Glass forming ability and in-situ composite formation in Pd-based bulk metallic glasses

Pd_60-xNi₁₀Cu₃₀P_x alloys with x=10-20 were prepared by chill-casting, Bridgman solidification and melt spinning, giving a cooling rate range from 0.63 to ∼10⁶ K/s. The effects of P content on the glass forming ability and in-situ bulk metallic glass (BMG) matrix composite formation in these alloys have been studied. Glass forming ability of the Pd-Ni-Cu-P alloys improves with increasing P content. This is interpreted in terms of the reduced glass transition temperature T_rg given by T_g/T_L and the crystallization rate constant K_T. F.c.c α-Pd crystalline phase reinforced BMG matrix composites have been synthesized in a wide range of compositions. The formation of the in-situ BMG matrix composite is explained qualitatively in terms of competition between eutectic growth and amorphous phase formation.