Liquid state dependent solidification of a Co-B eutectic alloy under a high magnetic field

The structure transition inside the Co-81.5at.%B alloy liquid has been studied by an in-situ magnetization measurement. A crossover was observed on the 1/M-T curve during the overheating process, indicating that a liquid-liquid structure transition (LLST) took place in the melt. Based on this information, the effects of LLST on the solidification behavior, microstructure and tribology property were investigated experimentally. The sample solidified with the LLST exhibits significantly different solidification behaviors, i.e., the nucleation undercooling and the recalescence extent are conspicuously enlarged, and the solidification time is shortened. As a result, the microstructure is effectively refined and homogenized, and the hardness and wear resistance are significantly enhanced. The present work might be helpful for not only theoretically understanding the influence of LLST on the solidification behavior but also providing an alternative approach to tailor the microstructure and properties.