Coherent Phase Diagram of Au-Cu-Pt Ternary System by High Resolution Electron Microscopy

根据艾伦和卡恩的假设，主要用透射电镜明场、暗场成象和选区电子衍射技术测定了AuCu-Pt赝二元系的非相干相图。因为相干相图给了我们更有效的信息来预测与年龄相关的相变，合金系统的硬化特性比平衡相图。在本实验中发现下列相区：（1）面心立方无序固溶体α_0单相区，（2）AuCu I（L1_0）fct有序单相区，（3）长周期正交超结构AuCu II（<0-S>L1_0）单相区，（4）α + AuCu I两相共存区;（5）两个共存相的AuCu I + AuCu II区：（6）三个共存相的α + AuCu I + AuCu II区。

Acoherent phase diagram of the AuCu-Pt pseudobinary system was determined mainly by means of TEM bright- and dark-field imaging and selected area electron diffraction techniques according to the hypothesis of Allen and Cahn, because a coherent phase diagram gives us more effective information to predict phase transformations related to age-hardening characteristics in an alloy system than an equilibrium phase diagram.The following phase regions were found in the present experiments ; (1) alpha_0 single-phase of fcc disordered solid solution region ; (2) AuCu I(L1_0)fct ordered single-phase region ; (3) long-period orthorhombic superstructure AuCu II(L1_<0-S>)single-phase region ; (4) alpha + AuCu I region of two coexisting phases ; (5) AuCu I + AuCu II region of two coexisting phases ; (6) alpha + AuCu I + AuCu II region of three coexisting phases.