材料科学与工程基础13317.pptx

Fundamentals of materials science and engineeringChapter 1 Introduction to Materials Science and EngineeringHave You Ever Wondered?What do materials scientists and engineers study?What do materials scientists and engineers study?How sheet steel can be processed to produce a high-strengthHow sheet steel can be processed to produce a high-strength，lightweightlightweight，energy absorbingenergy absorbing，malleablemalleable（可塑的，可锻的）（可塑的，可锻的）material used in the manufacture of car chassismaterial used in the manufacture of car chassis（底盘）（底盘）?Can we make flexible and lightweight electronic circuitsCan we make flexible and lightweight electronic circuits using plastics?using plastics?What is a“smart material”?What is a“smart material”?outlinen nWhat is Materials Science and Engineering?n nClassification of Materialsn nEnvironmental and Other Effectsn nMaterials Design and Selection1-1 What is Materials Science and Engineering?n n1.Definition Materials Science and Engineering(MSE)is an interdisciplinary field concerned with inventing new materials and improving previously known materials by developing a deeper understanding of the microstructure-composition-synthesis-processing relationship.The term Composition Means the chemical make-up of a materialStructureA description of the arrangement of atoms,as seen at different levels of detail.SynthesisRefers to how materials are made from naturally occuring or man-made chemicals.ProcessingMeans how materials are shaped into useful components to cause changes in the properties of different materials.Figure Application of the tetrahedron of materials science and engineering to sheet steels for automotive chassis.Note that the microstructure-synthesis and processing-composition are all interconnected and affect the performance-to-cost ratioComposition;Strength;Weight;Energy absorption properties;Malleability(formability)Strength-to-weight ratio is the strength of a material divided by its density;materials with a high strength-to-weight ratio are strong but lightweight.Figure Application of the tetrahedron of materials science and engineering to semiconducting polymers for microelectronics.rubst 结实的；耐用的；坚固的 Synthesis and processing How can pure,homogeneous,and fine powders of well-defined stoichiometry be made?How do we make long lengths of wires?Figure Application of the tetrahedron of materials science and engineering to ceramic superconductorsceramic superconductors.Note that the microstructure-synthesis and processing-composition are all interconnected and affect the performance-to-cost ratio What is the current carrying capacity?What is the cast of cooling and fabrication?Microstructure What features of the structure limit the current carrying capacity?What is the texture of the material?Composition YBa2Cu3O7-x YBa2Ca3Cu4O11 YSr2Ca2Cu3O10Performance Cast Tetrahedron of MSE2.Materials Sciencen nThe emphasis is on the underlying relationships between the synthesis and processing,structure,and properties of materials.3.Materials Engineeringn n The focus is on how to translate or transform materials into a useful device or structure.Application OF Tetrahedron:a sample product ceramic superconductors invented in 1986(1)DISCOVERY(2)LIMITATION(3)IMPROVEMENT(4)SOLUTION(5)BRITTLE(6)SOLUTION 1-2 Classification Of Materialsn nAccording to different propertiesn nFunctional Classification of Materialsn nClassification of Materials Based on Structure(microstructure)Classification Classification Properties Properties ApplicationApplication Metals Metals good electrical and thermal conductivity automobile engine good electrical and thermal conductivity automobile engine(steels,aluminum,relatively high strength,stiffness,aircraft,electrical(steels,aluminum,relatively high strength,stiffness,aircraft,electrical magnesium)ductivity,formability conductor wiremagnesium)ductivity,formability conductor wireCeramics Ceramics high melting point,strength,hardness house computer chip high melting point,strength,hardness house computer chip (Si,SiO(Si,SiO2 2,Al,Al2 2O O3 3,capacitors,electrical insulation ,capacitors,electrical insulation ,MgO,SiC,Si,MgO,SiC,Si3 3N N4 4)sanitaryware,abrasive )sanitaryware,abrasive Polymers Polymers electrical resistivity,thermal insulation,food packaging electrical resistivity,thermal insulation,food packaging low strength liquid crystal displays low strength liquid crystal displays (LCD)(LCD)SemiconductorSemiconductor (Silicon,GaAs)convert electrical signals to light transistors,diodes(Silicon,GaAs)convert electrical signals to light transistors,diodes lasers,etc integrated circuits lasers,etc integrated circuitsCompositesComposites high hardness,good shock resistance,sports equipment,fiberglass high hardness,good shock resistance,sports equipment,fiberglass high strength-to-weight ratio aircraft,matrix high strength-to-weight ratio aircraft,matrix1.According to different properties1.According to different propertiesBiomaterials 生物功能性生物功能性(biofunctionability)和生物相容性(biocompatibility)metallic,ceramic,polymer materials finger joint teeth 手指关节Figure Representative strengths of various categories of materials聚醚酮树脂聚乙烯环氧树脂芳纶纤维聚酰亚胺 聚酯纤维，涤纶2.Functional Classification of Materialsn nAerospaceAerospace（航空航天）（航空航天）light materials light materialsn nBiomedical MaterialsBiomedical Materialsn nElectronic MaterialsElectronic Materialsn nEnergy Technology and Environmental TechnologyEnergy Technology and Environmental Technologyn nMagnetic MaterialsMagnetic Materialsn nPhotonic or Optical Materials(Photonic or Optical Materials(光学材料）光学材料）n nSmart MaterialsSmart Materialsn nStructural MaterialsStructural MaterialsStructuralSteel Aluminum alloysConcrete FiberglassPlastic,WoodSmart materialsPZTShape-memory alloysMR fluidPolymer gelsOpticalMaterialsSiO2,GaAsGlasses,Al2O3YAG,ITO Fe,Fe-Si,NiZn