The best glass-forming compositions in Al-Co(or Ni)-Y ternary systems

The present work aims at the investigation of the largest glass-forming abilities in the Al-Co(or Ni)-Y ternary systems. In the reduced isothermal sections of their ternary phase diagrams, the e/a-based composition line passes through three known phases, Al₅₀Co(or Ni)₅₀, Al₃₃Co(or Ni)₃₃Y₃₃ and α-Y. The atomic cluster-based criterion was incarnated into the Co(or Ni)₃Y₇-Al composition line. The crossing of the two composition lines gives the composition of Al₂₃Co(or Ni)₂₃Y₅₄. The critical diameters for a full glassy state are 4 mm and 3 mm for the Ni-bearing and Co-bearing alloys, respectively. Thermal analysis indicates that the compositions are not eutectic points. The characteristic thermodynamic parameters are T_g = 645 K, T_x = 694 K and T_g/T_m = 0.64 for Al₂₃Ni₂₃Y₅₄ and T_g = 648 K, T_x = 681 K and T_g/T_m = 0.63 for Al₂₃Co₂₃Y₅₄.