材料学导论复习及翻译.docx

Atomic Structure and Interatomic Bonding：（原子结构和原子间键合）n Chapter Outline -Review of Atomic Structure Electrons, Protons, Neutrons, Quantum mechanics of atoms, Electron states, The Periodic Table（电子质子中子量子原子电子态，在周期表中的力学）n Atomic Bonding in Solids Bonding Energies and Forcesn Periodic Table n Primary Interatomic Bonds Ionic, Covalent, Metallic（离子型，共价键，金属）n Secondary Bonding (Van der Waals) 次级键 Three types of Dipole Bondsn Molecules and Molecular Solids n Chapter Outline Understanding of interatomic bonding is the first step towards understanding/explaining materials properties了解原子间键合是迈向理解/解释材料性能的第一步n Electronegativity - a measure of how willing atoms are to accept electronsBonding force and energies：n This is typical potential well for two interacting atoms The repulsion between atoms, when they are brought close to each other, is related to the Pauli principle:when the electronic clouds surrounding the atoms starts to overlap, the energy of the system increases abruptly. The origin of the attractive part, dominating at large distances, depends on the particular type of bonding这是典型的势阱，用于两个相互作用的原子的原子之间的斥力，当它们被带到彼此靠近，是关系到泡利原理：当周围的原子的电子云开始重叠，该系统增大了能量突然。迷人的部分的起源，雄踞在大的距离，取决于特定类型的粘接上 Primary interatomic bonds：n Primary bonding: e- are transferred or shared n Strong (100-1000 KJ/mol or 1-10 eV/atom) n Ionic bonding: 负离子结合力n Strong Coulomb interaction among negative atoms (have an extra electron each) and positive atoms (lost an electron). Example - Na+Cl- 负原子之间强大的库仑相互作用（有一个额外的电子每个）n Covalent: electrons are shared between the molecules, to saturate the valency. Example - H2 共价：电子在分子之间共享，以饱和的化合价。n Metallic: the atoms are ionized, loosing some electrons from the valence band. Those electrons form a electron sea, which binds the charged nuclei in place 金属：原子被电离，失去了从价带的一些电子。这些电子形成的电子云，其中结合带电原子核到位n Formation of ionic bond: 离子键n 1. Mutual ionization occurs by electron transfer (remember electronegativity table) 双方发生电离通过电子转移n Ion = charged atom 离子=电荷的原子n Anion = negatively charged atom 负离子=负电荷的原子n Cation = positively charged atom 阳离子=带正电的原子n 2. Ions are attracted by strong coulombic interaction Oppositely charged atoms attractAn ionic bond is non-directional (ions may be attracted to one another in any direction 离子以强大的库仑相互作用带相反电荷的原子吸引一个离子键是无方向性（离子可在任何方向上被吸引到彼此吸引Formation of covalent bonds: Cooperative sharing of valence electrons Can be described by orbital overlap Covalent bonds are HIGHLY directional 共价键的形成：协同共享价电子可以通过轨道重叠描述共价键是高度定向n Bonds - in the direction of the greatest orbital overlap Covalent bond model: an atom can covalently bond with at most 8-N, N = number of valence electrons -最大的轨道重叠共价键模型的方向：一个原子可以共价键与价电子至多8-N，N=号n Metallic Bondingn Valence electrons are detached from atoms, and spread in an electron sea that glues the ions together.价电子从原子中分离，并在流传一个“电子云”的“胶水”离子在一起。n A metallic bond is non-directional (bonds form in any direction)金属键是无方向的n atoms pack closely Fundamental concepts：n Crystalline material: atoms self-organize in a periodic array结晶物质：原子自发组织的一个周期阵列n Single crystal: atoms are in a repeating or periodic array over the entire extent of the material单晶：原子是在重复或周期性阵列在材料的整个范围n Polycrystalline material: comprised of many small crystals or grains 多晶材料：许多小晶体或颗粒组成n Amorphous: lacks a systematic atomic arrangement 无定形的：缺乏一个系统的原子排列3.3 Unit cells：n The unit cell is the smallest structural unit or building block that can describe the the crystal structure. Repetition of the unit cell generates the entire crystal. 