussed.Compared with as-cast and as-extrusion AZ31 magnesium alloys,the corrosion resistance and compression performance of AZ31-Ce magnesium alloy after multipass extrusion were discussed.The effects of extrusion passes on the microstructure and mechanical properties of AZ31-Ce magnesium alloy were studied.With an increase in the extrusion passes,the mechanical properties of the alloy gradually increase.While the extrusion pass is 5th pass,the tensile strength and elongation reach 311 MPa and 9.83 %,respectively.The bonding between Mg-Ce intermediate alloy chips and AZ31 magnesium alloy chips constantly increases and the fracture mechanism tends to ductile fracture.Mg-Ce chips are constantly crushed and deformed,and finally exhibit a fine granulated shape.Mg-Ce intermediate alloy chips exhibit a medium-scale granulated,fiber-like and fine spherical shape,respectively,and meanwhile,the Al4 Ce layer is formed around the Mg-Ce chip.The thickness of Al4 Ce layer constantly increases.The corrosion resistance of AZ31-Ce magnesium alloy after five passes of solid-phase synthesis was investigated.The macroscopic and microscopic corrosion morphologies and corrosion rate of AZ31-Ce magnesium alloy in 3.5 wt-% Na Cl solution were characterized by mass loss corrosion test.The corrosion resistance of AZ31-Ce magnesium alloy was evaluated by comparing with as-cast and as-extrusion AZ31 magnesium alloy.After the corrosion of 64 h,the corrosion resistance of as-cast AZ31 magnesium alloy is the best,the second is as-extrusion AZ31 magnesium alloy,and the corrosion resistance of AZ31-Ce magnesium alloy is the worst.The main reason for the unimproved corrosion resistance of AZ31-Ce magnesium alloy is that the content of Al4 Ce in the alloy increases when 2.5 wt-% Ce is added to AZ31-Ce magnesium alloy.Too much Al4 Ce phase results in the increasing of the partial polymerization,and then the corrosion resistance is poor.The compression performance of AZ31-Ce magnesium alloy after five passes of solid-phase synthesis was investigated.Compression test was carried out at different temperature on WDW-200 compressor.Microstructure,macroscopic and microscopic morphologies were observed.The compression performance of AZ31-Ce magnesium alloy was evaluated by comparing with as-cast and as-extrusion AZ31 magnesium alloy.At room temperature,the specimens fracture.The fracture mechanism of as-cast and as-extrusion AZ31 magnesium alloy is brittle fracture.The fracture mechanism of AZ31-Ce magnesium alloy is ductile-brittle mixed fracture mode and the alloy exhibits good plasticity.The specimens are squashed at high temperature,and exhibit the shape of a drum.At 350 ?,the deformation of as-cast AZ31 magnesium alloy,as-extrusion AZ31 magnesium alloy and AZ31-Ce magnesium alloy is 40 %,43.33 % and 48 %,respectively.