基于纳米-原子尺度材料微观表征技术的应力腐蚀的位错电化学行为与效应研究

Basing on the analyses of current mainstream models on stress corrosion cracking and the local additional potential model developed in the previous work, this proposal puts forward a unified theory hypothesis on the mechanism of stress corrosion cracking, i.e. the Electrochemical Behavior and its Effect on SCC Mechanism.In order to confirm and perfect this hypothesis, a series of in-situ experimental methods for electrochemical and corrosion morphological study under various loading conditions in nano-atomic scale are going to be explored and established, to systematically investigate the local additional potential effect of dislocations and its role in the mechanism of SCC. The main goal of this project is to develop a unified theory model of the mechanism of SCC, by finding and confirming the of synergistic effect between the outcrop and subsurface structure of dislocations and the localized electrochemical and film failure behavior in nano-atomic scales, and their corresponding role in initiating and expanding of SCC, so as to modify, refine and improve the proposed theory and model. The achievement of this proposal will both provide theoretical support and direct basis for the development of stress corrosion theory and its research methods.

本课题在分析当前主流应力腐蚀机理模型局限性的基础上，基于前期研究所提出的局部附加电位模型，提出了应力腐蚀微观统一机理假说——SCC的位错电化学行为与效应机理假说，拟通过探索并建立应力状态下纳米-原子尺度上的电化学及腐蚀形貌原位实验研究方法，系统研究位错的局部附加电位效应及其在SCC机理中的作用，在纳米-原子尺度上发现并确认SCC萌生及扩展过程中力学-电化学协同效应机制，修正、细化和完善所提出的理论假说，探索建立SCC过程中力学-电化学交互作用的统一机理模型，为应力腐蚀理论与研究方法的发展提供理论支撑与直接参考。

.本课题通过探索建立纳米-原子尺度级的位错电化学及效应的原位或准原位微观机理研究方法，旨在发现应力腐蚀微观机理模型的直接证据，从应力腐蚀微观理论的层面建立SCC过程中力学-电化学交互作用的统一机制模型，为应力腐蚀理论与研究方法的发展提供理论支撑与直接依据。研究取得了如下四点重要进展。（1）建立了多种微观力学-电化学机制的原位研究方法，发现了多种应力腐蚀萌生和扩展的微观新现象和新机制。（2）发现和确认了奥氏体不锈钢和单晶Cu的位错露头具有阴极电化学活性，这是一种应力腐蚀微观电化学的全新机制，对推进应力腐蚀机理发展具有里程碑价值。（3）通过原位实验方法确认了微生物-力学电化学的微观新机制。（4）基于位错-电化学的微观电化学效用，建立了基于位错力学电化学集群效应的应力腐蚀全寿命理论模型。以上研究是应力腐蚀微观电化学机制的重要进展，形成了应力腐蚀统一微观机理模型的理论和实验基础。