晶胞是最小的结构单元，或构建块，可以描述晶体结构。晶胞的重复生成整个晶体。3.4 Metallic crystal structure：The coordination number, CN = the number of closest neighbors to which an atom is bonded = number of touching atoms, CN = 12 配位数，IN =到一个原子结合最近的邻居的数量=接触的原子数，CN=12Number of atoms per unit cell, n = 4. (For an atom that is shared with m adjacent unit cells, we only count a fraction of the atom, 1/m). In FCC unit cell we have: 6 face atoms shared by two cells: 6 x 1/2 = 3, 8 corner atoms shared by eight cells: 8 x 1/8 = 1Atomic packing factor, APF = fraction of volume occupied by hard spheres = (Sum of atomic volumes)/(Volume of cell) = 0.74 (maximum possible) 堆积因子，APF=（原子体积之和）占用的体积分数/（细胞体积）=0.74（最大可能）3.5 Density computation：n , the density of a crystalline material, the density of the unit cell r= (atoms in the unit cell, n ) (mass of an atom, M) / (the volume of the cell, Vc) 结晶材料，晶胞=（在该单元中，n个原子）的密度的密度（质量的原子的，M）/（细胞的体积，Vc）的n Atoms in the unit cell, n = 2 (BCC); 4 (FCC); 6 (HCP)n Mass of an atom, M = Atomic weight, A, in amu (or g/mol) is given in the periodic table. 原子的质量M=原子量，A，在原子量（或克/摩尔）是由于在周期表。 n To translate mass from amu to grams we have to divide the atomic weight in amu by the Avogadro number NA = 6.023 1023 atoms/mol细胞的体积，VC= A3（FCC和BCC）为a =2R2（FCC）;一个=4R3（BCC），其中R是原子半径Chapter 4. Polymer Structuren Isomers are molecules that contain the same atoms but in a different arrangement. An example is butane and isobutane: 异构体是指含有相同的原子，但在不同的排列的分子。一个例子是丁烷和异丁烷n Repeat unit in a polymer chain (“unit cell”) is a mer unit 在聚合物链（“单元电池”）的重复单元是一个链节单元n A single mer is called a monomer单聚体被称为单体n When all the mers are the same, the molecule is called a homopolymer 当所有的链节是相同的，该分子被称为均聚物n When there is more than one type of mer present, the molecule is a copolymer 当存在多于一种类型的链节目前，该分子是一种共聚物n Mer units that have 2 active bonds to connect with other mers are called bifunctional Mer units that have 3 active bonds to connect with other mersure called trifunctional.They form three- dimensional molecular network structures4.5 Molecular weight (I)n Final molecular weight (chain length) is controlled by relative rates of initiation, propagation, termination steps of polymerization 最终分子量（链长）由引发，增长终止步聚合的相对速率控制n Formation of macromolecules during polymerization results in distribution of chain lengths and molecular weights 大分子的过程中聚合结果形成的链长和分子量分布n The average molecular weight can be obtained by averaging the masses with the fraction of times they appear (number-average molecular weight) or with the mass fraction of the molecules (weight-average molecular weight).Molecular weight (II)平均分子量可以通过用次出现（数均分子量）的馏分或与分子（重均分子量）的质量分数平均群众得到。分子量（II）的n Alternative way to express average polymer chain size is degree of polymerization - the average number of mer units in a chain:表达均聚合物链大小的替代方法是聚合度- 中体单元链中的平均数：. Linear polymers:Van der Waalsbonding between chains. Examples: polyethylene, nylon。线性聚合物：链之间的范德华力。例如：聚乙烯，尼龙. Branched polymers:Chain packing efficiency is reduced compared to linear polymers - lower density支化聚合物：链包装效率相比，线性聚合物减少- 密度较低. Cross-linked polymers:Chains are connected bycovalent bonds.Often achieved by adding atoms or molecules that form covalent links between chains. Many rubbers have this structure.交联的聚合物：链条连接bycovalent通过添加形成链间的共价连结的原子或分子来实现bonds.Often。许多橡胶有这样的结构。