Analysis of the relaxation time of the glass forming liquids at near liquidus temperatures was conducted, correlation between the critical cooling rate for glass formation, fragility of the glass forming liquid, and reduced glass transition temperature was identified, and a glass forming ability (GFA) parameter $(F_1=2{[(m∕m_{\min })(1∕T_{\mathit{rg}}-1)+2]}^{-1})$ was proposed. This GFA parameter, which increases with a decrease in the critical cooling rate, is a function of the reduced glass transition temperature $T_{\mathit{rg}}$ and a fragility index $m$, and it varies from $\sim 0$ in the case of extremely fragile liquid to $2T_{\mathit{rg}}∕(1+T_{\mathit{rg}})$ in the case of extremely strong liquid. An exponential relationship between the critical cooling rate for glass formation and the parameter $F_1$ was identified and verified using available experimental data for metallic and nonmetallic glasses.

• Received 24 May 2007

DOI:https://doi.org/10.1103/PhysRevB.76.104202