Controlling mechanical performance and structural homogeneity of large-sized Zr-based bulk metallic glasses via mold temperature regulation

Overcoming the size limitations of bulk metallic glass (BMG) components remains a critical challenge for their industrial applications, necessitating fundamental insights into the casting process. This study investigates large-scale Zr-based metallic glasses, systematically exploring mechanical performance and structural homogeneity through mold temperature regulation under near-critical cooling conditions. As the mold temperature approaches the critical temperature threshold (573 K), the sample exhibit enhanced microhardness while retaining plasticity (0.72-1.85%). However, exceeding mold temperature (623 K) triggers mechanical degradation, indicating a ductile-to-brittle transition. Nanoindentation mapping analysis reveals that the transition originates from the reduction in structural heterogeneity and the precipitation of crystalline phases within the BMG matrix. To ensure optimal performance, it is essential to strictly maintain the mold temperature below 573 K. These findings demonstrate that precise control of mold temperature is crucial for optimizing the mechanical performance and microstructural characteristics of large-scale BMGs, providing valuable insights for enhancing their applications in advanced engineering fields.