Enhanced thermal stability of Zr56Co28Al16 bulk metallic glass with addition of Ag and Cu elements

The non-isothermal crystallization kinetics of Zr56Co28Al16, Zr56Co24Ag4Al16 and Zr56Co22Cu6Al16 BMGs were studied by differential scanning calorimetry at the continuous heating rates of 10, 20, 30 and 40 K/min. The crystallization kinetics parameters, including the effective and local activation energies corresponding to the characteristic temperatures, sensitivity of the characteristic temperatures to the heating rate were investigated. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate the glassy alloys structure. The activation energies of characteristic temperatures were obtained by Kissinger and Ozawa methods. Also, the heating rate sensitivity of characteristic temperatures was determined by Lasoca method. The Ag-bearing Zr-based BMG presented higher activation energies with values of Eg=402, EX1= 336 and EX2= 395 kJ/mol and lower heating rate sensitivity in regard to characteristic temperatures, indicating a higher stabilization of the supercooled liquid, which can be correlated with the existence of strong icosahedral short range order (ISRO) clusters in the structure