Low-temperature crystallization caused by ultrasound in Pd42.5 Ni7.5 Cu30 P20 and Pd40 Ni40 P20 bulk metallic glasses

Crystallization behavior of Pd42.5 Ni7.5 Cu30 P20 and Pd40 Ni40 P20 (number indicate at.%) bulk metallic glasses under ultrasonic (US) vibrations of sub/low-MHz frequencies has been systematically investigated. It was found that, when the glassy sample was subjected to the US vibrations for a long duration, the crystallization occurred even (near) below the glass transition temperature TgTg. The microstructural features of the US-accelerated crystalline phases are presented, and the mechanism of the US-accelerated crystallization is briefly discussed in terms of β relaxation.