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1、内蒙古科技大学硕士学位论文AbstractWiththerapiddevelopmentandhighrequirementsoferospace,automobile,electronicscienceandtechnology,magnesiumalloyhasbeenwidelyused.Inordertomakebetterapplicationinvariousfields,magnesiumalloyneedsfurthertoimprovethemechanicalpropertiesandmaterialsprocessingperfor
2、mancewithtissuehomogenizationandgrainrefinement,thisapplicati-onofmagnesiumalloyinthefieldofmodernscienceandtechnologydevelopmenthastheprofoundsignificance.Inthispaper,usingthesemi-solidelectromagneticstirringequipmenttopreparetheMg-GdalloycastingswiththedifferentcontentofGd,such
3、as5.5%,10%and15%,anditsdiameteris90mm,highis160mm,inthesolidificationprocessofmagnesiumalloymeltingliquid,toapplyingelectromagneticstirringforcewiththevoltagelessthan200Vandthefrequencylessthan20Hz.Usingmetallographicmicroscope,scanningelectronmicroscopy,X-raydiffractionandmechan
4、icalperformancetesttotsetmagnesiumalloyascaststructuremorphology,grainsizeandhardness,andresearchcontentofrareearthelementGd,electromagneticstirringprocessonthemicrostructureandhardnessofmagnesiumalloyarestudied.Itwasfoundthatinmagnesiumalloysmeltingprocess,theaddingofGdcanmaketh
5、egrainrefinementofmagnesiumalloy,andwiththeincreaseofGdcontent,grainsizewillbereduced,withtheGdcontentincreasedfrom5.5%to10%and15%,thegrainsizerisesfrom340μmto282μmand268μm,thehardnessrisesfrom28HRBriseto42HRBand48HRB.Preparationofmagnesiumalloyelectromagneticstirringprocesscanma
6、ketheorganizationofthealloygrainrefine,reducethesolutesegregationinGdinthematrix,areductioninthenumberofinclusionsandthemorphologydifferenceofeachpartoftheingotcasting,atthesametime,italsocanimprovethedegreeofsupersaturationofthesecondphaseMg5Gd,improvethehardnessofmagnesiumalloy
7、.Thevoltageislessthan200V,lessthan20Hzfrequencyrange,raisethevoltageandfrequencyvaluescangetII内蒙古科技大学硕士学位论文bettereffectofelectromagneticstirring,suchasthefrequencyis8Hz,thevoltageisfrom80Vto120V,topreparetheMg-GdalloywiththeGdcontentis11%,thehardnessis62HRBand74HRB;Whenthecooling
8、rateincreasedby5.5℃/minto12℃/min,thefina
