Papers by Keyword: Glass-Forming Ability

Abstract: New techniques for the analysis of complex images were advanced by the example of asurface microrelief of the Fe70Cr15B15 alloys, obtained by the melt-spinning at different linearvelocity of a quenching roller. Proposed techniques are based on the fast Fourier transform of theimage using digital signal processors. The degree of morphological ordering/disordering of ribbonswas determined due to the parameterization of mode spectra by entropy functionals. The best glassforming ability for alloys of the studied composition was obtained at 30 m/s.

Abstract: The thermal stability, glass-forming ability, soft-magnetic properties and mechanical properties of Co₄₆Fe_19+xB_22.5Si_5.5Nb_7–x (x=0–2) bulk metallic glasses were investigated. The 5.5 at% Nb addition was found to be effective in approaching alloy to a eutectic point, resulting in an increase in glass-forming ability. By copper mold casting, bulk metallic glass rods with diameters up to 5 mm were produced. Except for high glass-forming ability, the bulk metallic glasses also exhibit good soft-magnetic properties, i.e., low coercive force of 1.34–2.14 A/m, high effective permeability at 1 kHz of 2.26–3.06×10⁴, and high fractures strength (σ_f) of 4010–4460 MPa. This Co-based bulk metallic glass system with high strengths and excellent soft-magnetic properties is promising for future applications as a new functional material.

Abstract: We investigated the effects of addition elements (Sn, Al, Si, Ag, Fe, Cr) with a small amount on the glass-forming ability, thermal stability and mechanical properties of the Ti-Zr-Cu-Pd glassy alloy system. The results revealed that minor Sn addition improved the glass-forming ability, thermal stability and plasticity, Si addition enlarged the supercooled liquid region, and Fe addition improved the plasticity, while minor additions of Si, Ag, Fe, and Cr lowered the glass-forming ability, and Al and Cr additions were harmful to the plasticity of the Ti-Zr-Cu-Pd glassy alloy system.

Abstract: The glass forming ability and magnetic properties were investigated for adding neodymium to the Fe_71-xNb₄B₂₅Nd_x (x=0, 3, 5, 7,10) alloys prepared by copper suction casting. It was found that proper neodymium (x=5~10 at.%) could improve glass forming ability of Fe-Nb-B alloys effectively. Bulk amorphous Fe₆₆Nd₅B₂₅Nb₄ and Fe₆₄Nd₇B₂₅Nb₄ samples were obtained and presented high thermal stability and good soft magnetic properties. The value of activation energy of the first crystallization peak for the bulk amorphous alloy Fe₆₄Nd₇B₂₅Nb₄ is 683 kJ/mol.

Abstract: The SiO₂-B₂O₃-Al₂O₃-Na₂O-PbO system glass powders were prepared by the high temperature water quenching and ball milling. The effects of CaO, Li₂O and ZnO with content of 1~5 wt.% on the glass-forming ability, softening temperature and crystallization behavior of the SiO₂-B₂O₃-Al₂O₃-Na₂O-PbO system glass powders were investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results showed that the glass crystallization tendency became obvious with the increase of CaO and Li₂O content, the melting temperature of the glass decreased with the addition of 1% Li₂O, while the effect of CaO with content lower than 2% on the formation of glass was not obvious. The addition of ZnO favored the formation of glass, however, the softening temperature of the glass increased with the increase of ZnO content. The softening temperature of the SiO₂-B₂O₃-Al₂O₃-Na₂O-PbO system glass powder decreased by 42.5°C with the addition of 2%CaO-1%Li₂O-1%ZnO.

Abstract: Glass-forming ability in the P₂O₅-ZnO-SrO-K₂O system was investigated using differential thermal analyzer (DTA). The results showed that adding appropriate amount of K₂O could improve the glass-forming ability of phosphate glasses. Meanwhile, the spectroscopic properties of Tm/Tb/Mn co-doped phosphate glasses were studied by photoluminescence (PL) measurements and CIE color coordinate. Blue, green, and reddish orange emission bands were observed in the PL spectra of the phosphate glasses. The combination of these emission bands gave white light by ultraviolet light excitation (360nm). As the Tb₄O₇ was increased,a gradual shift from white emission to yellow emission was observed in the PL spectra of the glasses. These three ions-doped phosphate glasses are potential candidates for white light-emitting diodes.

Abstract: A new bulk amorphous alloy, Y₃₆Nd₂₀Al₂₄Co₂₀, with a diameter of 5 mm was successfully fabricated by the method of equiatomic substitution for the Y element in Y₅₆Al₂₄Co₂₀ amorphous alloy. The values of the supercooled liquid region ∆T_x(=T_x-T_g ), the reduced glass transition temperature T_rg (=T_g/T_l) and the parameter γ (=T_x/(T_g+T_l)) for Y₃₆Nd₂₀Al₂₄Co₂₀ bulk amorphous alloy are 60K, 0.605 and 0.415, respectively. The critical cooling rate of the Y₃₆Nd₂₀Al₂₄Co₂₀ bulk amorphous alloy was determined to be 40 K/s, providing an indication that this alloy has a high glass-forming ability.

Abstract: Glass forming ability and crystallization kinetics of Al-Mg-Ni-La alloys have been investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The maximum thickness achievable in glasses of Al₇₆Mg₁₁Ni₈La₅ and Al₆₉Mg₁₈Ni₈La₅ ribbons were 200 and 120 μm, respectively. The crystallization temperature and peak temperature indicated by DSC measurements displayed dependence on the heating rate during continuous heating, and were coincident with Lanoka’s relationship. The activation energies for the crystallization reaction E_x were obtained from the Kissinger’s equation. The results show the Mg addition is beneficial to the thermal stability of the amorphous phase.

Abstract: The effect of B₂O₃ fluxing on the glass-forming ability (GFA), the structure and the soft magnetic properties of Fe (-Co)-B-Si-Nb bulk metallic glasses (BMGs) has been investigated. The large Fe-Co-B-Si-Nb BMG specimens with diameters up to 7.7 mm, which is approximately 1.5 times as large as that of the maximum diameter of the copper mold cast one (= 5 mm), were prepared by the fluxing and water quenching. Thus the GFA of the Fe-Co-B-Si-Nb BMG are improved by the fluxing. It was confirmed that the soft magnetic properties of the Fe-Co-B-Si-Nb BMG are also improved by the fluxing. On the other hand, it was found for the Co-free Fe-B-Si-Nb BMG that the B₂O₃ fluxing promotes the precipitation of the α-Fe (-Si) and Fe₂B phases in the central region of the specimens; i.e., the GFA of the Fe-B-Si-Nb BMG is decreased by the fluxing. The Fe-B-Si-Nb BMG specimens show a flat hysteresis loop, indicating a good linear relationship between the magnetic induction and the applied magnetic field. These results of the Fe-B-Si-Nb BMG show that it is possible to develop a new soft magnetic material that exhibits constant permeability, which is necessary for producing inductors and choke coils.

Abstract: Bulk Fe₇₃Nb₃Al₂Ge₂P₉C₆B₄Si₁ metallic glass with the diameter of 2 mm was prepared by copper mold casting. The Fe-based metallic glass exhibits good magnetic properties with high saturation magnetization and low saturated magnetostriction. The saturation magnetization and coercive force remains almost unchanged with annealing temperature below the crystallization temperature. The crystallization leads to the decrease in the softness of magnetic properties. The Fe-based glass exhibits a good correspondence between large glass-forming ability and good soft magnetic properties.