zr對(duì)mg2.8nd0.35zn合金高溫性能影響的研究

1、工程碩士學(xué)位論文y79磊乏6SZr對(duì)Mg28Nd035Zn合金高溫性能影響的研究劉洪匯哈爾濱理工大學(xué)：2005年3月里至鎏翌三奎蘭王耋塑土耋竺量耋THEEFFECTSoFZroNHIGHTEMPERATUREPROPERTYOFTHEMg28Nd—O35ZnMAGNESIUMALLoYAbstractE舭ctsofZronthemicrostructureandmechanicalpropertiesatelevatedtemperat

2、urewereinvestigatedbymeansofopticalmicroscopeandscanningelectronicmicroscope(SEM)ProcessofsettlingdownofZrparticlesinmeltwascalculatedbyusingsecondlawTheexperimentalresultsshowbothgrainsizeandgrainmorphologyofMg—Nd。Znall

3、oysaresignificantlyaffectedbyadditionofZrMeangrainsizeatthecentreofsamplesisabout1200llmwhennoZradditioniSmadeGrainsizedecreasesdramaticallyto520lamwhen02％ZradditionandfurtherdecreasewiththeincreasedZradditionGrainsizeiS

4、9812mwhenZradditionreachesO6％thendecreasesslightlyGrainsizedecreasesonly5UmwhenZradditionvariesfrom06％to12％ThismeansthatthereiSacriticalvalueforZradditionuntil12％afterwhichthegrainsizechangesliuleEffectsofelementsongrain

5、sizeofMgalloyswerequantitativelyestimatedbyusingGrainRestrictionFactorTheresultsshowthataffectofZriSthemostimportantBothtensilestrengthandelongationofMgNdZnalloysatelevatedtemperaturewereincreasedwiththeincreasingofZradd

6、itionSEMobservationoffractographfor6％ZradditionshowsthatplasticpitsandtearingridgesareuniformlydistributedThisindicatesMg—Nd—ZnalloysrefinedbyZrhasahighductilityUnder75and100MPaat250“C，thecreepresistanceiSimprovedwiththe

7、increasedZradditionThecreeprateisthelowestwhen12％ZrwasaddedThemainfactoraffectingsettingofZrparticleisitssizebasedoncalculatingforZrparticlesettingdowninmeltSettingdistancehaslittlechangewhenthesizeofZrparticleis1essthan