Appearance Of Supercooled Liquid Region Research Articles

The relationship between the stability of glass-forming Fe-based liquid alloys and the metalloid-centered clusters

This article considers the roles of metalloids in two typical Fe-based glass former alloys (Fe78Si9B13 and Fe80P11C9) in liquid state by using ab initio molecular dynamics simulations. It presents that Fe78Si9B13 alloy is mainly composed of B-centered prism-like clusters and bcc-like Fe-Si solid solution, while P-centered antiprism-like and C-centered prism-like clusters dominate in Fe80P11C9 alloy. The different liquid stabilities of the two alloys can be attributed to the different local environments around P and Si atoms and the different avoidance of metalloid atoms. The appearance of supercooled liquid region for metallic glasses has gained a better understanding based on these models.

Structure and soft magnetic properties of bulk Fe-Al-Ga-P-C-B-Si glassy alloys prepared by consolidating amorphous powders

Structure and soft magnetic properties of the bulk Fe 70Al 5Ga 2P 9.65C 5.75B 4.6Si 3 glassy alloy prepared by pulse current sintering with uniaxial pressure were investigated. The sample consolidated in the temperature range of the supercooled liquid region consists only of amorphous phase and has a very high relative density of 99%. The flux density under applied field of 800 A/m ( B 800), maximum permeability ( μ max) and coercive force ( H c) for the sample sintered at 703 K in as-made state are 1.08 T, 7600 and 12.0 A/m, respectively. B 800 and μ max are improved to 1.17 T and 8000 by annealing at 723 K for 3.6 ks. The soft magnetic properties of the bulk Fe-based glassy alloy are superior to those of the bulk Fe-Si-B alloy consolidated amorphous powders. It is considered that the high relative density and good soft magnetic properties for the bulk Fe-based glassy alloy depend upon its high structural homogeneity originated from its high deformability, that is based on the viscous flow arisen from the appearance of supercooled liquid region.

Local atomic structure of [formula omitted] amorphous alloys with supercooled liquid region

The local ordering structures of Fe 70Co 10B 20 and Fe 67 Co 10 Ln 3 B 20 ( Ln= Sm, Tb or Dy ) alloys have been studied by X-ray diffraction. The analyses of interference functions and radial distribution functions revealed that the local atomic ordering becomes weaker and the coordination number of transition metals around Fe decreases while that of transition metals around B remains almost unchanged by the addition of Ln element to Fe–Co–B alloy. These results indicate that the amorphous phase consists of (Fe,Co)–B-based rigid local structure units and the Ln atom is inserted between them. The unique structure may cause the appearance of supercooled liquid region with the difficulty of re-arrangement of atoms during annealing.

パルス通電焼結法により作製したFe基金属ガラスバルク材の構造と軟磁気特性

Structure and soft magnetic properties for the bulk Fe70Al5Ga2P9.65C5.75B4.6Si3 glassy alloy prepared by pulse current sintering with uniaxial pressure were investigated. The sample consolidated in the temperature range of the supercooled liquid region consisted only of amorphous phase and had a very high relative density of 99%. The flux density at the applied magnetic field of 800 A/m, maximum permeability, coercive force and relative permeability at 1 kHz for the sample sintered at 703 K in as-made state are 1.1 T, 7600, 12 A/m and 1700 respectively. The soft magnetic properties of the sintered bulk Fe-based glassy alloy were much superior to the other magnetic materials of consolidated amorphous powders. It is concluded that the high relative density and good soft magnetic properties for the bulk Fe-based glassy alloy should depend upon its high structural homogeneity originated from its high deformability, that is based on the viscous flow arisen from the appearance of supercooled liquid region.

Stability and transformation to crystalline phases of amorphous ZrAlCu alloys with significant supercooled liquid region

Crystallization from the supercooled liquid region was examined for an amorphous Zr 65Al 7.5Cu 27.5 alloy with a significant supercooled liquid region before crystallization, with the aim of investigating the reason for the appearance of the wide supercooled liquid region. The crystallization takes place through the precipitation of a b.c.t. Zr 2(Cu, Al) single phase which grows with a dendritic mode. The Avrami exponent ( n value) and the activation energies for the nucleation and crystallization are 3.7, 260 and 230 kJ mol −1 respectively. Based on existing structural data as well as the present results, it is presumed that the appearance of the supercooled liquid region is due to the difficulty of growth resulting from the necessity of long-range redistribution of Al at the solid-liquid interface and to the difficulty of precipitation of Zr 2(Cu, Al) caused by the large solid-liquid interfacial energy resulting from the highly dense random packed structure consisting of elements with significantly different atomic sizes and attractive bonding nature.