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1、2.2Crystalstructuresofmetals2.2.1CrystalstructuresofpuremetalsMetalatomsarecombinedbytheinteractionbetweenthepositiveionsandthefreeelectrons,namedmetallicbonds.Metalstendtoarraytightly.价电子云正离子MetallicbondsMetalshavegoodthermalconductivity,electricconductivity,ductilityandmetallicbrightness.Thecomm
2、oncrystallatticetypeofpuremetalsarebodycenteredcubic(bcc),facecenteredcubic(fcc),andclose-packedhexagonal.二、金属的晶体结构1、纯金属的晶体结构金属原子是通过正离子与自由电子的相互作用而结合的，称为金属键。金属原子趋向于紧密排列。价电子云正离子金属键示意图具有良好的导热性、导电性、延展性及金属光泽。常见纯金属的晶格类型有体心立方(bcc)、面心立方(fcc)和密排六方(hcp)晶格。⑴BodycenteredcubiccrystallatticeBodycenteredcubiccry
3、stallatticeParametersforbodycenteredcubiccrystallatticeBodycenteredcubiccrystallatticeAtomicity:2Coordinationnumber:8Tightness:0.68Frequentmetals:-Fe,Cr,W,Mo,V,Nb,etc.Crystallatticeconstants:a(a=b=c)Atomradius:体心立方晶格原子个数：2配位数：8致密度：0.68常见金属：-Fe、Cr、W、Mo、V、Nb等晶格常数：a(a=b=c)原子半径：⑵Facecenteredcubiccry
4、stallatticeFacedcenteredcubiccrystallatticeParametersforfacecenteredcubiccrystallatticea42r=：Atomradius:Atomicity:4Coordinatenumber:12Tightness:0.74Frequentmetals:-Fe,Ni,Al,Cu,Pb,Au,etc.Crystallatticeconstant:aFacecenteredcubiccrystallatticea42r=：原子半径原子个数：4配位数：12致密度：0.74常见金属：-Fe、Ni、Al、Cu、Pb、Au等晶
5、格常数：a面心立方晶格⑶Closed-packedhexagonalcrystallatticeParametersforclosed-packedhexagonalcrystallatticea21r=：Atomradius:Atomicity:6Coordinatenumber:12Tightness:0.74Frequentmetals:Mg,Zn,Be,Cd,etc.Crystallatticeconstant:sidelengthofbasefaceaandc,c/a=1.633Closed-packedhexagonalcrystallatticea21r=：原子半径原子个数：
6、6配位数：12致密度：0.74常见金属：Mg、Zn、Be、Cd等晶格常数：底面边长a和高c，c/a=1.633密排六方晶格⑷closed-packedplanesandorientationsofthethreeordinarycrystallatticesAtomicityonunitareaofthecrystalplaneiscalledcrystalplaneatomicdensity.Atomicityonunitlengthofthecrystalorientationiscalledcrystalorientationatomicdensity.Thecrystalplane
7、orcrystalorientationwiththelargestatomicdensityiscalledclosedpackedplaneorclosedpackedorientation.Closed-packedplanesamountClosed-packedorientationsamountBodycenteredcubiccrystallattice{110}6<111>4Facecenteredcub
