材料工程专业英语4晶格缺陷Imperfections-in-solids课件

,*,材料工程专业英语,材料工程专业英语,材料工程专业英语4晶格缺陷Imperfections-in-solids课件,Imperfections in solids,Imperfections in solids,You may have known that the,actual,strength of most materials is much less than the,theoretical,one,but do you know why?,You may also have known that steel is much stronger than the pure iron because of the addition of some alloying elements,but why?,Is there any conflict between the answers of the two questions?,If you can not answer right now,it does not mater,because after learning this chapter,you may find that answering such questions is just,a piece of cake,.,Why study imperfections in solids?,You may have known that the ac,Designate the main types of the,point defects,in metals.,Understand the basic concept of the,edge,screw and the mixed dislocations,.,Understand the basic concept of the,interfacial defects,and describe the atomic structure,within the vicinity of(,a)a grain boundary and(b)a twin boundary.,Name the most common methods for microstructure examination.,What should you be able to do after studying this chapter?,Designate the main types of th,Defect,n.,imperfection/fault,Point defect,点缺陷,vacancy,空位；,interstitial atoms;impurity;solute,linear defect,线缺陷,Grain boundary,晶界,interfacial defect,面缺陷,mixed dislocation,混合位错,dislocation line,位错线,Edge dislocation,刃位错,Screw dislocation,螺位错,Burgers vector,伯格斯矢量,Words and Phrases,Defect n.imperfection/fault,Perfection n.,完美,imperfection,缺陷,Impurity n.,杂质,purity:clearness,Irregularity n.,不规则,regularity,规则,Geometry,几何学,lattice distortion,晶格畸变,solute,溶质,solvent,溶剂,stacking faults,堆垛层错,substitutional,置换的,interstitial,间隙的,solid solution,固溶体,Misaligned:,错排的,mismatched,Perfection n.完美 imperfectio,magnification,放大倍数,Microscopy/microscope,显微镜,microstructure,微观结构,micro,macro,photomicrograph,显微照片,Optical microscope (OM),光学显微镜,Scanning electron microscope(SEM),扫描电子显微镜,Transmission electron microscope(TEM),透射电子显微镜,Scanning probe microscope(SPM),扫描探针显微镜,weight percent,重量百分数,Atom percent,原子百分数,magnification 放大倍数,Be subject(adj.)to:affected by,受,影响,deliberately:on purpose,intentionally,故意地,randomly,任意的,Result in:lead to/produce/make sth happen/cause,导致,Result from:cause by,起因,Alloying:,合金化,Solid solution:,固溶体,Retained:keep/preserve/save,保留,Be analogical to:analogous/similar,类似的,host atoms,：基体原子,.,Adjacent:surrounding,相邻的,increase,decrease,Be subject(adj.)to:affecte,4.1 introduction:,For a crystalline solid we have tacitly assumed that perfect order exists throughout the material on all atomic scale,However,，,such an idealized solid does not exist,；,all contain large numbers of various,defects,or,imperfections,.,As a matter of fact,many of the properties of materials,are profoundly sensitive to,deviations from,crystalline,perfections,;the influence is not always negative,and often specific characteristics are,deliberately,(on purpose,intentionally,故意地,),fashioned(v.influence,影响,),by,the introduction of controlled amounts or numbers of particular defect.,4.1 introduction:For a crystal,By“crystalline defect”is meant a,lattice irregularity,having one or more of its dimensions,on the order of an atomic diameter,.Classification of crystalline imperfections is frequently made according to geometry or dimensionality of the defect.Several different imperfections are discussed in this Chapter including,point detects,(those,associated with,one or two atomic positions),，,linear(or one-dimensional)defects,，,as well as interfacial defects,，,or boundaries,，,which are two dimensional,Impurities in solids are also discussed,，,since impurity atoms may exist as point defects.Finally,techniques for the microscopic examination of defects and the structure of materials are briefly described,By“crystalline defect”is mea,Crystalline defect,(,晶体缺陷,):a lattice irregularity having one or more of its,dimensions,(,维数,),on the order of an atomic diameter,.,Classification of crystalline defects according to geometry or dimensionality:,Point defects(,点缺陷,)zero dimension,Linear defects(,线缺陷,),one dimension,Interfacial defects(,面缺陷,),two dimensions,Crystalline defect(晶体缺陷):a la,4.2 Point defects in metals,Vacancy or vacant lattice site(,空位,):,the simplest of the point defects,one normally,occupied,from which an atom is missing.,vacancy,4.2 Point defects in metalsva,All crystalline solids contain vacancies and in fact,it is not possible to create such a material that,is free of,these defects.It is only possible to,increase,or,decrease,the number of vacancies somehow.,For a given quantity of material,the number of the vacancies increases with temperature according to,Nv=Nexp(-Qv/kT),All crystalline solids contain,Self-,interstitial,(,填隙子,)is another kind of point defects,it is such that an extra atom is,crowded into,an interstitial site,，,a small void space that under ordinary circumstances is not occupied.,Self-interstitial,Self-interstitial,introduce(,引起,),a relatively large,distortion,(,畸变,),and usually have less chance to exist than vacancies.,Self-interstitial(填隙子)is anot,4.4 Impurities in sol