Bulk alloys amorphous

The total density of states (DOS) are obtained by summing of the partial DOS for the atoms in the central part of the structure models in order to reproduce the electronic structure of the bulk alloys as appropriately as possible. The number of the sampled atoms for the calculation of the amorphous alloys is typically 6 for one element. In case of crystals, a few atoms are sampled for calculation. 

The UCu4fiAl8 i system has been obtained in the form of amorphous thin film. From ac resistivity measurements it follows that compared to the results in the crystalline bulk alloys, the onset of magnetic order is suppressed at low Cu concentrations, while the onset of a coherent heavy-fermion state is suppressed at high x. The system reveals a single-ion Kondo behavior down to the lowest temperatures, but significant deviations were detected from the behavior of dipolar Kondo system (Lunkenheimer et al. 1994). 

Fig. 1. Relation between strength and Young s modulus for bulk alloys in amorphous and crystalline states. Reprinted from (Inoue et al., 2004b), with permission from Elsevier.

Fig. 71. Relation between Of and f for bulk icosahedral base Al-Mn-Ce-Co and Al-Cr-Ce-Co alloys produced by extrusion of atomized icosahedral base powders in the temperature range of 573 to 673 K. The data of conventional Al-based alloys and nanogranular crystalline Al-based bulk alloys prepared by extrusion of atomized amorphous powders are also shown for comparison.

R Bellissent, G. Galli, T. Hyeon, S. Magazu, D. Majolino, P. Migliardo, and K. S. Suslick, Structural properties of amorphous bulk Fe, Co and Fe-Co binary alloys, Physica Scripta, T57 79(1995). 

Figure 3. Bulk glass formation range in Pd-Cu-P alloys. Filled symbols are the eompositions where amorphous rods with diameter of 7 mm ean be formed, open eireles represent the formation of erystalline phases.

The Debye temperature of the bulk amorphous alloys was calculated from the relation ... 

Table 3 Room-temperature elastic constants, density, and the Debye temperature p of a number of Pd-Ni-P and Pd-Cu-P bulk amorphous alloys. The elastic moduli are in units of GPa and the density p is in units of g/cm. ...

The calculated Debye temperatures are also listed in Table 3. From this table, it is clear that the elastic properties of the bulk amorphous Pd-Ni-P and Pd-Cu-P alloys change little with changing composition. The elastic moduli of the Pd-Cu-P alloys are slightly lower than those for the Pd-Ni-P alloys. 

The glass stability of the Pd-Ni-P system is wider than that of the Pd-Cu-P system. For most bulk Pd-Ni-P glasses (10-mm diameter), AT> 90 K. The AT values of bulk amorphous Pd-Cu-P alloys are considerably smaller, ranging from 27 to 73 K. 

The elastic constants of bulk amorphous Pd-Ni-P and Pd-Cu-P alloys were determined using a resonant i rasound spectroscopy technique. The Pd-Ni-P glasses are slightly stiffer than the Pd-Cu-P glasses. Within each alloy system, the Young s modulus and the bulk modulus show little change with alloy composition. 

Laser and electron beam processing are effective methods for preparing amorphous surface alloys covering conventional crystalline bulk metals... 

Environmental tests have been combined with conventional electrochemical measurements by Smallen et al. [131] and by Novotny and Staud [132], The first electrochemical tests on CoCr thin-film alloys were published by Wang et al. [133]. Kobayashi et al. [134] reported electrochemical data coupled with surface analysis of anodically oxidized amorphous CoX alloys, with X = Ta, Nb, Ti or Zr. Brusic et al. [125] presented potentiodynamic polarization curves obtained on electroless CoP and sputtered Co, CoNi, CoTi, and CoCr in distilled water. The results indicate that the thin-film alloys behave similarly to the bulk materials [133], The protective film is less than 5 nm thick [127] and rich in a passivating metal oxide, such as chromium oxide [133, 134], Such an oxide forms preferentially if the Cr content in the alloy is, depending on the author, above 10% [130], 14% [131], 16% [127], or 17% [133], It is thought to stabilize the non-passivating cobalt oxides [123], Once covered by stable oxide, the alloy surface shows much higher corrosion potential and lower corrosion rate than Co, i.e. it shows more noble behavior [125]. 

Bellissent R, Galli G, Hyeon T, Magazu S, Majolino D, Migliardo P, Suslick KS (1995) Structural properties of amorphous bulk Fe, Co, and Fe-Co binary alloys. Phys Scripta 57 79-83, References and further reading may be available for this article. To view references and further read purchase this article... 

The equilibrium, room temperature structure of pure cobalt is hep. The fee structure is stable at high temperatures (422 °C to 1495 °C) and has been retained at room temperature by rapid solidification techniques [101], X-ray diffraction analysis was used to probe the microstructure of bulk Co-Al alloy deposits containing up to 25 a/o Al and prepared from solutions of Co(II) in the 60.0 m/o AlCfi-EtMelmCl melt. Pure Co deposits had the hep structure no fee Co was observed in any of the deposits. The addition of aluminum to the deposit caused a decrease in the deposit grain size and an increase in the hep lattice volume. A further increase in the aluminum content resulted in amorphization of the deposit [44], Because the equilibrium... 

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