清华大学：《材料科学基础》课程教学资源（PPT课件讲稿）Chapter 2.9 Some Additional Terminology.ppt_大学文库

文档信息

资源类别：文库
文档格式：PPT
文档页数：10
文件大小：683KB
团购合买：点击进入团购

内容简介

1. Sing le crystal ver sus po l crystal 1. For single crystals there is only one type of structure with same orientation Single crystals is characterized by anisotropy 2. Polycrystal consists of a lot of grain, small single crystals, With same structure but different orientations. These small single crystals are called grains. The boundaries between them are called grain boundaries

刷新页面文档预览

32.9 Some Add itional Terminology in Crystal lography 1. Single crystal ver sus polycrystal 1. For single crystals there is only one type of structure with same orientation Single crystals is characterized by anisotropy ov Wl same structure but different orientations. These smal Polycrystal consists of a lot of grain, small single crystals, single crystals are called grains. The boundaries between them are called grain boundaries

§2.9 Some Additional Terminology in Crystallography ◆ Ⅰ. Single crystal versus polycrystal 1. For single crystals there is only one type of structure with same orientation. Single crystals is characterized by anisotropy. 2. Polycrystal consists of a lot of grain, small single crystals, with same structure but different orientations. These small single crystals are called grains. The boundaries between them are called grain boundaries

grain grain boundary single crystal polycrystal

single crystal polycrystal grain grain boundary

◆‖1. Allotropy Same crystal has different crystallographic structure at different condition EXamples: C, graphite, diamond, CNT 910°C 400°C 1540°C a-Fe r-Fe &-Fe q BCC FCC BCC

◆ Ⅱ. Allotropy Same crystal has different crystallographic structure at different condition. Examples: C , graphite , diamond , CNT Liquid 1540 C Fe 1400 C Fe 910 C Fe  −  −   −   BCC FCC BCC