Studies on corrosion and stress corrosion cracking of Mg alloys designed by heterogeneous microstructure control

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01673
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: Kumamoto University
• Principal Investigator: Yamasaki Michiaki 熊本大学, 先進マグネシウム国際研究センター, 教授 (50343885)
• Co-Investigator(Kenkyū-buntansha): 眞山 剛 熊本大学, 先端科学研究部, 教授 (40333629) ; 井上 晋一 熊本大学, 先進マグネシウム国際研究センター, 助教 (30792585)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: マグネシウム合金 / 長周期積層構造 / 不均一組織制御 / 腐食防食

Outline of Final Research Achievements

Corrosion and stress corrosion cracking behavior of Mg/LPSO two-phase Mg-Zn-Y alloys were investigated. (1) The crystal orientation dependence of the corrosion behavior of extruded Mg/LPSO two-phase Mg-Zn-Y alloys was clarified. This crystal orientation dependence is significantly affected by the in-plane atomic density of the exposed crystal planes. (2) A method to detect the SCC initiation stress by combining a direct current voltage change method with a slow strain rate tensile test, was developed; the SCC susceptibility and SCC growth rate were estimated. It was found that the LPSO Mg-Zn-Y alloy had a higher SCC susceptibility than the AZ31B alloy, but showed an extremely low SCC growth rate, approximately one-third that of the AZ31B alloy.

Free Research Field

金属工学

Academic Significance and Societal Importance of the Research Achievements

本研究は力学特性を多機能化するために不均一組織制御されたMg合金の腐食挙動とSCC挙動の解明を目指すとともに，新規耐SCC性Mg合金の設計指針を得ることを目的に実施された．幾何学的な不均一性が腐食挙動にどのような影響を及ぼすかを明らかにした点，不均一組織制御により導入された繊維状集合組織加工粒のSCC抑制効果を明らかにした点が研究成果である．この組織不均一性の腐食挙動に与える影響を明確にした基礎的知見は，他の金属系へも展開できることから学術的に重要であり，また防食技術向上への寄与は安全な社会構築に貢献すると考える．