Predictability of bulk metallic glass forming ability using the criteria based on characteristic temperatures of alloys

The criteria of glass forming ability (GFA) based on characteristic temperatures (CTs) of alloys offer an easy way to estimate the GFA of bulk metallic glasses (BMGs). However, recent researches have been more preoccupied with the correlations between the criteria and the critical cooling rate Rc than those between criteria and critical diameter Zmax although Zmax is the most crucial parameter in applications. In this study, nine different alloy systems were analyzed separately and the correlations between the criteria and Rc and/or Zmax were evaluated intensively. The results reveal that the criteria-Zmax distribution strongly depends on the alloy system and for some systems this distribution is totally random. The use of CTs-based criteria to predict GFA, defined by the maximum diameter of obtainable totally amorphous rod, is still questionable for some systems including Fe-, and Zr-based alloys. Several experiments have been run to verify our statistic analysis. It is shown that predictions using γ, γc and γm calculated from thermal analysis results totally agree with the X-ray diffraction results for the studied alloy systems.