Specific heat inwestigation of bulk metallic glasses

摘要

The aim of the paper is measurements and analysis of specific heat (Cp) of bulk metallic glasses. The fabrication method and structure analysis were also described. The studies were carried out on FeCo-based glassy test pieces with the following composition: Fe_(36)Co_(36)B_(19.2)Si_4. Samples in form of rods were prepared by copper mould casting method. The structure was tested by X-ray diffraction method and scanning electron microscope observation (SEM). For determination of thermal properties the DTA and DSC method were used. Specific heat of amorphous samples was investigated by calorimetric method. The X-ray diffraction revealed that fabricated samples exhibit glassy structure. Broad diffraction halo could be seen for each tested sample. SEM observations show that fracture morphology is changed on the diameter of samples. Thermal analysis allows assigning liquidus temperature (TI). On the base of DSC curves glass transition temperature (Tg) and crystallization temperature (Tx) were determinate. Specific heat investigation show insignificant changes in temperature range from 30 K to Tg. Bulk glassy FeCo-based alloys which are fabricated by rapidly solidifying technique are very interesting engineering materials because of its unique mechanical and magnetic properties. They could be used in many applications. Specific heat is important in solidification process. This property is significant input-data in computer simulation of solidification process. It is important to investigate thermal properties of bulk metallic glasses (including Cp) in order to understand mechanism of structural relaxation, glass transition and crystallization sequences.