Lowering critical cooling rate for forming bulk metallic glass

Small volumes of Pd44 Ni10 Cu26 P20 and Pd43.2 Ni8.8 Cu28 P20 were encapsulated in B2 O3 and thermally cycled between Tg -60 °C and Tl +60 °C, where Tg and Tl denote the alloys' glass transition and liquidus temperatures. After this thermal treatment, the critical cooling rates (CCRs) for glass formation can be lowered by an order of magnitude, resulting in a critical cooling rate significantly lower than that reported for any other glass forming alloy melt. These experiments demonstrate that the CCR is not constant but strongly dependent on the degree of heterogeneous nucleation.