Thermal behavior of Fe40Co8Cr15Mo13Y2C16B6 bulk metallic glass with reference to irreversible structural relaxation

• We studied thermal behavior of Fe-based BMG using dilatometry and DTA.
• Dilatometry is proposed as a precise method to determine the glass transition temperature in BMGs.
• Reversible and irreversible relaxation can be analyzed by dilatometry as well as measuring excess free volume.

Reversible and irreversible structural relaxation in the Fe40Co8Cr15Mo13Y2C16B6 bulk metallic glass (BMG) were studied and characterized via dilatometry. Glass transition and crystallization temperatures defined by dilatometry found to be in a good agreement with the results of Differential Thermal Analysis (DTA). Besides, the effect of irreversible structural relaxation on the free volume and the glass transition temperature was investigated. Results showed that the glass transition temperature for the as-cast samples in their dilation curves is more distinct compare to DTA, and temperatures at which structural relaxations occur can be well determined. It is also suggested that the difference in the dilatation of as-cast and relaxed sample can be a reliable method to measure the density of free volume in this BMG.