竹内 章

This paper provides general overviews for the recent progress in alloy designs for high-entropy crystalline and glassy alloys in the following aspects. First, the alloy designs for bulk metallic glasses (BMGs) are briefly reviewed by focusing on atomic size differences, mixing enthalpy and valence electron concentration as well, followed by their extension to the other related alloys including high-entropy alloys (HEAs). Then, the historic backgrounds of the high-entropy bulk metallic glasses (HE-BMGs) are dealt with by pointing out the features of the HE-BMGs. Subsequently, the recently-developed HEAs with hcp structure, which are the new ones to the conventional HEAs with bcc, fcc and their mixture structures, are discussed for their future development. Finally, recent alloy designs utilizing crystallographic data acquired from Pettifor map, Pearson's Crystal Data and binary phase diagrams are discussed in order to use them for the development of new alloys in near future.

This paper reviews past developments and present understanding of the glass-forming ability, structure and physical, chemical, mechanical and magnetic properties of bulk glassy alloys (BGA) with the emphasis on recent results obtained since 1990, together with applications of BGA, achieved mainly in Tohoku University. After introducing the fundamental concepts around glassy alloys (GA) in Sections 1 and 2 describes the progress of the study of structural relaxation leading to the discovery of GA with a large supercooled liquid region. Section 3 reviews the history of BGA development, followed by BGA systems and their features in Section 4, and features of glassy structure in Section 5. Sections 6-9 summarize the engineering and standardization of Zr-based BGA, followed by the origins of the development of useful materials on the basis of experimental data on the compositional effect on the fundamental properties of basic ternary and quaternary Zr-based BGA. Sections 10 and 11 include the glass-forming ability and dynamic mechanical properties of Zr-based hypoeutectic BGA and Cu-Zr-Al-Ag BGA. Mechanical properties of Ni- and Zr-based BGA at low temperatures are shown in Section 12, while Section 13 describes the formation and properties of Ni-free Ti-based BGA. Sections 14 and 15 deal with porous Zr-based BGA, including spherical pores and commercialized ferromagnetic and high-strength Fe-based GA, respectively, then Section 16 reviews supercooled liquid formation. Applications for Zr-, Ti- and Fe-based GA are described in Section 17. In conclusion, Section 18 attempts to assess the present knowledge of the structure and physical properties and identify some outstanding problems for future work. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

This paper reviews past developments and the present understanding of the physical and mechanical properties of glass alloys, with an emphasis on recent results obtained since around 1990, together with applications of bulk glassy alloys achieved mainly in Tohoku University. After introducing the fundamental concepts around glassy alloys in the first section, the second section describes the relationships between structural relaxation and the discoveries of glassy alloys with a large supercooled liquid region. The third section reviews the history of bulk glassy alloy development, followed by the bulk glassy alloy systems and their features in the fourth section and the features of a glassy structure in the fifth section. The sixth, seventh, and eighth sections summarize the engineering and standardization of Zr-based bulk glassy alloys. Section nine and the 10th focus on the glass-forming ability of Zr-based hypoeutectic glassy alloys and Cu-Zr-Al-Ag bulk glassy alloys. The mechanical properties of Ni-based bulk glass alloys at low temperatures are shown in the 11th section, whereas the 12th section describes the formation and properties of Ni-free Ti-based bulk glassy alloys. The 13th and 14th sections deal with porous Zr-based bulk glassy alloys including spherical pores and commercialized Fe-based glassy alloys, respectively, whereas the 15th section reviews supercoold liquid forming. Finally, applications for Zr-, Ti-, and Fe-based glassy alloys are described in the 16th section. In conclusion, the 17th section attempts to assess the present knowledge of the structure and physical properties and identify some outstanding problems for future work.

This paper reviews our recent results of the formation, fundamental properties, workability and applications of late transition metal (LTM) base bulk glassy alloys (BGAs) developed since 1995. The BGAs were obtained in Fe-(Al,Ga)-(P,C,B,Si), Fe-(Cr,Mo)-(C,B), Fe-(Zr,Hf,Nb,Ta)-B, Fe-Ln-B(Ln=lanthanide metal), Fe-B-Si-Nb and Fe-Nd-Al for Fe-based alloys, Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys, Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys, and Cu-Ti-(Zr,Hf), Cu-Al-(Zr,Hf), Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based alloys. These BGAs exhibit useful properties of high mechanical strength, large elastic elongation and high corrosion resistance. In addition, Fe- and Co-based glassy alloys have good soft magnetic properties which cannot be obtained for amorphous and crystalline type magnetic alloys. The Fe- and Ni-based BGAs have already been used in some application fields. These LTM base BGAs are promising as new metallic engineering materials.

This paper reviews our recent results of the formation, fundamental properties, workability and applications of late transition metal (LTM)-based bulk glassy alloys (BGAs) developed since 1995. The BGAs were obtained in Fe-(Al,Ga)-(PC,B,Si), Fe-(Cr,Mo)-(C,B), Fe-(Zr,HfNb,Ta)-B, Fe-Ln-B (Ln=lanthanide metal), Fe-B-Si-Nb and Fe-Nd-Al for Fe-based alloys, Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys, Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys, and Cu-Ti-(ZrHf), Cu-Al-(Zr,Hf), Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based alloys. These BGAs exhibit useful properties of high mechanical strength, large elastic elongation and high corrosion resistance. In addition, Fe- and Co-based glassy alloys have good soft magnetic properties which cannot be obtained for amorphous and crystalline type magnetic alloys. The Fe- and Ni-based BGAs have already been used in some application fields. These LTM-based BGAs are promising as new metallic engineering materials. (c) 2006 Elsevier B.V. All rights reserved.

