第一章固体材料的结构

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1、《材料科学基础》FundamentalsofMaterialsScience第一章第一章固体材料的结构Chapter1.TheStructureofMaterials本章要讨论的主要问题是：(1)为什么原子能结合成固体？(2)材料中存在哪几种键合方式？(3)决定键合方式的主要因素有哪些？(4)材料的哪些性能和其键合方式有密切的关系？(5)如何描述晶体中原子的排列？(6)金属晶体有哪些常见的晶体结构？QuestionsforChapter11.Whatiscrystalstructure?2.Whatiscrystallattice?3.Howmanytypesofbonding

2、betweenatoms?Whatarethemostimportantfactorsindeterminingthetypesofbonds?4.Whatistherelationshipbetweenbondsandpropertiesofmaterials?5.Howtodescribetheatomarrangementincrystalline?6.Whatarethemostmetal’scrystalstructures?1-1几何晶体学的基本知识Sec.1.1TheFundamentalsofGeometricCrystallologyThemostimport

3、antaspectofanyengineeringmaterialisitsstructure,becauseitspropertiesarecloselyrelatedtothisfeature.Tobesuccessful,amaterialsengineermusthaveagoodunderstandingofthisrelationshipbetweenstructureandproperties.1、原子之间的键合ThetypesofbondsAtomicscalestructure:Byatomicstructurewemean(1)Thetypesofatoms

4、present;(2)Thetypesofbondingbetweentheatoms;(3)Thewaytheatomsarepackedtogether.Thetwomajorclassesofatomicbondsareprimaryandsecondarybonds.Primarybondsaregenerallyoneormoreordersofmagnitudestrongerthansecondarybonds.Thethreemajortypesofprimarybondsareionic,covalentandmetallicbonds.Allprimaryb

5、ondsinvolveeitherthetransferofelectronsfromoneatomtoanotherorthesharingofelectronsbetweenatoms.Oneoftheimportantfactorsindeterminingthetypeofbandthatanatomwillformisitselectronegativity.（1）离子键与离子晶体IonicbondingThemostcommontypeofbondinacompoundcontainingbothelectropositiveandelectronegativeel

6、ementsistheIonicbonds.Thisbondinvolveselectrontransferfromtheelectropositiveatomtotheelectronegativeatom.12--------------------------------------------------------------------------------------西安工业大学材料与化工学院王正品《材料科学基础》FundamentalsofMaterialsScience第一章原子结合：电子转移，结合力大，无方向性和饱和性；离子晶体：硬度高，脆性大，熔点高、导

7、电性差。如氧化物陶瓷。（1）共价键与原子晶体covalentbondingCovalentbondsformincompoundscomposedofelectronegativeelements,especiallythosewithfourormorevalenceelectrons.Sincetherearenoelectropositiveatomspresent,the“extra”electronsrequiredtofillthevalenceshelloftheelectro