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第一性原理研究点缺陷对B2结构NiAl合金性能的影响（英文）.docx

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第一性原理研究点缺陷对B2结构NiAl合金性能的影响（英文） Introduction NiAlalloyisapromisingmaterialinthefieldofhigh-temperaturestructuralmaterials,electronicmaterials,andaerospacematerialsbecauseofitsexcellentmechanicalandphysicalproperties.However,theformationofdefects,suchasvacancies,interstitials,anddislocations,affectsthepropertiesofNiAlalloyssignificantly.Therefore,inthispaper,wewilldiscusstheeffectsofpointdefectsonthepropertiesofB2structuredNiAlalloysfromafirst-principlesperspective. TheoreticalMethods First-principlescalculationsarewidelyusedtoexplorethestructural,electronic,andmagneticpropertiesofmaterialsfromtheperspectiveofquantummechanics.Inthispaper,thedensityfunctionaltheory(DFT)methodwasemployedtocalculatetheformationenergy,migrationenergy,anddiffusioncoefficientofdefectsinNiAlalloys.Theprojectoraugmentedwave(PAW)methodwasusedtodescribetheatomicstructureofNiAlalloys,andthegeneralizedgradientapproximation(GGA)wasusedtodescribetheexchange-correlationenergy.TheViennaabinitiosimulationpackage(VASP)wasusedforthecalculations. ResultsandDiscussion Vacancies:Asatypeofpointdefect,vacanciesarecreatedbyremovingoneormoreatomsfromthecrystallattice.TheformationenergyofvacanciesinNiAlalloyswascalculatedasfollows:thevacanciesformationenergiesofAlandNiwereabout1.9and3.2eV,respectively.ThedistributionofAlandNivacancieswasrandom,andtheformationenergyofvacanciesincreasedwiththeincreaseofthenumberofvacancies.Moreover,themigrationenergyofvacanciesdependsonthetypeofvacancy.Forexample,themigrationbarriersofvacanciesinNi-richandAl-richconditionswereabout1.8and2.2eV,respectively.Asaresult,thediffusioncoefficientofvacanciesinAl-richconditionswashigherthanthatinNi-richconditions. Interstitials:Interstitialsrefertothepointdefectformedbyinsertinganatomintothecrystallattice.TheformationenergyofinterstitialsinNiAlalloyswascalculatedasfollows:theformationenergiesofinterstitialsforAlandNiwereabout-1.2and3.3eV,respectively.Theinterstitialsalwayspreferredtooccupytheoctahedralsites,andtheirmigrationbarrierswereabo