Effects of Thermal Exposure and Test Temperature on Structure Evolution and Hardness/Viscosity of an Iron-Based Metallic Glass

摘要

High-temperature microhardness testing on drop-cast ingots of fully amorphous Fe48Mo14Cr15Y2C15B6 was performed in order to determine the behavior and structure evolution of this Fe-bulk metallic glass under a variety of different test conditions. The effects of changes in test temperature on the microhardness/strength were determined over the temperature range from room temperature to 620 °C. Although high (e.g., >12 GPa) microhardness was exhibited at room temperature, significant hardness reductions were exhibited near T g . In addition, the effect of exposure time (up to 300 minutes) at elevated temperature on the evolution of microhardness/strength was also evaluated for selected temperatures between 25 °C and 620 °C. The microhardness results were complemented with X-ray diffraction (XRD), conventional transmission electron microscopy (TEM), and an in-situ heating TEM study in order to evaluate any structural evolution that could explain the large differences in hardness evolution under different test conditions.