Quantitative Evaluation of residual life of heat-resistant alloy under random creep-fatigue loadings at elevated temperature

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01205
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Tohoku University
• Principal Investigator: Miura Hideo 東北大学, 工学研究科, 教授 (90361112)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 高温強度 / クリープ疲労損傷 / 原子配列の秩序性 / 電子線後方散乱回折 / 粒界割れ

Outline of Final Research Achievements

The acceleration mechanism of the creep-fatigue damage of heat-resistant alloys under harsh condition at elevated temperature was quantitatively clarified from the viewpoint of strain-induced anisotropic diffusion of atoms and vacancies. Accumulation process of vacancies around grain boundaries and heterointerfaces was explained by the modified Arrhenius equation by considering the local decrease in the activation energy of the self-diffusion of component elements. The diffusion and accumulation of vacancies was found to be drastically accelerated by the local strain. The accumulation was quantitatively related to the orderliness of atomic alignment and thus, the strength of grain boundaries and thus, lifetime of intergranular cracking was successfully predicted.

Free Research Field

材料強度科学

Academic Significance and Societal Importance of the Research Achievements

本研究により，耐熱合金の破壊機構が負荷条件により延性的結晶粒内破壊から脆性的結晶粒界割れに移行するメカニズムが定量的に解明され，構造の破壊を加速する粒界割れの発現を定量的に予測可能となったことは学術分野だけでなく産業における実機の信頼性設計や維持管理に大きく貢献するものと考えている．歪み誘起の異常増速拡散現象に基づく原子空孔の発生・集積から粒界割れに至る過程を定量的に解析する手法の開発が独創的な研究であることは米国機械学会賞受賞初め国内外の学会から高く評価されている．