Strength and elastic moduli of TiN from radial x-ray diffraction under nonhydrostatic compression up to 45 GPa

Abstract

The high pressure behavior of titanium nitride (TiN) was investigated using synchrotron radial x-ray diffraction (RXRD) under nonhydrostatic compression up to 45.4 GPa in a diamond-anvil cell. We obtained the hydrostatic compression equation of state of TiN. Fitting to the third-order Birch–Murnaghan equation of state, the bulk modulus derived from nonhydrostatic compression data varies from 232 to 353 GPa, depending on angle ψ, the orientation of the diffraction planes with respect to the loading axis. The RXRD data obtained at ψ=54.7° yield a bulk modulus K0=282±9 GPa with pressure derivative K0′ fixed at 4. We have analyzed the deformation mechanisms by analyzing the (111), (200), (220), (311), and (222) peaks in the x-ray diffraction under pressures. The ratio of uniaxial stress component to shear modulus t/G ranges from 0.007–0.027 at the pressure of 6.4–45.4 GPa. It was found that the TiN sample could support a maximum uniaxial stress component t of 8.6 GPa, when it started to yield at 45.4 GPa under uniaxial compression. And the aggregate elastic moduli of TiN at high pressure were determined from the synchrotron RXRD measurements.