Grain refinement and plasma electrolytic oxidation of a Mg–Zn–Zr–Ce alloy: a synergistic approach to enhancing mechanical properties and stress-corrosion cracking resistance

• Published in: Journal of materials science Vol. 60; no. 28; pp. 12013 - 12041
• Main Authors: Kashin, Alexander, Prosolov, Konstantin, Eroshenko, Anna, Sedelnikova, Maria, Luginin, Nikita, Khimich, Margarita, Gnedenkov, Andrey, Sinebryukhov, Sergey, Nomerovskii, Alexey, Marchenko, Valeriia, Gnedenkov, Sergey, Sharkeev, Yurii
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2025; Springer Nature B.V
• Subjects: Biodegradation; Calcium phosphates; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Coatings; Corrosion resistance; Crystallites; Crystallography and Scattering Methods; Deformation; Grain refinement; Grain size; Hydroxyapatite; Magnesium base alloys; Materials Science; Mechanical properties; Metals & Corrosion; Methods; Oxidation; Periclase; Phosphate coatings; Physiology; Plastic deformation; Polymer Sciences; Service life; Solid Mechanics; Stress corrosion cracking; Strontium; Structural analysis; Substrates; Tensile strength; Titanium alloys; Transplants & implants; Ultrafines; Zinc; Zirconium
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-025-11061-8

This study explores the effect of surface modification of the Mg–Zn–Zr–Ce alloy in three structural states with varying degrees of grain refinement: coarse-grained, fine-grained, and ultrafine-grained (UFG) structures. To modify the surface, Sr-doped calcium phosphate coatings were deposited on magnesium (Mg) substrates via plasma electrolytic oxidation (PEO). This is especially relevant given the rapid dissolution rate of Mg, its insufficient mechanical properties and ambiguous behavior under the conditions of stress-corrosion cracking (SCC), a subject that has received sparse research attention. Our findings during the study indicate that the coatings maintained consistent structural and elemental properties upon substrate grain refinement. In the case of coated FG and UFG Mg substrates, phases of α-tricalcium phosphate (α-TCP), β-tricalcium phosphate (β-TCP), and periclase (MgO) were identified, with tricalcium phosphate (TCP) and hydroxyapatite crystallites visible in the coatings structure. A comprehensive structural characterization allowed us to conclude that grain refinement results in higher adhesion strength of the coatings and overall corrosion resistance of the studied samples. The SCC studies of the samples revealed that the UFG sample of the Mg–Zr–Zn–Ce alloy modified with PEO coating exhibited the highest resistance to corrosion cracking in a 0.9% NaCl solution under static loading conditions. It can be inferred that the combination of severe plastic deformation and Sr-doped calcium phosphate coatings could potentially lead to a significant improvement in the service life and operational characteristics of Mg-based implants.