Study On The Microstructure And Mechanical Properites Of Mg-Gd-Y Magnesium Alloy By Equal Channel Angular Pressing

Equal channel Angular presssing(ECAP) was used to refine themicrostructure of Mg-10Gd-3Y-0.5Zr(GW103) magnesium alloy from390℃to450℃with the sample size of12mmx12mmx90mm.Mg-4Gd-0.5Zr(GW4K) magnesium alloy was processed by ECAP at390℃from1to4passes. Two-step-ECAP process was performed to refine theGW4K magnesium alloy. The microstructure was examined byOM、SEM、XRD, and the texture was examined by EBSD. Evolution ofmicrostructure and meachanical properties of GW103and GW4k processedby ECAP was investigated.During the process of GW103K magnesium alloy processed by ECAPfrom1to4passes at450℃. With the increase of pass number, the grain wasrefined gradually. There was no precipitate during ECAP due to highextrusion temperature. The precipitation way was vertificated as dynamicprecipitation through the comparative experiment. The ditribution ofrecrystallization particles and precipitates was synchronous, dynamicrecrystallization performed preferentialy near the second phase particles,which has typical character of particle stimulate nuclear(PSN). Within thefirst three passes, both the Yield strengh and elongation increased alongwith the process of grain refinement and dynamic precipitation. After4passes, dynamic recrystallization occurred completely, the grain would notbe refined with the increase of strain. During the process of GW4kmagnesium alloy processed by ECAP from1to4passes at390℃, with theincreas of pass number, the grain was refined gradually and Yield strengh increased.For the reverse Hall-Petch relationship phenomeon in AZ31magnesium alloy processed by ECAP, this was conformed in our studythrough the comparative experiment. The relationship between grainsize,texture and mechanical properties in rare earth magnesium alloyprocessed by ECAP was investigated in our study. It was shown that for rareearth magnesium alloy, the Yield strengh increased along with the process ofgrain refinement, which was accord with Hall-Petch relationship.