材料概论英文版武汉理工大学

Material:Solids used by man kind to produce items which constitute the support for hisliving environmentCharacteristics of materials◆Have certain compositions;◆Can be processed;◆With certain shape and color;◆Can be used and reused or recycled.◆特点:☐具有一定的成分和配比；☐可成型加工；☐保持一定形状和外观；☐具有使用价值并可回收再利用。

材料性能的决定因素◆组成材料的各元素的原子结构，◆原子间的相互作用、相互结合，◆原子或分子在空间的排列分布和运动规律,◆原子集合体的形貌特征。

Classification of materials◆Atomic structures◆Nature of chemical bonds:☐Metallic bond 金属键☐Ionic bond 离子键☐Covalent bond 共价键☐Secondary bond 次价键☐Van der Waals bond 范德华力☐Hydrogen bond 氢键Classification:◆metals and their alloys:- metallic bonding◆Organic polymers: Covalent bonding & secondary bonding◆Ceramics:Ionic bonding & covalent bondingMetals and their alloys:◆are good conductors of heat and electricity;◆are opaque to visible light;◆are hard, rigid;◆can undergo plastic deformation◆have a high melting temperature (Tm).Organic polymers:◆made up of long-chain molecules;◆are electrical and thermal insulators;◆are light and easily formable;◆the best-known organic polymers are:☐poly (vinyl chloride) (聚氯乙烯，PVC);☐polyethylene (聚乙烯，PE);☐polystyrene (聚苯乙烯，PS)。

Composite materials: Are constituted by two or more different materials with specific properties.➢Glass fiber reinforced resins:lightweight composites with highmechanical strength➢Concrete:an agglomeration of cement, sandand gravelMechanical properties:☐The behavior of materials deformed by a set of forces.☐弹性Elasticity☐塑性Plasticity☐强度Strength☐硬度Hardness☐韧性Toughness☐疲劳特性Fatigue behavior☐耐磨性Abrasion resistancePhysical properties:◆The behavior of materials subjected to the action of temperature, electric ormagnetic fields, or light.☐电性能Electric properties☐磁性能Magnetic properties☐热性能Thermal properties☐光性能Optical propertiesChemical properties:◆The behavior of material in a reactive environment.◆抗腐蚀能力Corrosion resistance☐Atmospherically,☐Chemically (salts, acid, alkali)Materials Engineering:◆Concerned with☐Manufacturing,☐Transformation☐Shaping☐Processing.The three most common crystal structures of metals are☐Body-centered cubic structure,☐Face-centered cubic structure,☐Hexagonal close-packed structureProduction of steel:◆Pig iron contains too much carbon and too many impurities to be used directly inmost applications.◆It must be converted to steel in one of several types of converters. Theseconverters may differ in appearance, but they do the same thing:☐burn off the carbon in the iron.☐Impurities are removed as gases and in the slag.☐Phosphorus and sulfur are reduced to less than 0.05 percent of the steel.☐Manganese content is reduced to an amount from 0.2 to 2.0 percent;☐Silicon is reduced to an amount from 0.01 to 3.5 percent.Three primary ores are☐magnetite,☐hematite,☐taconite铸铁概念：cast iron, essentially an alloy of iron, carbon and silicon, is composed of iron and from 2 to 6.67 percent carbon, plus manganese, sulfur, and phosphorus, and shaped by being cast in a mold.The types and properties of cast iron ；white cast iron( hard , brittle ) , gray cast iron (brittle ,withstand large compressive loads but small tensile loads ), alloy cast iron , nodular or ductile cast iron (good castability ,toughness, good wear resistance ,low meltingpoint ,and hardenability ), malleable cast iron (strength ,toughness, ductility ,and machinability)Stainless Steel :●Ferritic●Martensitic●Austenitic●PH Alloysadvantages of using Al:one-third of the weight of steel ;good thermal and electrical conductivity ;high strength-to-weight ratio ;can be given a hard surface by anodizing and hard coating ;most alloys are weldable ;will not rust ;high reflectivity ;can be die cast ;easily machined ;good formability; nonmagnetic ;nontoxic and one –third of the stiffness of steel.Magnesium:1.The lightest of all structural metals2.Specific gravity:1.753. Magnesium weighs 1.5 times less than an equal volume of aluminum and 4 times less than zinc.4.High strength, stiffness, dimensional stability,5.High strength-to-weight ratio. Magnesium alloys have☐relatively high thermal and electrical conductivities;☐good energy absorption characteristics;☐Nonmagnetic propertiesThe four types of stresses:ductility, tensile strength, proportional limit, elastic limit, modulus of elasticity, resilience, yield point, yield strength, ultimate strength, and breaking strengthFour basic types of stresses : tensile, compressive, shear ,torsion (拉力，压力，剪切力，扭转力)Metals and nonmetals◆Ability to donate electrons and form a positive ion;◆Crystalline structure – grain structure;◆High thermal and electrical conductivity;◆Ability to be deformed plastically, and◆Metallic luster or reflectivityCrystalline unit structures◆Body-centered cubic (BCC)◆Face-centered cubic (FCC)◆Hexagonal close-packed (HCP)◆Cubic◆Body-centered tetragonal◆RhombohedralThere are several factors that may speed the corrosion process. Among these factors are ☐an increase in temperature,☐the presence of certain gases,☐environmental factors such as acid rain,☐metal fatigue,☐cold working/forming,☐and other similar factorsCeramic compounds:Can be defined as inorganic compounds made by heating clay or other mineral matter to a high temperature at which they partially melt and bond together Ceramics Classification☐traditional ceramics: derived and processed from clay or nonclay minerals including refractories（耐火材料), white wares, cement(水泥), porcelain(瓷器), and structural clay ceramics.☐advanced ceramics: high purity, better mechanical, electrical, magnetic, and optical propertiesNature of Ceramics◆Crystalline solids composed of metallic and nonmetallic materials◆Ceramics are crystal structures made of metallic ions and Inorganic materials◆Bonding is either partially or completely ionic.◆Variables include☐The magnitude of the electrical charge on the ions;☐The relative size of the ionsProperties of Ceramics◆Corrosion resistance, chemical inertness, thermal shock resistance wear-resistance◆Electrical properties: solid electrolytes in experimental batteries and fuel cells◆Other uses: include automotive sensors, packaging for integrated circuits,electronic/optical devices, fiber optics, microchips, and magnetic headsPorosity and Density◆Mass density, which uses the mass of a material divided by its volume refers to thistheoretical density◆Atomic weight is a major factor in determining the density of a material◆Close-packed metals are more dense than open-structured material s◆The optimum density of spherical particles can be reached by varying the sizedistribution of particles to permit smaller particles (50 nm or less) to locate in the interstices (空隙) of the larger ones.Ceramic Processing◆Traditional Processing☐structural clay products and the whitewares.☐Formation → Drying →Firing◆Advanced Ceramic Processing1.制备工艺：不再以熔炉为主要烧结工具, 如真空烧结、气氛烧结、热压烧结、气压烧结等。