Glassy metal alloys

A molten metal alloy would normally be expected to crystallize into one or several phases. To form an amorphous, ie, glassy metal alloy from the Hquid state means that the crystallization step must be avoided during solidification. This can be understood by considering a time—temperature—transformation (TTT) diagram (Eig. 2). Nucleating phases require an iacubation time to assemble atoms through a statistical process iato the correct crystal stmcture... 

Pd trimethylphosphine carbonyl clusters, CO FTIR spectra, 39 174-175 PdjWjCpjfCOl fPPh,), 38 350-351 Pdo.2,Zro glassy metal alloy, 38 71 Pebbly surface model, 39 114 Peclet number, 27 80, 81... 

Melt spinning Splat quenching Water quenching Glassy metallic alloy ribbon Fine-grained polycrystalUne bulk solids... 

In work by Kreysa and Hakansson (795), the glassy metal alloy Fe6oCo2oSiioBio provides lower H2 overvoltage behavior than either Pt or Ni and is also effective for anodic O2 evolution (in which case its surface becomes covered by an oxide film). Also, Co5oNi2sSi,5Bio is a favorable O2 evolution... 

Table 4.1. Glassy metal alloys used in catalytic applications...

Figure 4.19B shows the progress of crystallization during the in situ activation as determined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The bulk structural changes of the glassy metal alloy during the in situ activation are reflected by the XRD traces shown in Fig. 4.20, which depicts the results of two analyses from samples taken at typical points in the activation curve (Fig. 19A) namely, in the low activity region (top trace in Fig. 4.20) and in the final stage of activation (bottom trace in Fig. 4.20). Comparison of the two wide scans in Fig. 4.20 shows the significant increase in...

Polk, D. E. (1972) The structure of glassy metallic alloys, Acta MetalL, 20, 485-491. 

Small amounts of ternary metal phosphides are important for special purposes. Thus, Florenskyite, FeTiP [22], is utilised for precipitation hardening in interstitial-free ferrite steels [23]. Other ternary phosphides with similar (FcjP type) crystal structures (Chapter 8.1), for example, NiCrP, MoNiP and FeNiP can strongly inflnence the microstructure and mechanical properties of glassy metal alloys. 

Glassy metal alloys, in thin film or bulk form, are not in a state of... 

None of what we have discussed so far is specific to polymers. One can almost conclude that every liquid forms a glass on cooling, provided it is cooled fast enough. A cooling rate of 10 K/s vitrifies liquid argon in a computer simulation, and lO K/s produces glassy metallic alloys, whereas polymers can be cooled as slowly as 10 K/s and still do not crystallize. The frozen-in amorphous structure can be kept at (meta-)stable equilibrium even close to Tg and may be as close to the thermodynamic equilibrium... 

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