The Influence of Trace Elements on High Temperature Intergranular Fracture

本项目旨在确定少量合金添加量对高温蠕变空化和晶间断裂机理的影响。本研究将使用含有微量添加物铈、硼、锆和镁的镍-20%铬合金模型。具体研究目标包括：(1)确定微量元素对高温蠕变流动、空腔形核、晶间断裂和延性的影响；(2)利用内摩擦法确定晶界滑动动力学、机制和应力松弛现象；空腔成核速率和相关参数的测量，特别是表面自由能的测定。结果将与空洞形核、蠕变破裂时间和延性模型进行分析和比较。

This project is designed to determine the effects of small alloying additions on the mechanism of high temperature creep cavitation and intergranular fracture. A model nickel-20% chromium alloy containing trace additions of cerium, boron, zirconium and magnesium will be used in this study. The specific research objectives include: (1) determination of the effects of trace elements on high temperature creep flow, cavity nucleation, intergranular fracture, and ductility; (2) determination of kinetics, mechanisms of grain boundary sliding and of stress relaxation phenomena by means of internal friction; measurement of cavity nucleation rates and associated parameters particularly with determination of surface free energies. The results will be analyzed and compared to models of cavity nucleation, creep rupture time and ductility.