And MnZn ferrites;Co-Pt-Ta-Crg-Fe2O3UO2,Ni-Cd,ZrO2,LiCoC2,Amorphous Si:HSi,GaAs,Ge,BaTiO3,PZT,YBa2Cu3O7,Al,Cu,W,ConductingpolymerBiomedical Hydroxyapatite羟磷灰石 Titanium alloys,Stainless steelsShape-memory alloysPlastics,PZTAerospace C-C composites,SiO2,Amorphoussilicon,Ai-alloysSuperalloysMagneticMaterialsEnergy Technology&EnvironmentalElectronic Materials Figure Functional classification of materials.Notice that metals,plastics,and ceramics occur in different categories.A limited number of examples in each category is providedClassification ofFunctionalMaterialsITO:In2O3-SnO2MR:magnetorheologyPZT:lead zicornium titanateYAG:yttrium aluminum garnet(Y3Al5O12)磁流体铟-锡压电陶瓷(锆钛酸铅)(Y3Al5O12)(Y3Al5O12)3.Classification of Materials Based on Structure(microstructure)n nCrystal Crystal（晶体）（晶体）-the materials atoms are -the materials atoms are arranged in a periodic fashion.arranged in a periodic fashion.n nAmorphousAmorphous（非晶体）（非晶体）-the materials atoms do-the materials atoms do not have a long-range order.not have a long-range order.n nSingle crystalsSingle crystals（单晶）（单晶）-some crystalline-some crystalline materials may be in the form of one crystal.materials may be in the form of one crystal.n nPolycrystalsPolycrystals（多晶）（多晶）-some crystalline materials-some crystalline materials consist of many crystals or grains.consist of many crystals or grains.SEM5 nmMSEXRD,TEM Optical 19 transparencytransparency 透明度:-氧化铝因其结构不同而透明、半透明、不透明Adapted from Fig.1.2,Callister 7e.(Specimen preparation,P.A.Lessing;photo by S.Tanner.)单晶(transparent)多晶：低孔隙度（translucent;semitransparent）多晶：高孔隙度 （opaque）1-3 Environmental and Other Effectsn nTemperaturen nCorrosionn nFatigue n nStrain Rate 1.TemperatureHigh temperature-change the structure ofchange the structure of ceramics and cause polymers to melt or char ceramics and cause polymers to melt or charLow temperature-cause a metal or polymers to fail in Low temperature-cause a metal or polymers to fail in a brittle manner,even though the applied loads are a brittle manner,even though the applied loads are low.low.Figure Increasing temperature normally reduces the strength of a material.Polymers are suitable only at low temperatures.Some composites,special alloys,and ceramics,have excellent properties at high temperaturesTEMPERATUREEMPERATUREFigure A section through a jet engine.The forward compression section operates at low to medium temperatures,and titanium parts are often used.The rear combustion（尾部燃烧）（尾部燃烧）section operates at high temperatures and nickel-based superalloys are required.The outside shell experiences low temperatures,and aluminum and composites are satisfactory.(Courtesy of GE Aircraft Engines.)Figure A variety of complex ceramic components,including impellers（叶轮）（叶轮）and blades,which allow turbine engines to operate more efficiently at higher temperatures.(Courtesy of Certech,Inc.)Figure Polymers are used in a variety of electronic devices,including these computer dipswitches,where moisture resistance and low conductivity are required.(Courtesy of CTS Corporation.)Figure Integrated circuits for computers and other electronic devices rely on the unique electrical behavior of semiconducting materials.(Courtesy of Rogers Corporation.)Figure The X-wing for advanced helicopters relies on a material composed of a carbon-fiber-reinforced polymer.(Courtesy of Sikorsky Aircraft DivisionUnited Technologies Corporation.)2.Corrosionn noxygen or other gasesn nLiquidn nRadiation（辐射）,atomic oxygen,debris（碎石，废石）2.Corrosionn n oxygen or other gases(1)Most metals and polymers react with oxygen or other gases,particularly at elevated temperatures.(2)Metals and ceramics may disintegrate.(3)Nonoxide ceramics and polymers may oxidize.liquidn nacid（酸）alkali（碱）salt（盐）-leading to premature failureRadiationRadiation（辐射）（辐射）（辐射）（辐射）,atomic oxygen,debris,atomic oxygen,debris（碎石，废（碎石，废（碎石，废（碎石，废石）石）石）石）n n In space applications,we may have to consider the effects In space applications,we may have to consider the effects of the presence of radiation,the presence of atomic oxygen,of the presence of radiation,the presence of atomic oxygen,and the impact from debris.and the impact from debris.3.Fatigue load and unload the material thousands of times small cracks cracks grow materials fail4.Strain Rate n nIf we pull it slowly,the material can be stretched significantly.n n If we pull it fast,the material snaps.1-4 Materials Design and Selection Physical and mechanical propertiesPhysical and mechanical properties Design for a given applicationDesign for a given application a number of factorsa number of factors economical solution economical solution Protect environmentProtect environment Recycling of the materials Recycling of the materials compositioncomposition synthesis and processing synthesis and processing internal structure internal structureA good engineer will consider:n nthe effect of how the material is made;the effect of how the material is made;n nwhat exactly is the composition of the candidate what exactly is the composition of the candidate material for the application being considered;material for the application being considered;n nprocessing have to be done for shaping the material processing have to be done for shaping the material or fabricating a component;or fabricating a component;n nthe structure of the material after processing into a the structure of the material after processing into a component or device;component or device;n nthe environment in which the material will be used;the environment in which the material will be used;n ncost-to-performance ratio.cost-to-performance ratio.n nThe knowledge of principles of materials science and engineering will empower you with the fundamental concepts.n nThese will allow you to make technically sound decisions in designing with engineered materials.演讲完毕，谢谢观看！