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Fundamentalsmaterialsscienceandengineering材料科学与工程基础SchoolofmaterialsScienceandEngineering材料科学与工程学院CHAPTER1/IntroductionAfamiliaritemthatisfabricatedfromthreedifferentmaterialtypesisthebeveragecontainer.

Beveragesaremarketedinaluminum(metal)cans,glass(ceramic)bottlesplastic(polymer)bottles金属陶瓷聚合物1.1HistoricalPerspectiveHistorically,thedevelopmentandadvancementofsocietieshavebeenintimatelytiedtothemembers’abilitytoproduceandmanipulatematerialstofilltheirneeds.Infact,earlycivilizationshavebeendesignatedbytheleveloftheirmaterialsdevelopmentStoneAge,BronzeAge,IronAge,ElectricAge,InformationAgeActually,ItisamaterialsphylogenythathumanhistoryevolvedStoneBronzeIron1.2MaterialsScienceAndEngineeringmaterialssciencerelationshipsbetweenthestructuresandpropertiesinvestigatingmaterialsengineeringdesigningorengineeringthestructureofamaterialtoproduceapredeterminedsetofproperties.加工过程组织结构性质使用性能Composition成分‘‘Structure’’ofamaterialusuallyrelatestothearrangementofitsinternalcomponents.Subatomicstructure原子内的atomiclevel原子间的microscopicmacroscopic‘‘property’’:allmaterialsareexposedtoexternalstimulithatevokesometypeofresponse.SixdifferentimportantpropertiesMechanicalproperties

力学性能Electricalproperties电性能Thermalbehavior热性能Magneticproperties磁性能Opticalproperties光性能Deteriorativecharacteristics老化特性微观的巨观的FIGURE1.2Photographshowingthelighttransmittanceofthreealuminumoxidespecimens.Fromlefttoright:singlecrystalmaterial(sapphire),whichistransparent;apolycrystallineandfullydense(nonporous)material,whichistranslucent;andapolycrystallinematerialthatcontainsapproximately5%porosity,whichisopaque.Twootherimportantcomponentsareprocessing

andperformance.Withregardtotherelationshipsofthesefourcomponents,structureofamaterialwilldependonhowitisprocessed.Furthermore,amaterial’sperformance

willbeafunctionofitsproperties.Thus,theinterrelationshipbetweenprocessing,structure,properties,andperformanceislinear.蓝宝石无孔的多孔的1.3WhyStudyMaterialsScienceAndEngineering?amaterialsproblemisoneofselectingtherightmaterialfromthemanythousandsthatareavailable.designproblemwilldealwithmechanical,civil,chemical,orelectricalFirstofall,thein-serviceconditionsmustbecharacterized,forthesewilldictatethepropertiesrequiredofthematerial.Asecondselectionconsiderationisanydeterioration

ofmaterialpropertiesthatmayoccurduringserviceoperation.Finally,probablytheoverridingconsiderationisthatofeconomics.机械民用化学电合理选材退化1.4ClassificationOfMaterialsSolidmaterialshavebeenconvenientlygroupedintothreebasicclassifications:metals,ceramics,andpolymers.Thisschemeisbasedprimarilyonchemicalmakeupandatomicstructure,andmostmaterialsfallintoonedistinctgroupingoranother,althoughtherearesomeintermediates.Inaddition,therearethreeothergroupsofimportantengineeringmaterials—composites,semiconductors,andbiomaterials.复合材料生物材料半导体材料METALSMetallicmaterialsarenormallycombinationsofmetallicelements.Theyhavelargenumbersofnonlocalizedelectrons;thatis,theseelectronsarenotboundtoparticularatoms.Manypropertiesofmetalsaredirectlyattributabletotheseelectrons.Metalsareextremelygoodconductorsofelectricity

andheatandarenottransparenttovisiblelight;apolishedmetalsurfacehasalustrousappearance.Furthermore,metalsarequitestrong,yetdeformable,whichaccountsfortheirextensiveuseinstructuralapplications.有光泽的CERAMICSCeramicsarecompoundsbetweenmetallicandnonmetallicelements;theyaremostfrequentlyoxides,nitrides,andcarbides.Thewiderangeofmaterialsthatfallswithinthisclassificationincludesceramicsthatarecomposedofclayminerals,cement,andglass.Thesematerialsaretypicallyinsulativetothepassageofelectricityandheat,andaremoreresistanttohightemperaturesandharshenvironmentsthanmetalsandpolymers.Withregardtomechanicalbehavior,ceramicsarehardbutverybrittle.粘土矿水泥绝缘的恶化环境POLYMERSPolymersincludethefamiliarplasticandrubbermaterials.Manyofthemareorganiccompoundsthatarechemicallybasedoncarbon,hydrogen,andothernonmetallicelements;furthermore,theyhaveverylargemolecularstructures.Thesematerialstypicallyhavelowdensitiesandmaybeextremelyflexible.柔韧的COMPOSITESAnumberofcompositematerialshavebeenengineeredthatconsistofmorethanonematerialtype.Fiberglassisafamiliarexample,inwhichglassfibersareembeddedwithinapolymericmaterial.Acompositeisdesignedtodisplayacombinationofthebestcharacteristicsofeachofthecomponentmaterials.Fiberglassacquiresstrengthfromtheglassandflexibilityfromthepolymer.Manyoftherecentmaterialdevelopmentshaveinvolvedcompositematerials.SEMICONDUCTORSSemiconductorshaveelectricalpropertiesthatareintermediatebetweentheelectricalconductorsandinsulators.Furthermore,theelectricalcharacteristicsofthesematerialsareextremelysensitivetothepresenceofminuteconcentrationsofimpurityatoms,whichconcentrationsmaybecontrolledoververysmallspatialregions.Thesemiconductorshavemadepossibletheadventofintegratedcircuitrythathastotallyrevolutionizedtheelectronicsandcomputerindustries(nottomentionourlives)overthepasttwodecades.BIOMATERIALSBiomaterialsareemployedincomponentsimplantedintothehumanbodyforreplacementofdiseasedordamagedbodyparts.Thesematerialsmustnotproducetoxicsubstancesandmustbecompatiblewithbodytissues(i.e.,mustnotcauseadversebiologicalreactions).Alloftheabovematerials—metals,ceramics,polymers,composites,andsemiconductors—maybeusedasbiomaterials.1.5AdvancedMaterialsMaterialsthatareutilizedinhigh-technologyapplicationsaresometimestermedadvancedmaterials.VCRs,CDplayers,etc.,computers,fiberopticsystems,spacecraft,aircraft,andmilitaryrocketry.FunctionalmaterialsForexampls:shape