On the Tendency of the Co-, Ni-, and Fe-Based Melts to the Bulk Amorphization

In this article, the influence of the liquid phase state on the glass-forming ability and solidification processes of the Co65.5Fe6.5Si18B10, Ni64.4Fe4Cr4.9Mn2B16.2C0.5Si8, and Fe50Cr15Mo14C15B6 alloys was studied. It was shown that in conditions of quenching from the melt at ~103 K/s, the largest fraction of the amorphous phase is achieved by cooling from a narrow temperature range near 1573 K (1300 °C) for Co65.5Fe6.5Si18B10, 1503 K (1230 °C) for Ni64.4Fe4Cr4.9Mn2B16.2C0.5Si8, and 1653 K (1380 °C) for Fe50Cr15Mo14C15B6. It was found that at these temperatures, there are anomalies in the viscosity and undercooling polytherms caused by changes in short-range ordering in these melts. Overheating the Co65.5Fe6.5Si18B10, Ni64.4Fe4Cr4.9Mn2B16.2C0.5Si8, and Fe50Cr15Mo14C15B6 melts above these temperatures is accompanied by changing the nature of their crystallization. It was shown that the analysis of the temperature dependences of undercooling and kinematic viscosity can be used to determine the optimum temperatures of the melts quenching to achieve their best bulk amorphization.