Isomerism: Hydrocarbon compounds with same composition may have different atomic arrangements. Physical properties may depend on isomeric state (e.g. boiling temperature of normal butane is-0.5 oC, of isobutane-12.3 oC)异构：烃类化合物具有相同的成分可能有不同的原子排列。物理性质可能取决于异构态（正常丁烷 - 0.5摄氏度，例如沸点温度的异丁烷- 12.3摄氏度，）4.8 Thermoplastic and Thermosetting Polymersn Thermoplasts soften when heated (and eventually polymers) and hardened when cooled-process that are totally reversible and may be repeated. secondary bonding forces are diminished so that relative movement of adjacent chains is facilitated when a stress is applied. Thermosetting polymers become permanently hard when heat is applied and do not soften upon subsequent heating当加热热塑性塑料软化（最终聚合物），当冷却过程是完全可逆的，并且可以重复硬化。 - 次级粘接力减弱，使得相邻的链的相对移动，当一个应力施加变得容易。热固性聚合物成为永久很难当加热时，并在随后的加热不软化n Degree of crystallinity is determined by: Rate of cooling during solidification: time is necessary for chains to move and align into a crystal structure 速率冷却凝固过程中：结晶度由下式确定时间是必要的链来移动和对准成晶体结构n Mer complexity: crystallization less likely in complex structures, simple polymers, such as polyethylene, crystallize relatively easily 聚体的复杂性：结晶不太可能在复杂的结构，简单的聚合物，如聚乙烯，结晶比较容易地n Chain configuration: linear polymers crystallize relatively easily, branches inhibit crystallization, network polymers almost completely amorphous, cross- linked polymers can be both crystalline and amorphous链构型：直链聚合物结晶比较容易，抑制枝晶，网状聚合物几乎完全无定形的，交联的聚合物既可以是结晶和无定形n Isomerism: isotactic, syndiotactic polymers crystallize relatively easily -geometrical regularity allows chains to fit together, atactic difficult to crystallize异构：等规，间规聚合物结晶相对容易，几何规则允许链结合在一起，无规难以结晶Copolymers easier to crystallize if mer arrangements are more regular - alternating, block can crystallize more easily as compared to random共聚物：容易结晶，如果MER安排都比较正规 - 交替，嵌段可以比随机结晶更容易Chapter 5 Imperfections in SolidsVacancy - a lattice position that is vacant because the atom 空缺- 晶格位置是空的，因为原子Interstitial -an atom that occupies a place outside the normal lattice position. It may be the same type of atom as the others (self interstitial) or an impurity interstitial atom.间杂质占据了正常晶格位置以外的地方原子。它可以是相同类型的原子为他人（个体间质）或杂质的填隙原子。n One type of defect involves a cation-vacancy and a cation interstitial pair. This is called Frenkel defect.一种类型的缺陷包括阳离子空位和填隙阳离子对。这就是所谓的Frenkel缺陷。n Another type of defect found in AX materials is a cation-anion vacancy pair called Schottky defect. created by removing one cation and one anion from the interior of the crystal. 另一种类型的缺陷在AX材料发现是阳离子，阴离子空位对称为肖特基缺陷。通过从晶体的内部除去一个阳离子和一个阴离子的产生。n Stoichiometry may be defined as a state for ionic compounds where there is exact ratio of cations to anions as predicted by the chemical formula.化学计量可以被定义为离子化合物在有阳离子对阴离子的确切比率作为预测用化学式的状态。n Nonstoichiometry may occur for some ceramic materials in which two valence states exist for one of the ion types.非化学计量可能会出现在其中两种价态的离子类型中的一种存在一些陶瓷材料。n Solid SolutionsSolid solutions are made of a host (the solvent or matrix) which dissolves the minor component (solute). The ability to dissolve is called solubility. 固溶体是由一个主机（溶剂或基质），其溶解的次要成分（溶质）的。以溶解能力称为溶解性。n homogeneous 同质 n maintain crystal structure 保持晶体结构n contain randomly dispersed impurities 包含随机分散的杂质n There are two types of impurity point defects in solid solution - substitutional or interstitial.有两种类型的杂质点缺陷在固溶体- 取代或填隙。n A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned.位错是一种直链的或一维的缺陷在其周围的一些原子的未对齐。