Chapter 1 Introduction to Materials Definition材料的定义材料的定义Types材料的类型材料的类型Structure材料的结构材料的结构 Structure properties processing 结构性能工艺之间的关系结构性能工艺之间的关系1Classification of Materialsl Basis of classification: atomic structures nature of chemical bonds:金属键金属键 Metallic bond离子键离子键 Ionic bond共价键共价键 Covalent bond范德华健范德华健 Van der Waals bond氢键氢键 Hydrogen bond2 Classification（按按物理化学属性物理化学属性） Metallic materials 金属材料金属材料 Inorganic-nonmetallic materials 无机非金属材料无机非金属材料 Polymeric materials 有机高分子材料有机高分子材料 Composite materials 复合材料复合材料3Propertiesl Mechanical properties: the behavior of materials deformed by a set of forces. Physical properties: the behavior of materials subjected to the action of temperature, electric or magnetic fields, or light. Chemical properties: the behavior of material in a reactive environment.4The four basic aspects of materials science and technology 51.Types of Materials MetallCharacteristics / propertiesis strong;can be readily formed into practical Its ductility is an important asset in permitting small amounts of yielding to sudden and severe loads. 6l Types Ferrous metals: pig iron, carbon steel, pure iron Non-ferrous metals: heavy, light, valued and rare metals Special metals: non-crystalline, shape memory alloy7CeramicslCharacteristics / properties: brittlelRecent development in technologylStructural feature: crystalline: the constituent atoms are stacked together in a regular, repeating pattern. noncrystalline: the atoms are stacked in irregular, random patterns. glass: noncrystalline solids8PolymerslComposition: hydrogen and carbon, oxygen lPropertiesLightweightlow-cost low strength low melting point, andhigher chemical reactivity 93. Structural Characteristic of Materials4. 5.Forms of solids: crystalline & amorphous Crystalline: an ordered arrangement of the elementary particles (ions, atoms or molecules). 晶体结构晶体结构: 晶体中原子（或离子）在空晶体中原子（或离子）在空 间规则排列的方式。间规则排列的方式。103.1 Properties of crystalsDepend on:the electronic structure of atoms the nature of the interactions in the crystalthe spatial arrangement of elementary particles, and the composition, size and shape of crystals. 11Anisotropy 各向异性各向异性: The properties of crystals are different in various crystallographic directions, which are associated with an ordered arrangement of atoms (ions, molecules) in space. This phenomenon is called anisotropy. 123.2 Crystal Lattice 晶格晶格 Arrangement of elementary particles in a crystal (a): three-dimensional view (b): scheme13 Types of elementary cell: simple three-dimensional lattice 简单立方格子简单立方格子 body-centred cell 体心立方格子体心立方格子 face centred cell 面心立方格子面心立方格子14Types of elementary cell in crystal lattices (a): simple (b): body-centred cell (c): face centred cell 154. Structure-Property-Processing 5. Relationship 4.1 Properties 力学性能力学性能 Mechanical property 强度强度 Strength在外力作用下材料抵抗塑性变形或在外力作用下材料抵抗塑性变形或断裂的能力称为强度。单位断裂的能力称为强度。单位MPa。16抗压强度抗压强度 Compressive strength- 材料破坏之前所能够承受的最大压应力材料破坏之前所能够承受的最大压应力PP17抗拉强度抗拉强度 Tensile strength- 材料破坏之前所能够承受的最大拉应力材料破坏之前所能够承受的最大拉应力PP18 弹性模量弹性模量 Modulus of elasticity 硬度硬度 Hardness材料抵抗硬物压入其表面的能力，材料抵抗硬物压入其表面的能力，即抵抗局部塑性变形的能力即抵抗局部塑性变形的能力。 韧性韧性 Toughness材料抵抗裂纹萌生与扩展的能力材料抵抗裂纹萌生与扩展的能力。 疲劳特性疲劳特性 Fatigue behaviour19 物理和化学性能物理和化学性能 Physicochemical property 电性能电性能 Electric properties- 导电性导电性 Electric conductivity以材料的电阻率或电导率评价以材料的电阻率或电导率评价。- 介电介电 性性 Dielectric properties 能把带电体分开并能长期经受强电能把带电体分开并能长期经受强电 场作用的绝缘材料叫介电材料或电场作用的绝缘材料叫介电材料或电 介质介质。20压电性压电性 Piezoelectricity介电材料在应力作用下发生尺寸变介电材料在应力作用下发生尺寸变化时因极化而产生电场或电压，这化时因极化而产生电场或电压，这种现象称为压电性种现象称为压电性。铁电性铁电性 Ferroelectricity 有些离子晶体没有外电场作用也能有些离子晶体没有外电场作用也能表现出很强的电偶极矩，这种能自表现出很强的电偶极矩，这种能自发极化的现象叫铁电效应发极化的现象叫铁电效应。21 磁性能磁性能 Magnetic properties抗磁性物质抗磁性物质 Antimagnetic 减弱磁场减弱磁场顺磁性物质顺磁性物质 Paramagnetic 使磁场略有增加使磁场略有增加铁磁性物质铁磁性物质 Ferromagnetic 使磁场强裂增加使磁场强裂增加22 热性能热性能 Thermal properties 吸热吸热：热容；热容；传热传热：热导率；：热导率； 膨胀膨胀：热膨胀系数：热膨胀系数 光学性能光学性能 Optical properties吸收、透射、反射吸收、透射、反射234.2 Structurel Structural levels:Macrostructure: visible with eyes or optical microscope;Meso-structure: Optical or SEM, ranging 10-710-4m;Microstructure: Arrangements of atoms and molecules.244.3 Processing lFor metalsCasting 铸造: by pouring liquid metal into a mold Welding 焊接/ brazing铜焊 / soldering锡焊 / adhesive bonding: joining individual pieces of metal 25Forging 锻造/ drawing拉拔 / extrusion 挤压/ rolling碾压 / bending弯曲: forming the solid metal into useful shapes using high pressuresPowder metallurgy: compacting tiny metal powder particles into a solid massMachining: removing excess materials26lFor ceramicscasting, forming, extrusion, compactionheat treatment at high temperatures to drive off the fluids and to bond the individual constituents together. For polymers by injection of softened plastic into molds, drawing and forming. 274.4 Structure-property-processing interaction lProcessing: affecting structure & properties lProcessing: determined by structure & properties 28Summary: lDefinition of materialslClassification of materialslChacteristics of each type of materialslChemical bondslStructure feature of crystallPrpert