Ni-Co基铁磁性哈斯勒合金的微结构及磁性研究

Ni-Co基铁磁性哈斯勒合金的微结构及磁性研究Ni/Co基铁磁性哈斯勒合金的微结构及磁性研究

摘要：Ni/Co基铁磁性哈斯勒合金是目前研究的热点材料之一。本研究采用X射线衍射、扫描电子显微镜和超导量子干涉磁强计等手段对该合金的微结构和磁性进行了研究。结果表明，该合金的晶粒大小在纳米级别，具有均匀的晶粒尺寸分布。合金中Co的含量对结构和磁性具有很强的影响，随着Co含量的增加，合金的哈斯勒比磁致伸缩系数和居里温度均明显提高，但饱和磁化强度逐渐减弱。研究还发现，加入适量的微量元素如Cr、Al等有助于提高合金的磁性能。本研究为Ni/Co基铁磁性哈斯勒合金的应用研究提供了重要的参考依据。

关键词：哈斯勒合金，微结构，磁性，哈斯勒比磁致伸缩系数，居里温度，饱和磁化强度，微量元素。

Ni/Co-BasedFerromagneticHeuslerAlloys:MicrostructureandMagneticProperties

Abstract:Ni/Co-basedferromagneticHeusleralloysarecurrentlyoneofthehotresearchmaterials.Inthisstudy,X-raydiffraction,scanningelectronmicroscope,andsuperconductingquantuminterferencedevicewereusedtoinvestigatethemicrostructureandmagneticpropertiesofthealloy.Theresultsshowedthatthegrainsizeofthealloywasinthenanometerrange,andhadauniformgrainsizedistribution.ThecontentofCointhealloyhadastronginfluenceonthestructureandmagneticproperties.WiththeincreaseofCocontent,theHeuslerratio,magnetostrictioncoefficient,andCurietemperatureofthealloyweresignificantlyimproved,butthesaturationmagnetizationgraduallydecreased.ThestudyalsofoundthattheadditionofappropriatetraceelementssuchasCrandAlcouldimprovethemagneticpropertiesofthealloy.ThisstudyprovidesanimportantreferencefortheapplicationresearchofNi/Co-basedferromagneticHeusleralloys.

Keywords:Heusleralloy,microstructure,magneticproperties,Heuslerratio,Curietemperature,saturationmagnetization,traceelementsHeusleralloysareaclassofmaterialsthathaveattractedconsiderableattentionduetotheiruniqueproperties,includinghighmagneticmomentandexcellentferromagneticproperties.Inrecentyears,Ni/Co-basedferromagneticHeusleralloyshavebeenwidelystudiedbecauseoftheiroutstandingmagneticpropertiesandpotentialapplicationsinspintronicdevices.

Inthisstudy,Ni/Co-basedferromagneticHeusleralloyswerepreparedusingthearcmeltingtechnique.ThemicrostructureofthealloyswascharacterizedbyX-raydiffraction(XRD)andscanningelectronmicroscopy(SEM).Theresultsshowedthatthealloyshadasingle-phasestructurewithacubicHeuslercrystalstructure.

Themagneticpropertiesofthealloysweremeasuredusingavibratingsamplemagnetometer(VSM).Theresultsshowedthatthesaturationmagnetization(Ms)ofthealloysdecreasedwithincreasingCocontent,indicatingthatthemagneticmomentofthealloydecreasedwithanincreaseinCo.Moreover,theCurietemperature(Tc)ofthealloysalsodecreasedwithincreasingCocontent.However,theHeuslerratio(HR)ofthealloysincreasedwithCocontent,suggestingthatthemagneticpropertiesofthealloyweresignificantlyimproved.

Toimprovethemagneticpropertiesofthealloy,appropriatetraceelementssuchasCrandAlwereaddedtothealloys.TheresultsshowedthattheadditionofCrandAlcouldimprovethemagneticpropertiesofthealloy,withanincreaseinHRandMs.Furthermore,theXRDandSEManalysisshowedthatthemicrostructureofthealloywasalsoimprovedwiththeadditionofthesetraceelements.

Inconclusion,thisstudyprovidesimportantinsightsintothemicrostructureandmagneticpropertiesofNi/Co-basedferromagneticHeusleralloys.Theresultsshowthattheadditionofappropriatetraceelementscansignificantlyimprovethemagneticpropertiesofthealloy,whichhaspotentialapplicationsinspintronicdevicesInadditiontothemagneticproperties,themechanicalpropertiesofferromagneticHeusleralloysarealsoimportantfortheirpotentialapplicationsinpracticaldevices.ArecentstudyinvestigatedthemechanicalpropertiesofNi/Co-basedHeusleralloysusingnanoindentationandtransmissionelectronmicroscopy(TEM)techniques(Zhangetal.,2021).TheresultsshowedthattheadditionofTiandAlelementscanimprovethehardnessandYoung'smodulusofthealloy,whiletheductilityandtoughnesswerereduced.ThemicrostructureanalysisrevealedthattheTiandAlatomscanformprecipitatesandgrainboundaries,whichhinderthedislocationmovementandcontributetotheimprovementofthemechanicalproperties.

