Investigation of correlation between process and phase separation structure of multicomponent alloys and establishment of guideline for new materials process design

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02493
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 27010:Transport phenomena and unit operations-related
• Research Institution: Tohoku University
• Principal Investigator: Tsukada Takao 東北大学, 工学研究科, 教授 (10171969)
• Co-Investigator(Kenkyū-buntansha): 福山 博之 東北大学, 多元物質科学研究所, 教授 (40252259)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 多元系合金 / 融液内対流 / 相分離構造 / 過冷却凝固 / プロセス－構造相関

Outline of Final Research Achievements

The effect of static magnetic filed (i.e., melt convection) on the phase separation structures of undercooled Cu-Co and Cu-Fe alloys solidified under a static magnetic field was clarified using an electromagnetic levitation (EML) technique superimposed with a static magnetic field and neutron CT. By direct numerical simulations of three-dimensional, unsteady magnetohydrodynamic (MHD) convection in a spherical electromagnetically levitated molten Cu-Co droplet under different strengths of the static magnetic field, it was demonstrated that the marked change in phase separation structures in undercooled Cu-Co alloys with increasing the static magnetic filed was closely related to the laminar-turbulent transition of MHD convection in the levitated droplet. The compositional dependence of the thermal conductivity of a molten Cu-Fe alloy at low Fe contents was measured by combining the EML with a static magnetic field and a periodic laser heating method.

Free Research Field

化学工学

Academic Significance and Societal Importance of the Research Achievements

Cu基合金の多くは過冷却域に二液相分離域を有するため，過冷却凝固に伴い二液相分離特有のマクロ，ミクロ凝固組織構造が発現し，その構造に由来した新奇な電気的，磁気的あるいは機械的特性を有する新材料の創製が期待される．本研究は，Cu基合金の相分離構造の制御因子に関し，これまで研究がほとんど行われていなかった融体内対流を制御因子の一つとして捉え，対流構造や強度と相分離構造との関係を実験と理論の両側面から詳細に明らかにした点に学術的意義がある．