Resumen

MENDES, Marcio Andreato Batista et al. Selection of compositions with high glass forming ability in the Ni-Nb-B alloy system. Mat. Res. [online]. 2012, vol.15, n.5, pp. 718-722.  Epub 07-Ago-2012. ISSN 1516-1439.  http://dx.doi.org/10.1590/S1516-14392012005000090.

A combination of an extension of the topological instability "λ criterion" and the "average electronegativity" has been recently reported in the literature to predict compositions with high glass-forming ability (GFA). In the present work, both criteria have been applied to select the Ni_61.0Nb_36.0B₃ alloy with a high glass-forming ability. Ingots were prepared by arc-melting and were used to produce ribbons processed by the melt-spinning technique further characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Ni_61.0Nb_36.0B₃ alloy revealed a complete amorphization and supercooled liquid region ΔT_x = 68 K. In addition, wedge-shaped samples were prepared using copper mold casting in order to determine the critical thickness for amorphous formation. Scanning electron microscopy (SEM) revealed that fully amorphous samples could be obtained, reaching up to ~800 µm in thickness.

Palabras llave : metallic glass; rapid solidification processing; ternary alloy systems.