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Study on Cu₄₈Zr₄₃Al₉ and Cu₅₄Zr₄₀Al₆ Amorphous Matrix Alloys by Mechanical Spectroscopy

2015; Trans Tech Publications; Volume: 365; Linguagem: Inglês

10.4028/www.scientific.net/ddf.365.317

1662-9515

Odila Florêncio, Paulo Wilmar Barbosa Marques, Paulo Sergio Silva, Javier Andrés Muñoz Chaves, Luis César Rodríguez Aliaga, Walter José Botta Filho,

Phase-change materials and chalcogenides

Anelastic properties of Bulk Metallic Glasses (BMG) were studied by mechanical spectroscopy using a flexural vibration apparatus. BMG’s samples, with nominal composition Cu 48 Zr 43 Al 9 and Cu 54 Zr 40 Al 6 , were produced by skull push-pull casting technique in rectangular cavity cooper mold. In both samples, the differential scanning calorimeter patterns have evidenced the presence of amorphous structure, although the X-ray diffraction for Cu 48 Zr 43 Al 9 composition has shown a heterogeneous microstructure embedded in the amorphous matrix. Anelastic relaxation spectra were obtained using an acoustic elastometer system with vibration frequency in the kilohertz bandwidth, a heating rate of 1 K/min, vacuum greater than 10 -5 mBar in the temperature range of 300 K to 620 K. In the flexural apparatus, an acoustic elastometer system, the internal friction (energy loss) and the elastic modulus were obtained by free decay of vibrations and by the squared of the oscilation frequency, respectively. Internal friction spectra were not reproducible among the measurements, which may imply atomic rearrangement in the samples due to consecutive heating. Normalized elastic modulus data showed distinct behavior from the first to the other measurements evidencing irreversible microstructural alterations in the samples possibly associated with mechanical relaxation due to the motion of atoms or clusters in the glassy state.