Elucidation of mechanism for semi-solid deformation causing dilatancy

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H04546
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Metal making/Resorce production engineering
• Research Institution: Osaka University
• Principal Investigator: Nagira Tomoya 大阪大学, 接合科学研究所, 准教授 (00379124)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 鋳造欠陥 / その場観察 / せん断変形 / ダイラタンシー / 放射光 / 固液共存体

Outline of Final Research Achievements

Synchrotron X-ray radiography was used to study tensile and compressive deformations of semi solid Al-Cu and Fe-C alloys. In the case of tensile deformation of Al-Cu sample, tensile deformation was localized in the high strain region, resulting in the formation of internal cracking in the plane normal to the tensile axis. On the other hand, in the case of compressive deformations of Al-Cu and Fe-C samples, rearrangement of solid particles including translation and rotation caused the shear induced dilation at the shear domains. Shear fracture finally occurred due to inadequate liquid flow into the expanding spaces between solid particles caused by shear-induced dilation. The solid/solid interaction including impingement between solid particles and rearrangement has significant role in the compressive deformation. These observations demonstrated that the mechanism of cracking formations induced by compressive deformation was totally different from that in the tensile deformation.

Free Research Field

凝固・結晶成長、溶接・接合

Academic Significance and Societal Importance of the Research Achievements

放射光の高輝度X線を利用して、ダイラタンシー(みかけの体制膨張)が発現する金属合金の固液共存体の特異な変形挙動をミクロンスケールでその場観察することに成功した。圧縮、引張、せん断による変形挙動をそれぞれ調査し、変形モードによって起こる組織変化、欠陥形成機構が大きく異なることを示した。本研究成果は、鋳造欠陥の形成機構の解明だけでなく、固体力学、流体力学とも異なる固液共存体の力学体系の構築にとって学術的な意義がある。また、実際の製造プロセスである連続鋳造法などで発生する鋳造欠陥の抑制にとって有用な知見を与えると期待される。