Bulk glassy alloys

Kawashima, A., Zeng, Y., Fukuhara, M., Kurishita, H., Nishiyama, N., Miki, H., and Inoue, A. (2008) Mechanical properties of a Ni6oPd2oPi B3 bulk glassy alloy at cryogenic temperatures, Mater. Sci. Eng., A498, 475-481. 

Zirconium-based alloys were among the first non-noble metal-based alloys found to solidify in the amorphous state upon cooling from the melt at corrparatively low rates R, such as 10 Ks [1.69,70]. The term bulk glassy alloys refers to the fact that this solidification behavior permits us to obtain bulky parts with an amorphous structure by conventional casting procedures, e.g., in rod form, up to 30 mm. Data are given in [1.71,72]. 

There are no tabulated data of the properties of Zr-based bulk glassy alloys available yet. A typical set of data is given in Table 3.1-39 [1.75]. 

Inoue A, Takeuchi A, Recent progress in bulk glassy alloys . Materials Transactions JIM, 2002 43 1892-1906. 

Park ES, Kim DH, Eormation of Mg-Cu-Ni-Ag-Zn-Y-Gd bulk glassy alloy by casting into cone-shaped copper mold in air atmosphere . Journal of Materials Research, 2005 20 1465-1469. 

Yuan G, Qin C, Inoue A, Mg-based bulk glassy alloys with high strength above 900 MPa and plastic strain . Journal of Materials Research, 2005 20 394-401. 

Figure 4. DSC traces for three bulk glassy Pd-Ni-P alloys at the heating rate of 20 K/min.

The bulk structural changes of the glassy alloy were followed by XRD. Figure 2 depicts the XRD patterns of the precursor alloy before and after oxidation, and after use of the samples in long term CO oxidation tests. 

Another group of amorphous semiconductors are the A compounds and alloys. a-SiO, which is a much investigated material with large technical uses, a-SnTe, a-PbTe and the whole series of a-Ge Te. and a-Ge Se. alloys can be obtained by vacuum evaporation or sputtering. Bulk glassy Ge Tej j and Gej Sei j alloys can be obtained by splat-cooling the melt or even slower quenching if relatively small quantities of P, As, S, Si, or I are added to the melt. This is most easily achieved around the compositions close to an eutecticum (Hilton, Jones, and Brau, 1966 Feltz et al, 1971), e.g. for X — 0.15 in the Ge-Te system. 

Fig. 49. Fatigue life curves for some lilamenis of glassy metals. Full curves indicate ribbons and broken curves indicate wires. For further details and references see Table 7. The curves for the wires and the FeCr alloy have been measured in the bending mode with imposed surface strain. In order to represent the.se on the same stress scale this strain has been multiplied by their Young modulus. The bulk amorphous alloy has also been measured in the bending mode but with imposed bending stress.

It is impossible to date to derive from first principles which alloy compositions are prone to easy glass formation. It has been found empirically that multi-component alloys with components of significantly different ionic radii are suitable candidates in principle. Examples of Zr-based systems that show bulk glassy solidification behavior are listed in Table 3.1-38. 

Table 3.1-38 Zr-based alloy systems exhibiting bulk glassy behavior...

SEM image of a corroded surface of a bulk glassy MgesCuy.sNiy.sAgsZnsGdsYs alloy sample after anodic polarization in a 0.0001 M NaCI solution with pH=9 pitting and filiform corrosion. 

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