Chun Feng, Jianjuan Yin, Jian-Gang Niu, Qinghua Zhang, Lin Gu, Feng Yang, Xiaolei Tang, Longxiang Xu, Kui Gong, Yi Cao, Meiyin Yang, Xiaopeng Cui, Shigenobu Ogata, Wen-Tong Geng, and Guanghua Yu, "Construction of FeN alloy films with ultra-strong magnetism and tunable magnetic anisotropy for spintronic application", Journal of Alloys and Compounds, 725 (2017) 32-40.
FeN alloy film is a promising spintronic material with the theoretically ultra-strong magnetism (saturation magnetization MS and magnetic anisotropy Keff) and high spin polarization, which relies on the degree of N ordering interstice occupancy (S). However, due to the high activation energy for N ordering, the S value of an actual FeN film is mostly lower than 35% and this restricts the achievable magnetism and transportation property. Thus, the construction of a FeN alloy film with well-controlled magnetism and efficient electronic transportation remains a long-standing challenge. Here, we tackle the problem by strain engineering. Using an Fe/Cr underlayer, we introduced a considerable epitaxial strain in the FeN lattice. The strain is proven to effectively promote the S value to over 60%, resulting in remarkable enhancement of MS value from 2.18T to 2.81T (30% increment) and effective tunability of Keff value ranging 1.3~2.2 × 106 J/m3. Besides, the matched energy band symmetry (Δ5) between Cr and Fe16N2 facilitates the efficient electronic transportation for spintronic applications. By simulating interstice distribution with the first-principles calculations, the lattice strain is found to decrease the activation energy for N interstitial migration, which serves as a thermodynamic driving force for the magnetism tunability.
Ryo Matsumoto, Takahiro Chida, and Shinji Hahami, "Indentation Joining Process with Bar Oscillation on Servo-controlled Press―Development of Plastic Joining Method Using Indentation III ―", The Japan Society for Technology of Plasticity, 51-593 (2010) 597-601. [in Japanese]
A plastic joining method for fixing bars with a hot-forged plate was proposed in previous papers. In this method, a cold bar is directly indented into a hot plate to pierce the plate without lubrication on a press and then fixed to the plate after piercing. In this study, to improve the bonding strength of a bar-plate, the indented bar was oscillated at amplitudes of 0.2 - 2.0 mm immediately after bar indentation into the plate on an AC servo-controlled press. The effect of bar oscillation on the bonding strength of the bar-plate was examined using an A6061 aluminum bar and an A6061 aluminum plate. The obtained shear bonding stress of the bar-plate in the indentation joining with bar oscillation of 0.2 mm of amplitude was approximately 1.5 times higher than that in the indentation joining without bar oscillation at an indentation temperature of 500 °C. The bonding mechanism of the indentation joining with bar oscillation was discussed from the viewpoints of bar-plate seizure and mechanical clam ping associated with the method.
Ryo Matsumoto, Shinji Hanami, Kozo Osakada, and Hyoji Yoshimura, "Indentation Joining Process for Steel Bar - Aluminium Plate ―Development of Plastic Joining Method Using Indentation II―", The Japan Society for Technology of Plasticity, 50-587 (2009) 96-100. [in Japanese]
A new plastic joining method for fixing bars with a hot-forged plate was proposed, in which steel bars maintained at room temperature are directly indented into a high-temperature steel plate, as reported in a previous paper. To examine the validity of the developed plastic joining method, the optimum conditions of the plastic joining method are investigated using an SCM435 steel bar and an A5052 aluminium plate on a mechanical or AC servo-controlled press. It is possible to indent the bar to the plate without the buckling or plastic deformation of the bar at room temperature, and the attained shear bonding stress of the bar–plate is approximately 70% of the shear strength of the plate material. The bonding mechanism of the proposed plastic joining method is discussed from the viewpoints of plate seizure and mechanical clamping associated with the process.
Ryo Matsumoto, Shinji Hanami, A. Ogura, H. Yoshimura, and Kozo Osakada, "New Plastic Joining Method using Indentation of Cold Bar to Hot Forged Part", CIRP Annals - Manufacturing Technology, 57-1 (2008) 279-282.
A new plastic joining method for fixing bars with a hot forged plate is proposed in which bars kept at room temperature are directly indented into a high-temperature plate. The optimum conditions for the proposed plastic joining method are examined using a low-alloyed steel bar and a carbon steel plate. It is possible to indent the bar to the plate without buckling or plastic deformation by keeping the plate above 850 °C. The attained shear bonding stress of bar–plate is approximately 40% of the shear strength of the plate material. The bonding mechanism of the proposed plastic joining method is discussed from the viewpoints of seizure of the plate and mechanical clamping associated with the process. Furthermore, some applications of the proposed method are suggested.