n The interatomic bonds are significantly distorted only in the immediate vicinity of the dislocation line. This area is called the dislocation core. Dislocations also create small elastic deformations of the lattice at large distances. 原子间键仅在错线的附近显著扭曲。这个区域被称为位错核心。位错也是在大的距离创建格子小弹性变形。n Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures and/or crystallographic orientations. These imperfections include external surfaces, grain boundaries, twin boundaries, stacking faults, and phase boundaries.界面缺陷是具有两个维度，通常分离的区域具有不同的晶体结构和/或结晶取向的材料的边界。这些缺陷包括外表面，晶界，孪晶界，堆垛层错，和相界。n Polycrystalline material comprised of many small crystals or grains.The grains have different crystallographic orientation. There exist atomic mismatch within the regions where grains meet. These regions are called grain boundaries.由许多小晶体或grains.The颗粒多晶材料具有不同的晶体取向。那里有谷物满足区域内的原子存在不匹配。这些区域被称为晶界。 Chapter 6 Diffusionn Diffusion is material transport by atomic motion. 扩散是原子运动n Self-diffusion is diffusion in one-component material, when all atoms that exchange positions are of the same type. 自扩散是扩散的单组分材料，当该交换位置的所有原子都是相同类型的。n Interstitial diffusion is generally faster than vacancy diffusion because bonding of interstitials to the surrounding atoms is normally weaker and there are many more interstitial sites than vacancy sites to jump to. 质子扩散通常比空位扩散得更快，因为间隙的周围的原子的键合，通常较弱，有更多的间隙位置比空位站点跳转到。n Steady-State Diffusion the diffusion flux does not change with time稳态扩散扩散通量不随时间而变化n Diffusion Flux.扩散通量。n The flux of diffusing atoms, J, is used to quantify how fast diffusion occurs. The flux is defined as either in number of atoms diffusing through unit area and per unit time (e.g., atoms/m2-second) or in terms of the mass flux - mass of atoms diffusing through unit area per unit time, (e.g., kg/m2-second). 扩散原子的通量，J，用于量化如何快速发生扩散。通量被定义为以原子单位面积的扩散通过的数目和每单位时间（例如，atoms/m2-second），或在质量通量方面 - 的原子单位面积的扩散通过每单位时间的质量（例如，千克/平方米秒）。n Steady state diffusion: the diffusion flux does not change with time. 稳态扩散：扩散通量不随时间而改变。 6.5 Factors that influence diffusion（论述题）n 1. Diffusion species (vacancy and interstitial species)1。扩散的物种（空位和填隙） Self- and interdiffusion 自扩散和相互扩散 Self-diffusion occurs by a vacancy mechanism, whereas carbon diffusion in iron is interstitial.自扩散所产生的空缺的机制，而在铁碳扩散是间隙。n 2. Temperature - diffusion rate increases very rapidly with increasing temperature 温度 - 扩散率增加非常迅速，随着温度的升高n 3. Diffusion mechanism - interstitial is usually faster than vacancy扩散机制 - 间隙通常比空位快 n 4. Microstructure - diffusion faster in polycrystalline vs. single crystal materials because of the accelerated diffusion along grain boundaries and dislocation cores.微观 - 因为沿晶界和位错核心加速扩散的扩散在多晶与单晶材料更快。When an external electric field is applied across an ionic solid, the electrically charged ions migrate (i.e, diffuse) in response to forces ( caused by electric filed). This ionic motion gives rise to an electric current. The electrical conductivity is a function of the diffusion coefficient. Therefore, much of the diffusion data for ionic solids comes from electrical conductivity measurement当外部电场穿过的离子型固体应用，该带电离子响应于力（所造成的电场）迁移（即，漫射）。这种离子的运动产生了电流。电导率是扩散系数的函数。因此，大部分的扩散数据为离子型固体的来自电导率测定Chapter 7. Mechanical Properties7.3 Stress- strain behavior（论述题）n Elastic deformation Reversible: when the stress is removed, the material returns to the dimension it had before the loading. Usually strains are small (except for the case of plastics). 