Synthesis of Highly Amorphous Fe70Ti2Y6B22 Bulk Alloy with Excellent Thermal Stability by Isothermal Compression under High Pressure

A highly amorphous Fe70Ti2Y6B22 bulk alloy, with a diameter of 3 mm and a height of 2 mm, was synthesized by applying isothermal compression from 10 to 15 GPa at 1473 K using mixed metal powder. The structural analyses by performing X-ray diffraction and transmission electron microscopy revealed that the alloy was composed of a glassy structure. According to the differential scanning calorimetry analysis, a large supercooled liquid region (Delta T-x) of approximately 550 K was obtained, which is caused by the highly densely packed structures of a highly amorphous Fe70Ti2Y6B22 bulk alloy. The value was six times the value obtained by rapid cooling. Also, the Vickers hardness of the sample was approximately 8.5 GPa at a loading force of 29.4 N. These results indicated that isothermal compression under high pressure is a feasible method for fabricating bulk metallic glasses satisfying large-size requirements.