Fe40Ni40B20 Metallic Glass Research Articles

Studying nearest neighbor correlations by atom probe tomography (APT) in metallic glasses as exemplified for Fe40Ni40B20 glassy ribbons

A next nearest neighbor evaluation procedure of atom probe tomography data provides distributions of the distances between atoms. The width of these distributions for metallic glasses studied so far is a few Angstrom reflecting the spatial resolution of the analytical technique. However, fitting Gaussian distributions to the distribution of atomic distances yields average distances with statistical uncertainties of 2 to 3 hundredth of an Angstrom. Fe40Ni40B20 metallic glass ribbons are characterized this way in the as quenched state and for a state heat treated at 350°C for 1h revealing a change in the structure on the sub-nanometer scale. By applying the statistical tool of the χ2 test a slight deviation from a random distribution of B-atoms in the as quenched sample is perceived, whereas a pronounced elemental inhomogeneity of boron is detected for the annealed state. In addition, the distance distribution of the first fifteen atomic neighbors is determined by using this algorithm for both annealed and as quenched states. The next neighbor evaluation algorithm evinces a steric periodicity of the atoms when the next neighbor distances are normalized by the first next neighbor distance. A comparison of the nearest neighbor atomic distribution for as quenched and annealed state shows accumulation of Ni and B. Moreover, it also reveals the tendency of Fe and B to move slightly away from each other, an incipient step to Ni rich boride formation.

Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mossbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5×1013 and 7.5×1013 ions/cm2. The relative intensity ratios D 23 of the second and third lines of the Mossbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.

Neutron depolarization study of internal stresses in amorphous Fe40Ni40B20

The magnetic domain structure of amorphous ferromagnets with nonzero magnetostriction is mainly determined by the internal stress state because of the magneto-elastic coupling. The stress and field dependence of the domain structure contains important information on the internal stresses in the material. The three-dimensional neutron depolarization technique has been used to study the stress- and field-dependence of the bulk domain structures in both as-quenched and annealed ribbons of the metallic glass Fe40Ni40B20. A three-layer domain structure model corresponding to compressive and tensile internal stresses is presented to explain the measured data. The influence of surface roughness on the interpretation of neutron depolarization measurements in amorphous ribbons is discussed. Finally, the internal stress relaxation due to the annealing is explained in terms of the viscous behaviour of the glass.

X-ray photoemission study of Fe40Ni40B20 metallic glass

X-ray photoelectron spectroscopic (XPS) study of the valence band and the core levels of amorphous Fe40Ni40B20 are presented. The oxides which formed at the surface of as-received sample are due to oxidation of iron and boron. For etched samples, the presence of oxide is not discernible, and the chemical environment is predominantly iron-boron-like, while nickel remains unassociated. The valence band has a high density of states at Fermi levels of amorphous Fe40Ni40B20 are presented. The oxides which formed at the surface of B2s and Fe3d states, and metalloids-states respectively.

Mechnical properties of thermoplastic film/metallic glass composites with improved interfacial strength

AbstractThe mechanical properties of the uniaxial and continuous composite with high strain to fracture PP matrix reinforced with the Fe40Ni40B20 (at%) and Metglas 2605SC metallic glass ribbons have been determined and compared with the rule of mixtures. The reinforcing ribbons were coated with PVA (polyvinlyl alcohol) to improve interfacial bonding. The experimental fracture strength results for both types of reinforcement deviate from the values predicted. The strength of composite at the fracture strain of ribbon determined experimentally obeys a modified rule of mixture (isostrain condition) for both types of reinforcement over the entire volume fraction range of reinforcement (up to 16%). The experimental composite eleastic modulus results for composite reinforced with relatively narrow Fe40Ni40B20 ribbons are found to be generally near the values predicted by the rule of mixtures, but for the Metglas 2605SC wide the modified rule of mixtures, which takes into account the thermally induced tensile stresses at the interface resulting from the mismatch of the coefficients of thermal expansion.

