南京航空航天大学《材料科学基础》2-3合金相的晶体结构2.ppt
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§2-3 参考书 胡赓祥 等,金属学,上海科学技术出版社,1980 包永千,金属学基础,冶金工业出版社,1986 卢光熙 等,金属学教程,上海科学技术出版社,1985 潘金生 等,材料科学基础,清华大学出版社,1995 §2-3合金相的晶体结构 1. 概述 2. 固溶体 3. 化合物 4. 合金相的结构符号 1. 概 述 1.1 合金化的目的 1.2 基本概念 1.1 合金化的目的 纯金属因性能有一定的局限性,故应用范围受到了限制 合金化是提高纯金属性能的最主要的途径 Most pure metals are soft and not very useful in their pure state. Therefore in order to increase properties like strength, hardness and corrosion resistance we mix two or more pure metals together to give us an alloy. Everyday examples of alloys include Bronze which is an alloy of Copper and Tin where the Tin content is usually less than 20%. 合金化举例 1.2 基本概念 1.2.1 合金 1.2.2 组元 1.2.3 合金相 1.2.5 组织 1.2.6 合金相的分类 Strength The main contributions to the strength of a steel come from: These factors are controlled by the chemistry of the steel and the processing route used to produce the final component. All of these aspects need to be taken into account when selecting or designing a steel for a given application. For ferrite and pearlite steels relationships between yield /tensile strength and various compositional and microstructural factors have been developed. These are useful in that they show general characteristics, although they are unable to incorporate all factors that influence strength in modern steels, for example precipitation strengthening. Examples of these relationships are given below: YS (MPa) = 53.9 + 32.3 Mn + 83.2 Si + 354 Nf + 17.4 d-1/2 UTS (MPa) = 294 + 27.7 Mn + 83.2 Si + 3.85 pearlite % + 7.7 d-1/2 Alloying addition in wt%, d is the ferrite grain size in mm, Nf is the free nitrogen content? Rolling The most widely used forming process in which the thickness of a material is reduced by passing between two rolls. Hot-rolling is used for larger amounts of deformation. Cold-rolling is used to optimize the mechanical properties and surface finish. Annealing A heat treatment designed to soften a metal or alloy. Annealing is associated with recovery, recrystallisation and/or grain growth.
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