Development of high strength and high corrosion resistant Mg alloys by controlling geometrical and electrochemical heterogeneity

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H03431
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Material processing/Microstructural control engineering
• Research Institution: Kumamoto University
• Principal Investigator: Yamasaki Michiaki 熊本大学, 大学院先端科学研究部(工), 教授 (50343885)
• Co-Investigator(Kenkyū-buntansha): 眞山 剛 熊本大学, 大学院先端科学研究部(工), 准教授 (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, 特任助教 (30792585)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: マグネシウム合金 / 長周期積層構造 / ヘテロ組織 / 腐食防食

Outline of Final Research Achievements

Corrosion and stress corrosion cracking behavior of Mg/LPSO two-phase alloys have been investigated. Multifunctional Mg alloys with LPSO phase have been designed by heterogeneity integration method that considers geometrical and electrochemical viewpoints. (1) Relationship between corrosion behavior and Volta potential difference between alpha-Mg and LPSO phases was clarified. (2) New slow strain rate tensile testing integrated with direct current potential drop method has been developed. Coarse alpha-Mg and LPSO grains with strong fiber-texture are effective for prevention of SCC. (3) Acoustic emission method has been applied to Mg corrosion study. Application of adaptive sequential k-means analysis of AE signal reveled activity of few concurrently active processes during anodic and cathodic polarization measurements. Acoustic emission technique has a potential in corrosion science.

Free Research Field

金属工学

Academic Significance and Societal Importance of the Research Achievements

本研究は，幾何学的な不均一性を意図的に導入することで強度と延性を兼ね備えた長周期積層構造型Mg合金展伸材の腐食・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．この研究の過程でいくつかの腐食研究に有効な新しい手法（低歪み速度引張試験に直流電流電圧変化法を組み合わせたSCC発生応力検知手法やアコースティックエミッション法による腐食素過程探索手法）を取り入れ，これらが腐食・SCC挙動解明に極めて有効であることを明らかにした．これら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．