材料成形基础 Chapter 10 – Solid Solutions and Phase Equilibrium.ppt

The Science and Engineering of Materials, 4th ed Chapter 10 – Solid Solutions and Phase Equilibrium 机械工程系 吴安如 Objectives of Chapter 10 The goal of this chapter is to describe the underlying physical concepts related to the structure of matter. To examine the relationships between structure of atoms-bonds-properties of engineering materials. Learn about different levels of structure i.e. atomic structure, nanostructure, microstructure, and macrostructure. Chapter Outline 10.1 Phases and the Phase Diagram 10.2 Solubility and Solid Solutions 10.3 Conditions for Unlimited Solid Solubility 10.4 Solid-Solution Strengthening 10.5 Isomorphous Phase Diagrams 10.6 Relationship Between Properties and the Phase Diagram 10.7 Solidification of a Solid-Solution Alloy 10.8 Nonequilibrium Solidification and Segregation Phase - Any portion including the whole of a system, which is physically homogeneous within it and bounded by a surface so that it is mechanically separable from any other portions. Gibbs phase rule - Describes the number of degrees of freedom, or the number of variables that must be fixed to specify the temperature and composition of a phase (2 + C = F + P, where pressure and temperature can change, 1 + C = F + P, where pressure or temperature is constant). P-T diagram - A diagram describing thermodynamic stability of phases under different temperature and pressure conditions (same as a unary phase diagram). 普通黄铜的显微组织 两相的相对重量百分比为： 含碳量对铁碳合金组织和性能的影响 含碳量对室温平衡组织的影响 含碳量与缓冷后相及组织组成物之间的定量关系为： 含碳量对力学性能的影响 亚共析钢随含碳量增加，P 量增加，钢的强度、硬度升高，塑性、韧性下降。 From the phase diagram for the NiO-MgO binary system [Figure 10.10(b)], describe a composition that can melt at 2600oC but will not melt when placed into service at 2300oC. Example 10.5 NiO-MgO Isomorphous System 液相线温度2600℃， 固相线温度2300℃ Example 10.5 SOLUTION To identify a composition with a liquidus temperature below 2600oC, there must be less than 65 mol% MgO in the ref