Trends in Bulk Compressibility of Mo2-x,WxBC Solid Solutions

The Mo(2)(-x)WxBC system is of interest as a material with high hardness while maintaining moderate ductility. In this work, synchrotron diffraction experiments are performed on Mo(2)(-x)WxBC solid solutions, where x = 0, 0.5, and 0.75, upon hydrostatic compression to similar to 54 GPa, similar to 55 GPa, and similar to 60 GPa, respectively. Trends in bulk modulus, K-0, are evaluated by fitting collected pressure-volume data with a third-order Birch-Murnaghan equation of state, finding K-0 = 333(9) GPa for Mo2BC, K-0 = 335(11) GPa for Mo1.5W0.5BC, and K-0 = 343(8) GPa for Mo1.25W0.75BC. While K-0 seems to express a slight increase when Mo is substituted by W, calculated zero-pressure unit cell volume, V-0, exhibits the opposite trend. The decrease in V-0 corresponds to an increase in valence electron density, hardness, and K-0. Observations align with previously reported computational results and will inform future efforts to design sustainable materials with exceptional mechanical properties.