机械工程材料第八版第二章课件（一）（中英双文）.ppt

Frequent crystal orientations of cubic crystal systems are: 立方晶系常见的晶向为： 111 [111] [111] [111] [111] X Z Y Instructions: ① in a cubic crystal system, crystal plane and crystal orientation with the same index are vertical to each other. ② “-” should be set on top of the negative index. - - ③ crystal orientations are directional, for example, [110] and [110] are opposite to each other. X Z Y (221) [221] [110] [110] 说明： ① 在立方晶系中，指数相同的晶面与晶向相互垂直。 ② 遇到负指数，“-”号放在该指数的上方。 - - ③ 晶向具有方向性， 如[110]与[110]方 向相反。 X Z Y (221) [221] [110] [110] * * * * * * * * * * * * * * 2 Structures of Materials The substance is made up of atoms. The combination and arrangement of atoms determine properties of the substance. Binding forces among atoms, ions and molecules are called bonds. Their combination status is called structure. C60 第二章 材料的结构 物质由原子组成。原子的结合方式和排列方式决定了物质的性能。 原子、离子、分子之间的结合力称为结合键。它们的具体组合状态称为结构。 C60 2.1 Crystal Structure of Metals and Crystallization 2.1.1 Crystals and Non-crystals Crystals: Atoms are arranged regularly in solid state. Metals exist in the form of crystals under normal conditions. Crystals are anisotropic. Non-crystals: Atoms are arranged in disorder in solid state. Crystals and non-crystals could convert into each other certain circumstances. Isotropic 金属的结构 晶态 非晶态 SiO2的结构 一、晶体结构的基本概念 1、晶体与非晶体 晶体是指原子呈规则排列的固体。常态下金属主要以晶体形式存在。晶体具有各向异性。 非晶体是指原子呈无序排列的固体。在一定条件下晶体和非晶体可互相转化。 金属的结构 晶态 非晶态 SiO2的结构 2.1.2 Crystal lattice and crystal cell ⑴ crystal lattice: three-dimensional frameworks by linking center of the atoms with imaginary lines. crossing points of the lines are called nodes. Array formed by the nodes is called space lattice 2、晶格与晶胞 ⑴ 晶格：用假想的直线将原子中心连接起来所形成。 的三维空间格架。直线的交点（原子中心）称结点。由结点形成的空间点的阵列称空间点阵 ⑵ Crystal cell: the smallest geometric unit that could represent atom range regularity. ⑵ 晶胞：能代表晶格原子排列规律的最小几何单元。 ⑷ Crystal system Crystals could be classified into 7 crystal systems basing on the different crystal lattice. More than 90% metal belongs to cubic cry