3-2金属材料的结构和组成Chapter 3Composition and Structure of Metallic Materials3-2-1金属材料1：原子结构Atomic structure of metals轨道上价电子，价电子数少（1一2个）1且与原子核的结合的结合力弱很容易脱离核，而成为自由电子。Metallic bonding:ion cores④正离子·自由电子electroncloud(sea ofelectrons
3-2金属材料的结构和组成 Composition and Structure of Metallic Materials 3-2-1金属材料 1． 原子结构 Atomic structure of metals 轨道上价电子，价电子 数少（1—2个），且与原 子核的结合的结合力弱， 很容易脱离核，而成为自 由电子。 Metallic bonding: ion cores electron cloud(sea of electrons) Chapter 3
2.金属晶体结构Clystal Structures of Metals（1）随温度变化（2）室温下有三种：体心立方结构面心立方密堆六方较高强度、硬度和熔具有良好塑性强度低，塑点但塑性和韧性差和韧性性和韧性差Li, Na, K(S1) Au, Ag, Cu(d10sl) Mg, Ti, Zr(d2s2)Ni,Pd, Pt (d8s2) Cr, Mo, W (d5s1)晶胞内原子数246点阵常数4R/34R/2
2. 金属晶体结构 Clystal Structures of Metals （1）随温度变化 （2）室温下有三种： 体心立方结构 面心立方 密堆六方 较高强度、硬度和熔 具有良好塑性 强度低，塑 点但塑性和韧性差 和韧性 性和韧性差 Li, Na, K(S1) Au, Ag, Cu(d10s1) Mg, Ti, Zr(d2s2) Ni,Pd, Pt (d8s2) Cr, Mo, W (d5s1) 晶胞内 原子数 2 4 6 点阵常数 4R/ 3 4R/ 2 ——
元素晶体结构点阵常数最近的原子间距ac铝镀铜铬钻铜金铁铅锂镁钥镍锯铂钾锈钢银钠针钛钨铀钒锌锆面心立方4.04962.863密排六方3.58322.2252.2856密排六方2.9792.97885.6167体心立方2.4982.8846密排六方2.4972.5064.069面心立方3.61472.556面心立方4.07882.884体心立方2.86642.481面心立方4.95023.500体心立方3.50923.039密排立方3.20945.21053.197体心立方3.14682.725面心立方3.52362.492体心立方3.30072.858面心立方3.92392.775体心立方4.6275.3444面心立方3.80442.690体心立方5.69854.882.889面心立方4.0857体心立方4.29063.716体心立方3.30262.860面心立方5.08433.595密排六方2.95064.67882.890体心立方3.16502.741正交2.77体心立方3.02822.622密排六方2.66494.94682.665密排六方3.23125.14773.172
元素 晶体结构 点阵常数 最近的原子间距 a c 铝铍镉铬钴铜金铁铅锂镁钼镍铌铂钾铑铷银钠钽钍钛钨铀钒锌锆 面心立方 密排六方 密排六方 体心立方 密排六方 面心立方 面心立方 体心立方 面心立方 体心立方 密排立方 体心立方 面心立方 体心立方 面心立方 体心立方 面心立方 体心立方 面心立方 体心立方 体心立方 面心立方 密排六方 体心立方 正交 体心立方 密排六方 密排六方 4.0496 2.2856 2.9788 2.8846 2.506 3.6147 4.0788 2.8664 4.9502 3.5092 3.2094 3.1468 3.5236 3.3007 3.9239 5.3444 3.8044 5.6985 4.0857 4.2906 3.3026 5.0843 2.9506 3.1650 3.0282 2.6649 3.2312 3.5832 5.6167 4.069 5.2105 4.6788 4.9468 5.1477 2.863 2.225 2.979 2.498 2.497 2.556 2.884 2.481 3.500 3.039 3.197 2.725 2.492 2.858 2.775 4.627 2.690 4.88 2.889 3.716 2.860 3.595 2.890 2.741 2.77 2.622 2.665 3.172
Table 3.1AtomicAtomicCrystalRadiusbRadiusCrystalMetal(nm)Metal(nm)StructureaStructureFCCBCC0.14310.1363AluminumMolybdenumHCPFCC0.1490Nickel0.1246CadmiumBCCFCC0.12490.1387ChromiumPlatinumFCCCobaltHCP0.1253Silver0.1445FCCBCC0.12780.1430CopperTantalumGoldFCCHCP0.14450.1442Titanium (α)BCCBCC0.12410.1371Iron (α)TungstenFCCLeadZincHCP0.13320.1750
Table 3.1
EXAMPLEPROBLEM3.3Copper has an atomic radius of 0.128 nm (1.28 A ), an FCCcrystal structure, and an atomic weight of 63.5 g/mol. Compute itstheoretical density and compare the answer withits measureddensity.SOLUTIONnAcunAcupVeNA(16R3V2)NA(4atoms/unitcell)(63.5g/mol)[16 V2(1.28 × 10-8cm)3/unit cell](6.023× 1023atoms/mol)= 8.89g/cm3The literature value for the density of copper is 8.94 g/cm 3
EXAMPLE PROBLEM 3.3 Copper has an atomic radius of 0.128 nm (1.28 A °), an FCC crystal structure, and an atomic weight of 63.5 g/mol. Compute its theoretical density and compare the answer with its measured density. SOLUTION The literature value for the density of copper is 8.94 g/cm 3