工学]材料科学基础英文版

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1、Chapter1AtomicStructureandInteratomicBonding11.IntroductionSomeoftheimportantpropertiesofsolidmaterialsdependongeometricalatomicarrangements.Thepropertiesofmaterialsarecontrollableandcanbetailoredtotheneedsofagivenapplicationbycontrollingtheirstructureandcomposition.Wecanexaminean

2、ddescribethestructureofmaterialsatdifferentlevels.2Subatomiclevel:Electronicstructureofindividualatomsthatdefinesinteractionamongatoms(interatomicbonding).Atomiclevel:Arrangementofatomsinmaterials.Nanostructure:thestructureofmaterialatalength-scaleof100nm.Microstructure:thestruct

3、ureofmaterialatalength-scaleof~10to1000nm.Macrostructure:thestructureofamaterialatamacroscopiclevelwherethelength-scaleis~1000,000nm.3Length-scalesAngstrom=1Å=1/10,000,000,000meter=10-10mNanometer=10nm=1/1,000,000,000meter=10-9mMicrometer=1μm=1/1,000,000meter=10-6mMillimeter=1mm=

4、1/1,000meter=10-3mInteratomicdistance~afewÅAhumanhairis~50μmElongatedbumpsthatmakeupthedatatrackonCDare~0.5μmwide,minimum0.83μmlong,and125nmhigh45Thismicrograph,whichrepresentsthesurfaceofagoldspecimen,wastakenwithaatomicforcemicroscope(AFM).Individualatomsforthis(111)crystallogra

5、phicsurfaceplaneareresolved.6Amorphous:lackalong-rangeorderingofatomsorions.Crystalline:exhibitperiodicarrangementsofatomsorions.Thelong-rangeatomicorderisintheformofatomsorionsarrangedinathreedimensionalpatternthatrepeatsovermuchlargerdistances(from~>100nmtouptofewcm).Short-range

6、atomicarrangements:theatomsofionsshowaparticularorderonlyoverrelativelyshortdistances.72.AtomicStructureAtomicstructureinfluenceshowatomsarebondedtogether.Anunderstandingofthishelpscategorizematerialasmetals,semiconductors,ceramics,orpolymers.Atoms=nucleus(protonsandneutrons)+elec

7、trons8Charges:Electronsandprotonshavenegativeandpositivechargesofthesamemagnitude,1.6×10-19Coulombs.Neutronsareelectricallyneutral.Masses:ProtonsandNeutronshavethesamemass,1.67×10-27kg.Massofanelectronismuchsmaller,9.11×10-31kgandcanbeneglectedincalculationofatomicmass.Theatomicma

8、ss(A)=massofprotons+massofneutron