Differential scanning calorimetry investigation of as-quenched Fe40Ni40B20 metallic glass prepared under different cooling conditions

Differential scanning calorimetry investigation of as-quenched Fe40Ni40B20 metallic glass prepared under different cooling conditions

Propagation of Fatigue Crack in Amorphous Fe<sub>40</sub>Ni<sub>40</sub>B<sub>20</sub> at High-Fequency Loading

This work studies the fatigue crack growth in Fe40Ni40B20 metallic glass using the stressing by longitudinal ultrasonic waves of frequency 20.2 kHz. A relation between the rate of fatigue crack propagation and stress intensity factor is derived. An extremely low threshold value of the stress intensity factor, below which a fatigue crack cannot propagate, was found. Fractographic analysis of the fatigue fracture surfaces by scanning electron microscopy confirmed that no so far known mechanism of fatigue failure was present. No slip bands were observed near fatigue fracture surfaces.

Microstructural and kinetic aspects of devitrification of Fe40Ni40B20 metallic glass

The crystallization characteristics of Vitrovac 0040 commercial glass with a composition of Fe40Ni40B20 have been investigated in detail using differential scanning calorimetry, X-ray diffraction, optical and electron microscopy techniques. The results confirm the simultaneous occurrence of four kinds of crystalline precipitates with differing growth behaviour. The overall transformation kinetics of the eutectic product which had the highest growth rate has been documented. The result yielded a low value of 2.08 for the Avrami exponent, which has been attributed to its athermal nucleation and anisotropic growth behaviour. The diffusivity obtained from interlamellar spacings has been found to agree well with the previous values obtained by direct measurement using secondary ion mass spectroscopy for boron diffusion.

Creep recovery spectra in Fe40Ni40B20 metallic glass

Creep recovery spectra in Fe40Ni40B20 metallic glass

The generalised vibrational density of states of the metallic glass Fe40Ni40B20 determined by neutron inelastic scattering

The generalised vibrational density of states G( omega ) has been derived from inelastic neutron scattering measurements for the ternary transition metal-metalloid metallic glass Fe40Ni40B20. Two main energy bands are observed centred around 24 and 63 meV and separated by a shallow pseudo-gap near 50 MeV. The former band is mainly due to transition metal-transition metal interaction, the latter is associated to localised optical modes involving transition metal-boron bonds. Rather small differences, if any at all, have been observed for samples prepared by the metal spinning technique at different velocities of the rotating wheel. The neutron weighted G( omega ) have been used to calculate thermodynamic quantities like the temperature dependence of the specific heat and of the Debye temperature.

Crystallization of the amorphous alloy Fe40Ni40B20: a ferromagnetic resonance study

The ferromagnetic resonance (FMR) technique was used to study the crystallization of the metallic glass Fe40Ni40B20 (Vitrovac 0040). The line intensity of the amorphous phase was measured for several isothermal annealing times in the temperature range 360 to 375° C. The transformed fraction, as derived from FMR data, satisfies the Johnson-Mehl-Avrami equation with the exponentn between 1.49 and 1.70. The activation energy for crystallization is estimated from the times to 25% to 75% transformation to be 364 kJ mol−1.

The reversible enthalpy change of the metallic glass Fe40Ni40B20 ? Experiments and simulation in the activation energy spectrum model

The activation energy spectrum model can be used quite successfully to explain various aspects of the kinetics of structural relaxation in metallic glasses. In order to describe the often observed reversible component in a more quantitative way in the framework of this model an expression for the temperature dependence of the reversible part of the activation energy spectrum is derived. Using this expression three experiments concerning the reversible enthalpy change during structural relaxation are simulated and the results are compared with the actual experimental traces.

Structural Relaxation in Fe40Ni40B20 Metallic Glass: Evolution of Resistivity at Temperature in Electrically Self-Heated Specimens*

Article Structural Relaxation in Fe40Ni40B20 Metallic Glass: Evolution of Resistivity at Temperature in Electrically Self-Heated Specimens* was published on January 1, 1988 in the journal Zeitschrift für Physikalische Chemie (volume 157, issue 1).

