Extremely low critical cooling rates of new Pd-Cu-P base amorphous alloys

A new Pd40Ni10Cu30P20 amorphous alloy subjected to the B2O3 flux treatment was found to have a maximum thickness above 50 mm and a low critical cooling (R-c) of 0.100 K s(-1). The R-c for the Pd-Ni-Cu-P alloy without the flux treatment is 1.58 K s(-1) and the decrease in R-c is due to the suppression of heterogeneous nucleation, in addition to the high T-g/T-m of 0.72 and Delta T-x(= T-x - T-g) of 98 K. These R-c values are smaller and the T-g/T-m and Delta T-x values are larger as compared with those (R-c = 140 K s(-1), T-g/T-m = 0.67 and Delta T-x = 63 K) for an unttuxed Pd40Ni40P20 amorphous alloy. The new alloy appears to lie around the eutectic point with a low T-m of 804 K and the crystallization occurs through a single stage accompanying the precipitation of Pd2Ni2P, Pd15P2, (Ni, Cu)(3)P and unknown compound. The finding of the new amorphous alloy with the lowest R-c, and the largest thickness isimportant for the future development of bulk amorphous alloys. (C) 1997 Elsevier Science S.A.