The research team analyzed a large number of binary, ternary, and higher-order metallic glasses to validate the prediction of preferred radius ratios in the constitution of metallic glasses. The results showed a clear preference for the predicted critical radius ratios for all major classes of metallic glasses analyzed. The research team formed the following conclusions: (1) efficient atomic packing in the first coordination shell is a fundamental consideration in the constitution of metallic glasses; (2) researchers can predict specific critical radius ratios to provide efficient atomic packing in the first coordination shell of solute-centered atomic clusters; and (3) analysis of a large number of metallic glasses and a selected number of silicate glasses shows a strong preference for these predicted critical radius ratios.

This predictive model provides detailed guidance for selecting new alloys that may ultimately become the next generation of bulk metallic glasses. By selecting alloys with elements that satisfy predicted radius ratios, US scientists recently devised at least three new bulk metallic glass systems, including an iron-based glass that researchers are evaluating as a corrosion-resistant layer for nuclear waste containment.

Dr. Daniel B. Miracle, Capt Wynn S. Sanders, PhD, Dr. Oleg N. Senkov (Universal Energy Systems Corporation), and Dr. Peter S.Meltzer (Anteon Corporation), of the Air Force Research Laboratory’s Materials and Manufacturing Directorate, wrote this article. For more information, contact TECH CONNECT at (800) 203-6451 or place a request at http://www.afrl.af.mil/techconn/index.htm. Reference document ML-H-05-05.