Search results for "Amorphous metal"

Explosive crystallization in amorphous CuTi thin films: a molecular dynamics study

2019

Abstract Molecular dynamic simulation was used to study mechanism of self-propagating waves of explosive crystallization (devitrification) in the CuTi metallic glass. Processes in thin rectangular samples composed of one to two million atoms were simulated and compared with experimental data. It was shown that the nucleation of primary crystalline clusters occurs homogeneously due to spontaneous fluctuations of atomic structure; the clusters not

3D magnetic and thermal fields for in the transformer with homogenised amorphous C-core under high frequency

2017

Spark Plasma Sintering of Metallic Glasses

2019

Spark plasma sintering (SPS) of metallic glasses (MG) can be quite different from sintering crystalline metallic alloys. Indeed, MG behave differently with increasing temperature, as they encounter a glass transition and devitrification. Their shaping can thus be compared to what can be performed on thermoplastic polymers. SPS is a promising way to prepare bulk parts from amorphous powders, since it allows very fast heating and cooling rates. It gives an advantage to avoid or limit devitrification of the amorphous phase upon the thermal cycle. However, diffusion mechanisms, which generally control densification, are activated at temperatures that are not compatible with MG structural integr…

On the Structure of Amorphous Metals

2005

Magnetic and structural study of (Fe1−Co )62 Nb8B30 bulk amorphous alloys

2004

Abstract The electric and magnetic properties of rapidly quenched (Fe 1− x Co x ) 62 Nb 8 B 30 bulk metallic glasses were studied with x =0, 0.33 and 0.50. The Curie temperature in the amorphous state was found to be about 245 °C for the Co-free alloy, 290 °C for x =0.33 and 201 °C for x =0.50, while the crystallization temperature is varying within 15° only around 600 °C. The change in T C correlates with the change in Mossbauer parameters. An interesting flattening effect of annealing on the hysteresis loop was observed which increases with the Co content. The resistivity could not be improved above 152 μΩ cm, which limits the high frequency applications of these alloys.

Electrical resistivity of amorphous simple metals at moderately low temperatures

1999

Abstract The dependence of electrical resistivity ρ ( T ) on temperature T in a region of moderate temperatures is considered for amorphous simple metals. It is shown within the Faber–Ziman theory that the ratio [ ρ ( T )− ρ (0)]/ T 2 has a maximum in the temperature region 10 K⩽ T ⩽100 K The theory is illustrated by numerical calculations performed for hard-sphere models of amorphous Mg and Zn.

Solution synthesis of nanoparticular binary transition metal antimonides

2011

The preparation of nanoengineered materials with controlled nanostructures, for example, with an anisotropic phase segregated structure or a regular periodicity rather than with a broad range of interparticle distances, has remained a synthetic challenge for intermetallics. Artificially structured materials, including multilayers, amorphous alloys, quasicrystals, metastable crystalline alloys, or granular metals, are mostly prepared using physical gas phase procedures. We report a novel, powerful solution-mediated approach for the formation of nanoparticular binary antimonides based on presynthesized antimony nanoparticles. The transition metal antimonides M-Sb (M = Co, Ni, Cu(2), Zn) were …

Ni participation in the magnetism of Fe-Ni-Si-B amorphous alloys.

1987

$^{61}\mathrm{Ni}$ M\"ossbauer measurements at 4.2 K have been performed on (${\mathrm{Fe}}_{\mathrm{x}}$${\mathrm{Ni}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${)}_{77}$${\mathrm{Si}}_{1013}$ amorphous alloys with x=0.0, 0.1, and 0.9. Ni atoms in ${\mathrm{Ni}}_{77}$${\mathrm{Si}}_{10}$${\mathrm{B}}_{13}$ bear no magnetic moment, whereas in (${\mathrm{Fe}}_{0.1}$${\mathrm{Ni}}_{0.9}$${)}_{77}$${\mathrm{Si}}_{10}$${\mathrm{B}}_{13}$ and (${\mathrm{Fe}}_{0.9}$${\mathrm{Ni}}_{0.1}$${)}_{77}$${\mathrm{Si}}_{10}$${\mathrm{B}}_{13}$ their moments are, respectively 0.38${\ensuremath{\mu}}_{B}$ and 0.65${\ensuremath{\mu}}_{B}$. Our results, together with the literature data, show that Ni atoms in Fe-…

Electron transport process in simple amorphous metals at moderately low temperatures

2001

Abstract The dependence of electroresistivity ϱ( T ) and electron contribution to thermoconductivity ϰ( T ) of simple amorphous metals is investigated. Calculation of kinetic coefficients is carried out in the nearly free electron approximation (Ziman theory). The form-factor was calculated in the quasiphonon model. In this approximation on the short wavelength part of “dispersion curve” a minimum exists (“roton-like minimum”). It is shown that at moderately low temperatures 10 K ≤ T ≤ 100 K the ratio ϱ(T) − ϱ(0) T 2 has a maximum and the T 2 [ ϰ ( T ) − ϰ (0)] is minimal in this temperature region. Such “anomaly” in the temperature dependence of the kinetic coefficient is due to additional…

Electrical resistivity of simple metal amorphous alloys at moderately low temperatures

2003

Abstract An approach is developed that allows to explain the unusual dependence of the electrical resistivity ρ(T) of amorphous alloys on temperature T. Interactions between the free electrons and the longitudinal acoustic excitations in the small-wavelength region (“the roton region”) are shown to cause such a behaviour of ρ(T) at moderately low temperatures. The features of the electron–phonon interactions in an amorphous alloy as compared to the crystal state case are discussed. The theory is illustrated by numerical calculations of the electrical resistivity ρ(T) for Mg–Zn and Cu–Sn amorphous alloys at the different alloy concentrations in the 0 K temperature range. Qualitative agreemen…