Low-temperature fracture toughness of some iron, nickel-based metallic glass ribbons

The critical stress intensity factor of Fe40Ni40B20, Ni80Si10B10 and Ni80Si5B15 metallic glass ribbons was measured at temperatures 4.2 to 300 K. The low-temperature embrittlement for Ni-Si-13 glasses was not investigated. The low-temperature embrittlement of Fe40Ni40B20 glass depends on the structural relaxation and is connected with a change from vein pattern fracture surface morphology through chevron morphology up to cleavage.

Fracture toughness of some metallic glasses

The critical stress intensity factor of Fe40Ni40B20, Fe30Cr10Ni40B20, Ni80Si10B10 and Ni80Si5B15 metallic glass ribbons was measured. Stressing by ultrasound, a new method for preparation a sharp crack in a metallic glass, was used. Only shear rupture failures was investigated for all alloys.

Effect of H+ ion irradiation on surface morphology of Fe40Ni40B20 metallic glass

The effect of irradiation by H+ ions on surface modifications of metallic glass Fe40Ni40B20, in the as-quenched, structurally related and crystallized state, has been studied. Swollen regions develop on the surface of the as-quenched and structurally relaxed specimens, whereas blisters form on the surface of the crystallized specimen, under identical conditions of irradiation. The results are explained in terms of the distribution of hydrogen in the amorphous and crystallized conditions.

Crystallization of the Metallic Glass Fe40Ni40B20 during Isochronal Annealing in Argon and Hydrogen

The ribbons of metallic glass Fe40Ni40B20 are annealed isochronally in argon and hydrogen in the range of temperatures 360 to 800 °C. The X-ray diffraction shows quantitative differences in the temperature dependences of the volume contents of the crystalline phases: orthorhombic boride (FeNi)3B and austenit γ-FeNi, indicating the difference in kinetics of crystallization in argon and hydrogen. A qualitative explanation is attempted. Proben des metallischen Glases Fe40Ni40B20 werden bei einer Temperatur von 360 bis 800 °C isochron getempert. Rontgenstrahlbeugungsuntersuchungen zeigen quantitative Unterschiede in den Temperaturabhangigkeiten der Volumeninhalte der kristallinen Phasen: rombisches Borid (FeNi)3B und Austenit γ-FeNi, die auf den Unterschied in der Kinetik der Kristallization in Argon und Wasserstoff hinweisen. Eine qualitative Erklarung wird versucht.

Surface oxidation of Fe40Ni40B20 metallic glass

Surface oxidation of Fe40Ni40B20 metallic glass

Structure analysis of the metallic glass Fe40Ni40B20 using the tangent lattice model

The electrical resistivity is adopted as a structure sensitive property to trace atomic rearrangments before and after crystallization of the metallic glasses. Hence, using Ziman-Evan's theory the electrical resistivity for the amorphous phase of metglass is calculated, taking into consideration the radial distribution function for the tangent lattice model. From the calculations a model based on atomic tilting can be adopted and 8 tangent lattice form can be applied to the amorphous state of metglasses such as Fe40Ni40B20. Der elektrische Widerstand wird als strukturempfindliche Eigenschaft benutzt, um atomare Umordnungen vor und nach der Kristallsation von metallischen Glasern zu verfolgen. Deshalb wird mti der Theorie von Ziman-Evans der elektrische Widerstand fur die amorphe Phase von Metglas berechnet, wobei die radiale Verteilungsfunktion fur das Tangentengittermodell berucksichtigt wird. Aus den Berechnungen kann ein Modell auf der Grundlage der atomaren Kippung entnommen werden. und es last sich eine Tangentengitterform auf den amorphen Zustand von Metglasern wie Fe40Ni40B20 anwenden.

Investigation of the metallic glass Fe40Ni40B20 with the use of positron annihilation methods

en