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1、MaterialsScience（材料科学）：involvesinvestigatingtherelationshipsthatexistbetweenthestructuresandpropertiesofmaterials(研究结构与性能之间的关系)MaterialsEngineering（材料工程）:designingorengineeringthestructureofamaterialtoproduceapredeterminedsetofproperties,basedonthesestructure-propertycorrelations.(设计材料结构以产生预定的
2、性能)Macroscopic(宏观)Microscopic(微观)Structure(结构)Property(性能)：mechanical(机械性),electrical（电性）,thermal（热性）,magnetic（磁性）,optical（光学性）,anddeteriorative（失效性）ProcessingandPerformance（加工和性能）ClassificationofMaterials（材料的分类）：Basic:metals,ceramics,polymersEngineeringmaterials:composites,semiconductors,biom
3、aterialsBasicEngineeringmaterials2.2Basicconcepts(基本概念)Crystal(晶体)Itissolid.Thearrangementofatomsinthecrystalisperiodic.Incrystallinestructure,theatomsdisplaybothshort-rangeandlong-rangeorder（原子显示短程和长程有序）.(metals,manyceramics,andevensomepolymers).CharacteristicofCrystals晶体的特性1.Geometricalshape
4、几何形状2.Fixedmeltingpointandboilingpoint固定的熔点和沸点3.Anisotropy(各向异性）：质点在晶格各个方向排列的距离不同而形成Lattice（点阵,晶格）Aninfinitearrayofpointsinspace,inwhicheachpointhasidenticalsurroundingstoallothers(晶体点阵是晶体粒子所在位置的点在空间的排列).Athreedimensionalarrayofpointscoincidingwithatompositions(oratomicspherecenter).一个三维数组与原子的
5、位置（或原子球体中心）相吻合点。CrystalStructure（晶体结构）Itcanbedescribedbyassociatingeachlatticepointwithagroupofatoms.晶体结构＝空间点阵＋结构基元(原子,分子或集团)2.3Unitcells(单胞)Atomichardspheremodel.原子硬球模型Unitcells(单胞)：Thesmallestcomponentofcrystal,whichwhenstackedtogetherwithpuretranslationalrepetitionreproducesthewholecrystal(
6、晶格中最小的结构重复单位）UnitCellDimensions(单胞参数)a,bandcaretheunitcelledgelengths.α,β,andγ,aretheanglesαbetweenbandcβbetweencandaγbetweenaandb2.4CrystalStructures(晶体结构)Threesimplecrystalstructuresare: Face-centeredcubic(面心立方）--FCC Body-centeredcubic（体心立方）--BCCHexagonal-close-packed（六方密堆）--HCPFCCcrystals
7、tructurehasaunitcellofcubicgeometry,withatomslocatedateachofthecornersandcentersofallthecubeface.除8个顶点外，每个面心上有一个阵点.a=b=c,α=β=γ=90oeg:Cu,Al,Au,AgForFCCstructure,atotaloffouratomsareassignedtoagivenunitcell(对FCC结构来说,每个单胞有4个完整的原子)Cornerand
