Department of Materials Science and Engineering, Monash University, Clayton, VIC, 3800, Australia.
Materials Genome Institute, Shanghai University, Shanghai, 200072, China.
Sci Rep. 2017 Jun 7;7(1):2961. doi: 10.1038/s41598-017-03090-4.
An empirical model for the evolution of β-phase (MgAl) along grain boundaries in aluminium alloy AA5083 (Al-Mg-Mn) during isothermal exposures is proposed herein. Developing a quantitative understanding of grain boundary precipitation is important to interpreting intergranular corrosion and stress corrosion cracking in this alloy system. To date, complete ab initio models for grain boundary precipitation based upon fundamental principles of thermodynamics and kinetics are not available, despite the critical role that such precipitates play in dictating intergranular corrosion phenomena. Empirical models can therefore serve an important role in advancing the understanding of grain boundary precipitation kinetics, which is an approach applicable beyond the present context. High resolution scanning electron microscopy was to quantify the size and distribution of β-phase precipitates on Ga-embrittled intergranular fracture surfaces of AA5083. The results are compared with the degree of sensitisation (DoS) as judged by nitric acid mass loss testing (ASTM-G67-04), and discussed with models for sensitisation in 5xxx series Al-alloys. The work herein allows sensitisation to be quantified from an unambiguous microstructural perspective.
本文提出了一种用于预测铝合金 AA5083（Al-Mg-Mn）中β相（MgAl）在等温暴露过程中沿晶界演变的经验模型。定量了解晶界沉淀对于解释该合金系统中的晶间腐蚀和应力腐蚀开裂非常重要。迄今为止，尽管这些沉淀物在决定晶间腐蚀现象方面起着至关重要的作用，但基于热力学和动力学基本原理的完整从头算模型还不可用。因此，经验模型可以在推进对晶界沉淀动力学的理解方面发挥重要作用，这是一种适用于超越当前背景的方法。高分辨率扫描电子显微镜用于量化 Ga 脆化 AA5083 晶间断裂表面上β相沉淀物的大小和分布。结果与通过硝酸质量损失测试（ASTM-G67-04）判断的敏化程度（DoS）进行了比较，并与 5xxx 系列 Al 合金的敏化模型进行了讨论。本文的工作允许从明确的微观结构角度量化敏化。
