Research

1. 金属材料の塑性変形（繰り返し変形，巨大ひずみ加工等）や熱処理によって形成される内部組織と，それらによってもたらされる機械的/機能的特性の関連性について研究を行っています．電視顕微鏡法や各種力学特性試験といった実験的手法と，転位論や速度論等の理論的手法を駆使して，組織と特性の関係（Structure-Property relationship）を明らかにしようと挑戦しています．

The main interest of the research is the relationship between the microstructure produced by plastic deformation (cyclic deformation, severe plastic deformation, etc.) and/or heat treatment of metallic materials, and the mechanical/functional properties brought about by them. We are trying to clarify the relationship between microstructure and characteristics (Structure – Property relationship) by using both the experimental methods such as microstructure observations and various tests of mechanical properties, and theoretical methods such as dislocation theory and kinetic theory.

材料強度学，材料組織学，転位論，成長速度論，組織制御

1. “Strain-Rate and Temperature Dependences of Deformation Behavior of AZ61Mg Alloy Processed by Multi-directional Forging Under Decreasing Temperature Conditions”,
   C. Watanabe, R. Monzen, R. Ueji and H. Miura: Metallurgical and Materials Transactions A 48 (2017) pp. 5368-5375.
2. “Effects of Small Addition of Ti on Strength and Microstructure of a Cu-Ni-Si Alloy”,
   C. Watanabe, S. Takeshita and R. Monzen: Metallurgical and Materials Transactions A 46 (2015) pp. 2469-2475.
3. “Misfit Strains of Precipitated Phases and Dimensional Changes in Cu-Be Alloys”,
   C. Watanabe, T. Sakai and R. Monzen: Philosophical Magazine 88 (2008) pp. 1401-1410.
4. “Effects of Al3Sc Particle Size and Precipitate-Free Zones on Fatigue Behavior and Dislocation Structure of an Aged Al-Mg-Sc Alloy”,
   C. Watanabe, R. Monzen and K. Tazaki: International Journal of Fatigue 30 (2008) pp. 635-641.
5. “Coarsening of Al3Sc Precipitate Particles in an Al-0.28 wt pct Sc Alloy”,
   C. Watanabe, K. Kondo and R. Monzen: Metallurgical and Materials Transactions A 35 (2004) pp. 3003-3008.

1. 金属の結晶欠陥（結晶粒界，積層欠陥，転位など）を制御することによって，材料の強度を向上させる研究を行っています．最近は特に種々の固溶体合金の超微細結晶粒材料に焦点をあてて研究しており，また多元系固溶体合金も研究対象にしています．
2. 鋳造，粉体焼結，レーザ加工等の材料加工法で，種々の金属基複合材料（金属とセラミックスで構成される材料）を作製し，これらの材料特性の評価や応用に関する研究を行っています．最近は特にレーザによる附加製造（Additive Manufacturing: AM）で積層造形した複合材料に興味を持ち，研究を行っています．

金属物理学，材料強度学，材料組織学，材料創製・加工，超微細粒材料，巨大ひずみ加工，複合材料，傾斜機能材料，鋳造，粉体焼結，Additive Manufacturing (AM)

1. “Drilling CFRP Laminates by Dual-Axis Grinding Wheel System with Copper/Diamond Functionally Graded Grinding Wheel”,
   T. Kunimine, H. Tsuge, D. Ogawa, M. Yamada, H. Sato and Y. Watanabe: Journal of Manufacturing Science and Engineering-Transactions of the ASME 140 (2018) 071011.
2. “Fabrication of Copper/Diamond Functionally Graded Materials for Grinding Wheels by Centrifugal Sintered-Casting”,
   T. Kunimine, M. Shibuya, H. Sato and Y. Watanabe: Journal of Materials Processing Technology 217 (2015) pp. 294-301.
3. “Inverse Temperature Dependence of Activation Volume in Ultrafine-Grained Copper Processed by Accumulative Roll-Bonding”,
   T. Kunimine, T. Aragaki, T. Fujii, S. Onaka and M. Kato: Journal of Materials Science 46 (2011) pp. 4302-4307.
4. “Effects of Si Addition on Mechanical Properties of Copper Severely Deformed by Accumulative Roll-Bonding”,
   T. Kunimine, T. Fujii, S. Onaka, N. Tsuji and M. Kato: Journal of Materials Science 46 (2011) pp. 4290-4295.
5. “Temperature and Strain Rate Dependence of Flow Stress in Severely Deformed Copper by Accumulative Roll Bonding”,
   T. Kunimine, N. Takata, N. Tsuji, T. Fujii, M. Kato and S. Onaka: Materials Transactions 50 (2009) pp. 64-69.

1. 金属材料の不均一変形と金属組織，機械的性質の関係について研究を行っています．金属は巨視的には均一な変形を起こしていてもメゾ・ミクロスケールでは不均一に変形が進行していることが分かってきています．それらの変形挙動を生み出す本質的な要因と機械的性質に及ぼす影響を明らかとすることで，新たな材料開発へと発展させていくことを目標としております．

材料組織学，鉄鋼材料，材料強度学，組織制御，変形・破壊

1. “Tensile properties and deformation behavior of ferrite and austenite duplex stainless steel at cryogenic temperatures”,
   N. Koga, T. Nameki, O. Umezawa, V. Tschan, K.P. Weiss, Mater. Sci. Eng. A., 801(2021) 140442.
2. “Low-temperature tensile properties of Cu-Fe laminated sheets with various number of layers”,
   N. Koga, S. Tomono, O. Umezawa, Mater. Sci. Eng. A., 811(2021) 141066.
3. “Strain distribution and deformation-induced martensitic transformation in tension for a TRIP steel plate”,
   N. Koga,  T. Yamashita, O. Umezawa, ISIJ Int., 60(2021) 2083-2089.
4. “Crack initiation and propagation behavior in γ’-Fe₄N layer during monotonic and cyclic deformation in nitrided ultra-low carbon steel”,
   N. Koga S. Saito, O. Umezawa, J. Mater. Sci., 57(2022) 2194-2207.
5. “Distribution of elastic strain in a pearlite structure”,
   N. Koga, N. Nakada, T. Tsuchiyama, S. Takaki, M. Ojima and Y. Adachi: Scripta Materialia 67 (2012) pp. 400-403.

2021M-217 パーライト鋼のラメラ配向制御法の確立と超高強度-高延性化 補助事業　研究成果