弹性变形可逆的Plastic deformation Irreversible: when the stress is removed, the material does not return to its previous dimension塑性变形的不可逆的：当应力被除去，该材料不会返回到其先前的尺寸However, (many engineering materials) in reality elastic deformation takes time (finite rate of atomic/molecular deformation processes) - continues after initial loading, and after load release. This time dependent elastic behavior is known as anelasticity.然而，（许多工程材料）在现实中弹性变形需要时间（原子/分子变形过程的有限速率） - 继续在初始装载后，经过负载释放。这种随时间变化的弹性行为被称为滞弹性。Plastic deformation: stress and strain are not proportional 应力和应变不成正比the deformation is not reversible 变形是不可逆的deformation occurs by breaking and re-arrangement of atomic bonds (in crystalline materials primarily by motion of dislocations, 变形发生由主要由位错的运动和断裂的原子键重新排列Yield strength (yield stress) sy - is chosen as that causing a permanent strain of 0.002 屈服强度（屈服应力）Y - 被选择作为造成的0.002的永久应变Yield point P - the strain deviates from being proportional to the stress (the proportional limit) 屈服点P - 应变从正比于应力（比例极限）偏离。The yield stress is a measure of resistance to plastic deformation n Ductility is a measure of the degree of plastic deformation that has been sustained at fracture. A material that experiences very little or no plastic deformation up fracture is termed brittle. ( Materials have a fracture strain of less than 5% are considered to be brittle materials.)延展性是已经被维持在断裂塑性变形的程度的一种度量。这经验很少或没有塑性变形断裂了被称为脆性的材料。 （材料具有小于5断裂应变被认为是脆性材料。）n Toughness = the ability to absorb energy up to fracture = the total area under the strain-stress curve up to fracture Units: the energy per unit volume, e.g. J/m3 Can be measured by an impact test韧性=吸收能量高达断裂的能力=应力应变曲线向上下的总面积破裂单位：每单位体积的能量，例如J/m3可以通过冲击试验来测定 n True stress = load divided by actual area in the necked-down region, continues to rise to the point of fracture, in contrast to the engineering stress. 真应力=负载通过实际面积在颈缩区域划分，继续上升至断裂的点，与此相反的工程应力。n If a material is deformed plastically and the stress is then released, the material ends up with a permanent strain. If the stress is reapplied, the material again responds elastically at the beginning up to a new yield point that is higher than the original yield point. The amount of elastic strain that it will take before reaching the yield point is called elastic strain recovery. 如果材料发生塑性变形，应力被释放，该材料最终获得一个永久应变。如果该应力被重新应用，该材料再次响应弹性在开始了一个新的屈服点比原来的屈服点高。弹性应变，这将需要达到屈服点之前的量称为弹性应变恢复。n Hardness is a measure of the materials resistance to localized plastic deformation (e.g. dent or scratch).硬度是局部的塑性变形（例如，凹坑或划痕）的材料的抗性的测量。Chapter 8. Deformation and strengthening mechanismsPlastic deformation is due to the motion of a large number of dislocations.塑性变形是由于大量位错的运动。n The process by which plastic deformation is produced by dislocation motion is termed slip.通过该塑性变形是通过位错运动产生的过程称为滑动。n The crystallographic plane along which the dislocation line traverses is the slip plane晶面沿其位错线是穿过滑动面8.9 Strengthening by grain size reduction（简答。论述）n The ability of a metal to deform depends on the ability of dislocations to move Restricting dislocation motion makes the material stronger.一个金属的变形能力取决于位错的移动限制位错运动使材料更强的能力。n Mechanisms of strengthening in single-phase metals:n 1. grain-size reduction 晶粒尺寸减小 n 2. solid-solution alloying 固溶合金 n 3. strain hardening应变硬化n 1. Grain boundary barrier to dislocation motion: slip plane discontinues or change orientation.晶界阻碍位错运动：滑移面会终止或改变方向。n 2. Small angle grain boundaries are not very effective in blocking dislocations. 小角度晶界不能非常有效地阻止位错。n 3. High-angle grain boundaries block slip and increase strength of the material. A stress con