Thermal analysis of non-equilibrium crystallization in undercooled liquid Pd–Cu–Ni–P

The attention of the research on metallic glasses has focussed recently on the newly developed system Pd–Cu–Ni–P which exhibits a superior glass-forming ability—most notably the alloy with the composition Pd43Cu27Ni10P20. Due to the sluggish crystallization kinetics at deep undercooling, the resistance to crystallization can be significantly improved by suppressing heterogeneous nucleation with glass-fluxing technique. As a result, a cooling rate as low as 0.05 K/s is sufficient for vitrification of the melt as it is demonstrated experimentally by differential scanning calorimetry. Furthermore, thermal analysis of the crystallization processes reveals that the kinetics of the crystallization in the supercooled state depends strongly on the distinct crystalline phases formed in the different undercooling ranges. The crystallization kinetics in the highly viscous liquid at deep undercooling seems to be hindered by formation of the ordered Cu3Pd phase. In samples solidified without undercooling, typical eutectic structures with precipitation of Cu3Pd, Pd5Cu3P2, Pd3Ni2P2, (Pd0.9Ni0.1)3CuP, and [PdNiCu]3P are identified by SEM investigation.