A novel strategy to design Zr–Co–Al BMG composites containing only B2–ZrCo phase

Abstract

The B2 phase-containing Bulk Metallic Glass (BMG) composites, as a promising remedy to tackle the strain-softening and brittleness of BMGs, has been widely applied to enhance the work-hardening and plastic deformability. A novel strategy was proposed to select the composition of an alloy which effectively promotes the formation of B2–ZrCo phase. We designed and prepared six compositions and seven rod samples, and then analysed the precipitation of crystalline phase together with the mechanical properties. We found that the primary phases administrate the mechanical properties and the composition of an alloy determines the formation of crystalline phases. Also, the cooling rate cannot enhance the B2–ZrCo phase formation in as-cast Zr–Co–Al BMG composites. As a result, we found that the formation of a large quantity of glass matrix and only B2–ZrCo phase cannot be achieved simultaneously in as-cast Zr–Co–Al alloys. In order to resolve this issue, flash annealing has been introduced to solve this problem. Different compositions correspond to different critical heating rates and high heating rate usually aggravates the difficulty to achieve this aim. In order to reduce critical heating rate, the conventional annealing, which can be well controlled, was used to select the alloy composition and compare formation of the B2–ZrCo phase. And thus, an optimal composition of Zr–Co–Al alloy can be selected to produce the BMG composites incorporating the only B2–ZrCo phase via flash annealing. Therefore, we believe that this work provides a novel recipe to design the Zr–Co–Al BMG composites incorporating the only B2–ZrCo phase.