Physics of Nonlocal Crystalline Plasticity using Meso-scaled testing

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01210
• 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: Osaka University
• Principal Investigator: Shibutani Yoji 大阪大学, 大学院工学研究科, 教授 (70206150)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 粒界を跨ぐすべり / メゾテスティング / 結晶塑性構成式 / Micropolar弾塑性 / 有限要素解析

Outline of Final Research Achievements

This work is related to the grain boundary (GB) modeling by so-called mesoscale testing with micrometer-sized pillars and nanoindentation, and also atomic-scale and crystal plasticity silmulations. Because the role of GB has two aspects; one is strength due to the dislocation pile-up and the other is enhancement of ductility due to the activation of slip transfer across GB. The former mesoscale testing gave us the guideline of selection grain for the parameter determination of crystal plasticity. And also the mechanical behavior of the slip across GB after yielding the slip inside the grain. Based on these experimental facts, the newly proposed crystal plasticity constitutive law with the smooth function of GB index suggests the difference of slip combination and also the newly constructed micropolar elastic-plastic constitutive law provided the relaxation of strain localization near the interface.

Free Research Field

固体力学

Academic Significance and Societal Importance of the Research Achievements

本研究で得られた粒界を跨ぐすべりの知見は，世界的には数少ない観察事例になっている．加えて，その力学的な応答を精度よく取得し，従来の臨界分解せん断応力に加えて，粒界を跨ぐすべりの臨界応力が新たに取得できた．このことは，従来の強度の増加は延性の低下を導き，その逆の関係にもある金属材料のトレードオフを打開する貴重な知見になる．すなわち，加工硬化と伸びのバランスを制御するために，転位の堆積と粒界を跨ぐ塑性の活性化が重要な鍵になることが新たにわかった．また，原子論的特性をMicropolar体の付加自由度で表現することにより，トップダウン形式のマルチスケールモデリングの可能性が新たに示唆された．