High deformability of Mg alloys via dual grain boundary segregation

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05068
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: SOMEKAWA Hidetoshi 国立研究開発法人物質・材料研究機構, 構造材料研究拠点, グループリーダー (50391222)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 材料工学 / マグネシウム / 粒界すべり / 溶質元素 / 偏析 / 粒界構造 / 力学特性

Outline of Final Research Achievements

In order to consider the possibility for high deformability at room-temperature in high strain rate regimens, we examined the correlation between grain boundary structures and plastic deformation behavior using fine-grained Mg ternary alloys produced by several types wrought-processing. Microstructural observations revealed that grain boundary structures could be controlled by the wrought-processing method and types of alloying element. The results obtained from tensile and damping tests showed that the solute atoms which are segregated at grain boundaries affected the major deformation mechanism as well as room temperature ductility. The role of solute atoms on plastic deformation behavior in the present ternary alloys is also found to be the same as those in the binary alloys. The fracture of the alloys having a good deformability is owing to cavitation behavior, which is well-observed in the superplastic materials.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

Mg合金の脆さと乏しい変形能/加工能の改善に関する昨今の主要な取組は、集合組織制御や合金化であり、転位すべり運動制御に基づくものである。本研究では、塑性変形機構に着目し、室温粒界すべりを活性化することで高速・高延性化を図り、Mg固有の問題解決となりうる新規手法を明示した。粒界すべりは、高温下で生じる超塑性で認知されるが、粒界構造を制御した微細結晶粒Mg合金で発現する室温粒界すべり挙動やその破壊様相は、高温下で観察できる従来超塑性材と類似することを特徴とする。