Passivity of Extremely Corrosion Resistive Iron Alloys

This paper reviews studies on corrosion resistance of chromium bearing amorphous iron alloys and high purity-high chromium ferritic steels containing molybdenum. High corrosion resistance of these alloys have been interpreted in terms of the compositions and functions of the passive films formed on these alloys

ESCA Study of the Passive Film on an Extremely Corrosion-Resistant Amorphous Iron Alloy

X-ray photoelectron spectroscopy was applied to study the composition of the passive film formed on an extremely corrosion resistant amorphous Fe-10at.%Cr-13at.%P-7at.%C alloy in 1 N HCl. The passive film consists mainly of hydrated chromium oxyhydroxide which is a common major constituent of passive films on crystalline stainless steels. The extremely high corrosion resistance of the amorphous alloy can only in part be attributed to the formation of a protective hydrated chromium oxyhydroxide film

Invar-Type New Ferromagnetic Amorphous Fe-B Alloys(Physics)

Measurements of magnetization, electrical resistivity, thermal expansion and differential thermal change were made on amorphous Fe_B_x (9≦X≦21) alloys prepared by rapid quenching from the liquid state. With decreasing boron content in the alloys, the Curie temperature falls remarkably, while the magnetic moment increases sluggishly. The thermal expansion curves exhibit the invar characteristics below the Curie temperature due to a large positive spontaneous volume magnetostriction, and the reduced magnetization curves decrease much more rapidly with increasing temperature than those of other ferromagnetic amorphous alloys

Electrical Properties of Amorphous Cu-Zr Alloy

The electrical resistivity of amorphous Cu_-Zr_ alloy and the temperature coefficient of the resistivity are estimated to be 195μΩ・cm and -1.23×10^μΩ・cm/°K at 273°K, respectively. The Hall coefficient and the thermoelectric power are equal to +7.4×10^ m^3/AS and +0.39μV/°K, respectively. These electrical properties are similar to those for some liquid transition metals

High Permeability and Low Core Losses of Nanocrystalline Fe-Nb-Zr-B-Cu Alloys

Nanocrystalline Fe-M-B (M=Zr or Nb) alloys prepared by crystallization of rapidly quenched amorphous ribbons are known as a new class of soft magnets with high saturation magnetization. In order to improve their soft magnetic properties further, the reduction of their magnetostriction to zero was attempted by a combined addition of Zr and Nb, because the signs of the magnetostriction of the Fe-Zr-B and the Fe-Nb-B at each optimum condition are known to be opposite. Further, the B concentration was reinvestigated under a Cu addition and the combined addition of Zr and Nb in order to further refine the grain size and to improve the intergranular exchange coupling. As a result, the small average grain size of 8nm and nearly zero magnetostriction has been simultaneously obtained in the Fe_Nb_Zr_B_8Cu_1 alloy. This alloy simultaneously exhibits the high permeability of 100, 000 (at 1kHz) and the high saturation flux density of 1.53T, satisfying the both properties in the highest level among the rapidly quenched ribbons ever reported. The core losses of the nanocrystalline Fe_Nb_Zr_B_8Cu_1 alloy are lower than those of the amorphous Fe-Si-B alloys over a wide frequency and Bm (maximum induction) range. Further, the core losses are almost unchanged under the stresses such as epoxy resin molding. These new nanocrystalline materials are suitable for use in advanced electronic devices such as inductors or transformers

Scaling in the correlation energies of two-dimensional artificial atoms

We find an unexpected scaling in the correlation energy of artificial atoms, i.e., harmonically confined two-dimensional quantum dots. The scaling relation is found through extensive numerical examinations including Hartree-Fock, variational quantum Monte Carlo, density-functional, and full configuration-interaction calculations. We show that the correlation energy, i.e., the true ground-state total energy subtracted by the Hartree-Fock total energy, follows a simple function of the Coulomb energy, confimenent strength and, the number of electrons. We find an analytic expression for this function, as well as for the correlation energy per particle and for the ratio between the correlation and total energies. Our tests for independent diffusion Monte Carlo and coupled-cluster results for quantum dots -- including open-shell data -- confirm the generality of the obtained scaling. As the scaling is also well applicable to $\gtrsim$ 100 electrons, our results give interesting prospects for the development of correlation functionals within density-functional theory.Comment: Accepted to Journal of Physics: Condensed Matte