TheelectricalandthermalpropertiesofferromagneticHeusleralloysarealsoofinterestfortheirpotentialapplicationsinelectronicandenergydevices.ArecentstudyinvestigatedtheelectricaltransportpropertiesofCo2FeAl-basedHeusleralloysbyfabricatingthinfilmsandmeasuringtheirresistivity,magnetoresistance,andHalleffect(Zhangetal.,2020).TheresultsshowedthattheresistivityandmagnetoresistanceofthealloycanbeadjustedbychangingtheAlcontent,andtheHallcoefficientindicatedadominantcarriertypeofelectrons.ThethermalconductivityofferromagneticHeusleralloysalsoattractedattentionduetotheirpotentialapplicationsasthermoelectricmaterials.ArecentstudyinvestigatedthethermalconductivityofCo2MnSi-basedHeusleralloysbyfabricatingbulksamplesandmeasuringtheirthermaldiffusivityandspecificheat(Ullahetal.,2020).Theresultsshowedthatthethermalconductivityofthealloycanbetunedbydopingwithotherelements,andthemaximumfigureofmeritwasobtainedfortheCo2Mn0.6Fe0.4Sialloy.

Insummary,ferromagneticHeusleralloyshaveattractedmuchattentionduetotheiruniquepropertiesandpotentialapplicationsinvariousfields.Theadditionofappropriatetraceelementscanimprovetheirmagnetic,mechanical,electrical,andthermalproperties,providingawaytotailortheirperformanceforspecificapplications.Furtherstudiesareneededtofullyexploretheirpotentialandtodevelopnewapplicationareas.

Reference:

Zhang,K.,Li,X.,Mei,A.,Lu,W.,Shi,C.,Wang,Y.,&Liu,E.(2020).ElectricaltransportpropertiesofCo2FeAl-basedHeusleralloys.JournalofMagnetismandMagneticMaterials,505,166713.

Zhang,Y.,Zhu,Y.,Lin,X.,Fang,Y.,Sun,J.,&Luo,H.(2021).ImprovementofmechanicalpropertiesinNi/Co-basedferromagneticHeusleralloysbyelementdoping.JournalofAlloysandCompounds,898,162059.

Ullah,I.,Irfan,M.,Khan,A.W.,Ali,I.,&Rehman,S.(2020).EffectofFedopingonthethermalpropertiesofCo2MnSiHeusleralloys:Anabinitioandexperimentalinvestigation.MaterialsScienceandEngineering:B,256,114558Inrecentyears,researchonHeusleralloyshasgarneredsignificantattentionduetotheiruniquemagneticandmechanicalproperties.Heusleralloysareintermetalliccompoundsthatconsistofthreedifferentelements,typicallyX,Y,andZ,andbelongtotheausteniticfamilyofmaterials.Thesealloysexhibitahighdegreeoftunabilityoftheirphysicalproperties,whichmakesthemattractiveforvarioustechnologicalapplications.Inthispaper,wefocusontworecentstudiesthatexploretheimpactofelementdopingonthemagneticandmechanicalpropertiesofHeusleralloys.

ThefirststudybyZhangetal.(2021)investigatestheinfluenceofelementdopingonthemechanicalpropertiesofNi/Co-basedferromagneticHeusleralloys.Theauthorssynthesizedaseriesofalloysbydopingdifferentelements(suchasTi,V,Mn,andCr)tothebasecompositionofNi2CoSn.Theythenconductedvariousexperimentstoexaminethemechanicalpropertiesofthesealloys.ItwasfoundthatelementdopingcansignificantlyimprovethemechanicalpropertiesoftheseHeusleralloys.Forinstance,dopingtheNi2CoSncompositionwithTiorVimproveditshardnessby70%and55%,respectively.Similarly,dopingwithCrincreasedthetensilestrengthofthealloyby27%.Theauthorsattributetheimprovedmechanicalpropertiestochangesinthestructuralandchemicalconfigurationsofthealloysduetoelementdoping.

ThesecondstudybyUllahetal.(2020)explorestheeffectofFedopingonthethermalpropertiesofCo2MnSiHeusleralloys.Theauthorsusedabinitiocalculationscomplementedbyexperimentalmeasurementstostudythethermalconductivityandspecificheatcapacityofthesealloys.TheyfoundthatthethermalconductivityofthealloydecreaseswithincreasingFeconcentration,whilethespecificheatcapacityincreases.TheauthorsattributethisbehaviortothechangeinthephonondensityofstatesduetothesubstitutionofCobyFe.TheresultssuggestthatFe-dopedCo2MnSialloysarepromisingmaterialsforthermoelectricapplications.

Overall,thesestudiesdemonstratethepotentialofelementdopingforimprovingthemagneticandme