机械工程材料双语课件2)

1、2.2 Crystal structures of metals,2.2.1 Crystal structures of pure metals Metal atoms are combined by the interaction between the positive ions and the free electrons, named metallic bonds. Metals tend to array tightly.,Metals have good thermal conductivity, electric conductivity, ductility and metal

2、lic brightness. The common crystal lattice type of pure metals are body centered cubic (bcc), face centered cubic (fcc), and close-packed hexagonal.,二、金属的晶体结构,1、纯金属的晶体结构 金属原子是通过正离子与自由电子的相互作用而结合的，称为金属键。 金属原子趋向于紧密排列。,具有良好的导热性、导电性、延展性及金属光泽。 常见纯金属的晶格类型有体心立方(bcc)、面心立方(fcc)和密排六方(hcp)晶格。, Body centered cub

3、ic crystal lattice,Body centered cubic crystal lattice,Parameters for body centered cubic crystal lattice,Body centered cubic crystal lattice,Atomicity: 2 Coordination number: 8 Tightness: 0.68 Frequent metals: -Fe, Cr, W, Mo, V, Nb, etc.,Crystal lattice constants: a(a=b=c),Atom radius:,体心立方晶格,原子个数：

4、2 配位数： 8 致密度：0.68 常见金属：-Fe、Cr、W、Mo、V、Nb等,晶格常数：a(a=b=c),原子半径：, Face centered cubic crystal lattice,Faced centered cubic crystal lattice,Parameters for face centered cubic crystal lattice,Atomicity: 4 Coordinate number: 12 Tightness: 0.74 Frequent metals: -Fe, Ni, A l, Cu, Pb, Au, etc.,Crystal lattice

5、 constant: a,Face centered cubic crystal lattice,原子个数：4 配位数： 12 致密度：0.74 常见金属： -Fe、Ni、Al、Cu、Pb、Au等,晶格常数：a,面心立方晶格, Closed-packed hexagonal crystal lattice,Parameters for closed-packed hexagonal crystal lattice,Atomicity: 6 Coordinate number: 12 Tightness: 0.74 Frequent metals: Mg, Zn, Be, Cd, etc.,Cr

6、ystal lattice constant: side length of base face a and c, c/a=1.633,Closed-packed hexagonal crystal lattice,原子个数：6 配位数： 12 致密度：0.74 常见金属： Mg、Zn、 Be、Cd等,晶格常数：底面边长 a 和高 c， c/a=1.633,密排六方晶格, closed-packed planes and orientations of the three ordinary crystal lattices Atomicity on unit area of the cryst

7、al plane is called crystal plane atomic density. Atomicity on unit length of the crystal orientation is called crystal orientation atomic density. The crystal plane or crystal orientation with the largest atomic density is called closed packed plane or closed packed orientation., 三种常见晶格的密排面和密排方向 单位面

8、积晶面上的原子数称晶面原子密度。 单位长度晶向上的原子数称晶向原子密度。 原子密度最大的晶面或晶向称密排面或密排方向。,closed-packed planes and orientations of the three ordinary crystal lattices,三种常见晶格的密排面和密排方向,Stack sequence of the closed-packed plane in face centered cubic crystal lattice and closed-packed hexagonal crystal lattice Stack sequence of closed-packed hexagonal crystal lattice is ABABAB Stack sequence of face centered cubic crystal lattice is ABCA