Predicting alloy compositions of bulk metallic glasses with high glass-forming ability

According to the vacancy formation energy (Delta H-h) in binary alloys, an easy approach for the computation of multi-component alloys is suggested. And the calculated Delta H-h values have linear correlation with the crystallization temperature (T-x) in Ca-Mg-Cu, Mg-Cu-Gd, Zr-Ni-Al and Cu-Zr-Ti alloying systems. Based on the relationship between Gibbs free energy (Delta G) and the liquidus temperature (T-I) and the glass-forming ability (GFA) indicator alpha (=T-x/T-I), a new expression containing Delta H-h, mixing entropy (Delta H-mix) and configurational enthalpy (S-config) for estimation of GFA is defined as Delta H-h Delta(HSconfig)-S-mix. The predicted composition lines derived with this expression are all very near the reported BMGs in La-Al-Co, Zr-Cu-Be, Ca-Mg-Zn and Cu-Zr-Ti alloying systems, respectively. Moreover, values of Delta H-h Delta(HSconfig)-S-mix is found to have a strong correlation with the critical diameters in La-Ce-Al-Co quarternary alloying system. Finally, three BMGs with Cu-rich compositions in Cu-Zr-Al alloying system are prepared and the experimental result about GFA is consistent with the computational Delta H-h Delta(HSconfig)-S-mix values. (C) 2007 Published by Elsevier B.V.