We review our recent results of the formation, fundamental properties. workability and applications of late transition metal base bulk glassy alloys which have been developed after the first synthesis of Fe-based bulk glassy, alloys by the copper mold casting method in 1995. The late metal transition base bulk glassy alloys were obtained in Fe-(Al,Ga)-(R,C,B,Si). Fe-(Cr,Mo)-(C,B). Fe-(Zr,Hf,N,b.Ta)-B. Fe-Ln-B(Ln = lanthanide metal). Fe-B-Si-Nb and Fe-Nd-Al for Fe-based allovs. Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys. Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys. and Cu-Ti-(Zr,Hf). Cu-Al-(Zr,Hf). Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based alloys. These bulk glassy alloys exhibit useful engineering properties of high mechanical strength. large elastic elongation and high corrosion resistance. In addition, Fe- and Co-based bulk glassy alloys have good soft magnetic properties which cannot be obtained for conventional amorphous and crystalline type magnetic alloys. The Fe- and Ni-based bulk glassy, alloys have already been used in some application fields. These late transition metal base bulk glassy alloys are promising as new metallic engineering materials.

This paper deals with recent progress in stabilized supercooled liquids (SLs) and the resulting bulk glassy, nanoquasicrystalline and nanocrystalline alloys which were mainly conducted by Sendai group in Japan. In this review, the following contents are focused on: bulk metallic glassy alloy systems, empirical rules for the achievement of high glass-forming ability (GFA), local atomic configurations, computational analyses, thermodynamic analysis, mechanical properties, soft magnetic properties, micro-forming ability, application, science and engineering importance and future trend of bulk glassy alloys including SL. As demonstrated in this review, the high stabilization of metallic SLs has already opened up new basic science and engineering application fields and its importance is strongly expected to increase more and more hereafter. © 2003 Elsevier B.V.

This paper deals with recent progress in stabilized supercooled liquid and the resulting bulk glassy alloys and focusing on the following factors; alloy composition, forming ability, formation mechanism, computed glass-forming ability, computed glass formation range, atomic configuration, production techniques, mechanical properties, corrosion resistance, soft magnetic properties, micro-forming ability, applications, significance to science and engineering, and future trends for bulk glassy alloys including supercooled liquid. As demonstrated in this review, the high stability of metallic supercooled liquid has already opened up new fields of investigation in basic science and yielded new engineering applications. There is every reason to expect that their importance will continue to increase.

Ferromagnetic bulk glassy alloys were synthesized in a variety of alloy systems by the copper mold casting process for the last five years after 1995. Their typical alloy systems are classified into five groups, i.e., (1) Fe-(Al, Ga)-(P, C, B) and Fe-Ga-(P, C, B), (2) (Nd, Pr)Fe-(Al, Si), (3) Fe-(Zr, Hf,Nb)-B, (4) Fe-Co-Ln-B, and (5) Fe-(Cr, Mo)-B-C. The Fe-based glassy alloys exhibit a large supercooled liquid region exceeding 50 K before crystallization and the largest value reaches approximately 100 K. The maximum sample thickness of glass formation in the alloy systems belonging to the groups (1) to (5) is about 3 mm, 12 mm, 6 mm, 1 mm and 3 mm, respectively. These bulk glassy alloys exhibit good soft magnetic properties with a maximum saturation magnetization of 1.3 T and low coercive forces below 5 A/m except for hard magnetic properties only for the Nd- or Pr-based alloys. In addition, the application of the consolidation technique using the viscous how phenomenon to the Fe-(AI, Ga)-(P, C, B) alloys caused the formation of fully dense bulk glassy alloys with rather good soft magnetic properties, e.g., 1.2T for saturation magnetization, 10 A/m for coercive force, 9000 for maximum permeability and 0.1 W/kg at 50 Hz for core loss. The combination of good magnetic properties, high glass-forming ability and good workability into a bulk form is promising the future development as a new type of magnetic material.

This article reviews our recent results on the development of ferromagnetic bulk amorphous alloys prepared by casting processes. The multicomponent Fe-(Al,Ga)-(P,C,B,Si) alloys are amorphized in the bulk form with diameters up to 2 mm, and the temperature interval of the supercooled liquid region before crystallization is in the range of 50 to 67 K. These bulk amorphous alloys exhibit good soft magnetic properties, i.e., high B-s of 1.1 to 1.2 T, low H-c of 2 to 6 A/m, and high mu(e) of about 7000 at 1 kHz. The Nd-Fe-Al and Pr-Fe-Al bulk amorphous alloys are also produced in the diameter range of up to 12 mm by the copper mold casting process and exhibit rather good hard magnetic properties, i.e., B-r of about 0.1 T, high H-c of 300 to 400 kA/m, and rather high (JH)(max) of 13 to 20 kJ/m(3). The crystallization causes the disappearance of the hard magnetic properties. Furthermore, the melt-spun Nd-Fe-Al and Pr-Fe-Al alloy ribbons exhibit soft-type magnetic properties. Consequently, the hard magnetic properties are concluded to be obtained only for the bulk amorphous alloys. The bulk Nd-Fe-Al and Pr-Fe-Al amorphous alloys have an extremely high T-x/T-m, of about 0.90 and a small Delta T-m (= T-m - T-x) of less than 100 K and, hence, their large glass-forming ability is due to the steep increase in viscosity in the supercooled liquid state. The high T-x/T-m enables the development of a fully relaxed, clustered amorphous structure including Nd-Nd and Nd-Fe atomic pairs. It is, therefore, presumed that the hard magnetic properties are due to the development of Nd-Nd and Nd-Fe atomic pairs with large random magnetic anisotropy. The Nd- and Pr-based bulk amorphous alloys can be regarded as a new type of clustered amorphous material, and the control of the clustered amorphous structure is expected to enable the appearance of novel functional properties which cannot be obtained for an ordinary amorphous structure.