Chemical stability of superhard rhenium diboride at oxygen and moisture ambient environmental conditions prepared by mechanical milling

In this study, rhenium diboride (ReB2) was obtained by mechanosynthesis at 640 minutes of milling. The obtained ReB2 was stored at oxygen and moisture ambient environmental conditions to know the chemical stability. The results indicate that ReB2 is totally decomposed at oxygen and moisture ambient environmental conditions. Furthermore, the X‐ray diffraction (XRD) analysis of ReB2 samples after 26 months of storage shows that the final products of degradation are HReO4 (liquid), H3BO3, HBO2, and ReO3. Finally, a schematic diagram of the degradation sequence of ReB2 at oxygen and moisture ambient environmental conditions is proposed and validated with a thermodynamic analysis.