高温合金中复杂结构相的电子显微学新认识

Re-investigation on the complex phases precipitated in superalloys

高温合金由于其成分比较复杂,进而在热处理及服役过程中不可避免地会产生大量的析出相,如碳化物、硼化物、拓扑密堆相等。这些析出相对高温合金的力学性能有重要影响。准确地解析这些析出相的结构与缺陷以及它们与基体间的位向关系、界面特征可以帮助人们更好地理解其从基体中的析出特性,从而控制其析出行为,对高温合金性能产生有益影响。尽管这些复杂结构相在高温合金中普遍存在,但人们对它们的认识仍然停留在前人基于点阵结构的研究结果上。近年来,基于像差校正电子显微术,本课题组对高温合金中的复杂结构相系统地进行了高空间分辨率的结构解析。本文将概述对这些复杂物相的新认识。

Superalloys are usually highly alloyed with many other metallic and non-metallic elements.During the service conditions at high temperature,the supersaturated matrix is usually unstable,which will result in the precipitation of a large number of phases,such as carbides,borides,topologically close-packed phases,and other intermetallic compounds.These precipitates usually have a significant influence on the overall mechanical properties of superalloys.Accurate understanding of the structural characteristics of these precipitates,as well as their orientation relationship and crystallographic features with the matrix,are very helpful for researchers to discuss their precipitation behavior from the matrix and seek ways for the controlled precipitation for improved performance.Despite the widespread presence of these phases in superalloys,our understanding of them still largely relies on early research findings.In recent years,with the flourishing development of aberration-corrected electron microscopy,our research group has made systematic progress in the high-resolution structural characterization of the complex phases in superalloys.This article provides an overview of our new understanding of these complex phases.