Effect of preparation conditions on the short-range order in Zr-based bulk glass-forming alloys

The short-range order in as-prepared and annealed Zr–Cu–Al–Ni glassy alloys, obtained by quenching from the melt at different cooling rates as well as by solid state reaction via mechanical alloying, was investigated by perturbed angular correlations technique (PAC). All the samples were also characterised by X-ray diffraction and differential scanning calorimetry. For all the as-prepared amorphous samples, the PAC spectra are well described by a Czjzek distribution revealing that the short-range order corresponds to that of a dense random packing of ions. The observed electric field gradient seems to be independent of the preparation method and, when compared with previous measurements, of the Zr content. These trends are discussed in comparison with the similar behaviour observed in binary amorphous alloys. Samples annealed above the glass transition temperature but below the crystallisation step showed two broad distributions of frequencies, which were assigned, to a metastable Ti2Ni-type phase.