Crystallization behavior of a metallic glass Ni45Fe5Co20Cr10Mo4B16

The crystallization process and crystallizing temperature of metallic glasses are important for assessing the temperature range within which they can be applied. In this paper, the crystallization behavior of a metallic glass Ni45Fe5Co20Cr10Mo4B16 is reported, which was studied by hot-stage electron microscopy and differential scanning calorimetry. The influence of the defects due to irradiation on the crystallization temperature was studied by irradiating the specimens with 3.5 MeV electrons in a linear accelerator and 1 MeV electrons in a high voltage electron microscope. It was found that electron irradiation did not cause any noticeable change in the crystallizing process. The crystallization began at 390 +- 15 deg C, but the crystallization did not complete at this temperature, and the large crystallites embedded in amorphous matrix were observed. The precipitate was face centered cubic phase. At 508 +- 10 deg C, the second stage crystallization occurred, and the structure was body centered cubic structure. This time, the crystallization was complete. The specimens which were nonmagnetic in amorphous state became magnetic after the precipitation of the bcc phase. The heat of crystallization was 348 and 406 cal/mole for the first and second stages, respectively. (Kako, I.)