Undercooling Behavior and Critical Cooling Rate of Pd-Pt-Cu-P Alloy

摘要

In order to realize biomedical applications of bulk glassy alloys, we have developed new Pd-based glassy alloys with Ni-free composition in Pd-Pt-Cu-P system and it is revealed that the highest glass-forming ability is obtained at a composition of Pd_(35)Pt_(15)Cu_(30)P_(20). In addition, the alloy can be formed into bulk glassy rods with diameters of up to at least 30 mm by fluxed water quenching. In order to clarify the critical cooling rate for glass-formation, undercooling behavior and crystal growth rate are also discussed. Crystallization of the alloy under continuous cooling is mainly dominated by surface nucleation. Apparent crystal growth rate of the alloy at 0.73 T_m is evaluated to be 5.2 x 10~(-6) m centre dot s~(-1) and this value is four orders of magnitude higher than that of previous Pd_(40)Cu_(30)Ni_(10)P_(20) at the same degree of undercooling.