The equation of state of TaC0.99 by X-ray diffraction in radial scattering geometry to 32 GPa and 1073 K

Abstract

We have performed in situ synchrotron X-ray diffraction experiments on TaC0.99 compressed in a diamond anvil cell along 3 isothermal paths to maximum pressure (P)-temperature (T) conditions of 38.8 GPa at 1073 K. By combining measurements performed in axial diffraction geometry at 296 K and in radial geometry at 673 K and 1073 K, we place constraints on the pressure-volume-temperature (P-V-T) equation of state of TaC in a wide range of conditions. A fit of the Birch-Murnaghan equation to the measurements performed in axial geometry at ambient temperature yields a value of the isothermal bulk modulus at ambient conditions 0 = 305  5 (1) GPa and its pressure derivative (/) 0 = 6.1  0.5. The fit of the Birch-Murnaghan

An improved setup for radial diffraction experiments at high pressures and high temperatures in a resistive graphite-heated diamond anvil cell

“…Carbides are characterized by high mechanical and thermal stability and play an important role in industrial applications, where they are used, for example, as coatings for abrasive tools. Many experimental and computational studies have been conducted on tantalum carbide (see references in 51 ). However, no experiments have been performed to study the behavior of this phase under simultaneous high pressure, high temperature and deviatoric stress.…”

“…However, no experiments have been performed to study the behavior of this phase under simultaneous high pressure, high temperature and deviatoric stress. We performed two successful experimental deformation runs on tantalum carbide (TaC0.99) and constrained the pressure-volume-temperature equation of state 51 . The starting material was This is the author's peer reviewed, accepted manuscript.…”

“…In the second run, we increased temperature at a pressure of 2 GPa up to 1073 K, and we collected X-ray diffraction images up to a final pressure of ~38 GPa along an isothermal path. The data collected under non-hydrostatic conditions were used to constrain the quasi-hydrostatic high temperature EOS by extracting the hydrostatic unit-cell parameter from the x-ray diffraction data 53 . In addition these data can be used to determine the strength and activity of the slip systems of TaC0.99 at simultaneous high-pressure and -temperature (Speziale et al in prep.…”