Stress-corrosion coupled damage localization induced by secondary phases in bio-degradable Mg alloys: phase-field modeling

• Published in: Journal of magnesium and alloys Vol. 12; no. 1; pp. 361 - 383
• Main Authors: Xie, Chao, Bai, Shijie, Liu, Xiao, Zhang, Minghua, Du, Jianke
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2024; KeAi Communications Co., Ltd
• Subjects: Damage localization; Finite element method; Mg alloys; Phase field; Stress-corrosion coupled damage; Finite element method; Stress-corrosion coupled damage; Mg alloys; Damage localization; Phase field
• ISSN: 2213-9567; 2213-9567
• DOI: 10.1016/j.jma.2022.04.004

•A thermodynamically consistent phase-field model is developed for the stress-corrosion coupled damage localization.•A micro-galvanic corrosion domain is defined by imposing the Dirichlet boundary conditions of free corrosion potentials.•Buffering effect of second gradient of electric potential on charge migration is numerically studied.•Some insights into damage localization process and valuable inspiration for damage resistance design of biodegradable Mg alloys are offered. In this study, a phase-field scheme that rigorously obeys conservation laws and irreversible thermodynamics is developed for modeling stress-corrosion coupled damage (SCCD). The coupling constitutive relationships of the deformation, phase-field damage, mass transfer, and electrostatic field are derived from the entropy inequality. The SCCD localization induced by secondary phases in Mg is numerically simulated using the implicit iterative algorithm of the self-defined finite elements. The quantitative evaluation of the SCCD of a C-ring is in good agreement with the experimental results. To capture the damage localization, a micro-galvanic corrosion domain is defined, and the buffering effect on charge migration is explored. Three cases are investigated to reveal the effect of localization on corrosion acceleration and provide guidance for the design for resistance to SCCD at the crystal scale.