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1、内蒙古科技大学硕士学位论文AbstractWiththerapiddevelopmentandhighrequirementsoferospace,automobile,electronicscienceandtechnology,magnesiumalloyhasbeenwidelyused.Inordertomakebetterapplicationinvariousfields,magnesiumalloyneedsfurthertoimprovethemechanicalpropertiesandmaterial
2、sprocessingperformancewithtissuehomogenizationandgrainrefinement,thisapplicati-onofmagnesiumalloyinthefieldofmodernscienceandtechnologydevelopmenthastheprofoundsignificance.Inthispaper,usingthesemi-solidelectromagneticstirringequipmenttopreparetheMg-Gdalloycastin
3、gswiththedifferentcontentofGd,suchas5.5%,10%and15%,anditsdiameteris90mm,highis160mm,inthesolidificationprocessofmagnesiumalloymeltingliquid,toapplyingelectromagneticstirringforcewiththevoltagelessthan200Vandthefrequencylessthan20Hz.Usingmetallographicmicroscope,s
4、canningelectronmicroscopy,X-raydiffractionandmechanicalperformancetesttotsetmagnesiumalloyascaststructuremorphology,grainsizeandhardness,andresearchcontentofrareearthelementGd,electromagneticstirringprocessonthemicrostructureandhardnessofmagnesiumalloyarestudied.
5、Itwasfoundthatinmagnesiumalloysmeltingprocess,theaddingofGdcanmakethegrainrefinementofmagnesiumalloy,andwiththeincreaseofGdcontent,grainsizewillbereduced,withtheGdcontentincreasedfrom5.5%to10%and15%,thegrainsizerisesfrom340μmto282μmand268μm,thehardnessrisesfrom28
6、HRBriseto42HRBand48HRB.Preparationofmagnesiumalloyelectromagneticstirringprocesscanmaketheorganizationofthealloygrainrefine,reducethesolutesegregationinGdinthematrix,a
reductioninthenumberofinclusionsandthemorphologydifferenceofeachpartofthe
ingotcasting,atthesam
7、etime,italsocanimprovethedegreeofsupersaturationofthe
secondphaseMg5Gd,improvethehardnessofmagnesiumalloy.Thevoltageislessthan
200V,lessthan20Hzfrequencyrange,raisethevoltageandfrequencyvaluescangetII内蒙古科技大学硕士学位论文bettereffectofelectromagneticstirring,suchasthefre
8、quencyis8Hz,thevoltageisfrom80Vto120V,topreparetheMg-GdalloywiththeGdcontentis11%,thehardnessis62HRBand74HRB;Whenthecoolingrateincreasedby5.5℃/minto12℃/min,the
