Pressure-dependent structure of the null-scattering alloy Ti_0.676 Zr_0.324

Abstract

The room temperature structure of the alloy ${\mathrm{Ti}}_{0.676}{\mathrm{Zr}}_{0.324}$ was measured by X-ray diffraction under compression at pressures up to $\sim 30\mathrm{GPa}$. This alloy is used as a construction material in high pressure neutron-scattering research and has a mean coherent neutron scattering length of zero, that is, it is a so-called null-scattering alloy. A broad phase transition was observed from a hexagonal close-packed α-phase to a hexagonal ω-phase, which started at a pressure of $\lesssim 12\mathrm{GPa}$ and was completed by $\sim 25\mathrm{GPa}$. The data for the α-phase were fitted by using a third-order Birch–Murnaghan equation of state, giving an isothermal bulk modulus $B_0=87\left(4\right)\mathrm{GPa}$ and pressure derivative $B_0^{\mathrm{\prime }}=6.6\left(8\right)$. The results will help to ensure that accurate structural information can be gained from in situ high pressure neutron diffraction work on amorphous and liquid materials where the ${\mathrm{Ti}}_{0.676}{\mathrm{Zr}}_{0.324}$ alloy is used as a gasket material.

Keywords:

• high pressure
• equation of state
• X-ray diffraction
• neutron diffraction

Acknowledgements

We thank Robert Done (ISIS, UK) and Burkhard Annighöfer (CEA, France) for useful discussions on the properties of Ti–Zr alloys, and Keiron Pizzey (Bath) for helpful discussions on the Birch–Murnaghan equations of state.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

AZ and PSS were supported by the Engineering and Physical Sciences Research Council (EPSRC) via Grant No. EP/J009741/1. MG was fully supported by EFree, an Energy Frontier Research Center funded by the US Department of Energy (DOE) and Office of Science Basic Energy Sciences (BES) program under award DE-SC0001057. Data collection was conducted at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory, USA. HPCAT operations are supported by the DOE and National Nuclear Security Administration (NNSA) under Award No. DE-NA0001974 and by DOE-BES under Award No. DE-FG02-99ER45775, with partial instrument funding from the National Science Foundation (NSF). Use of the COMPRES-GSECARS gas loading system was supported by COMPRES under NSF Cooperative Agreement No. EAR 11-57758 and by GSECARS through NSF Grant No. EAR-1128799 and DOE Grant No. DE-FG02-94ER14466. APS is supported by DOE-BES under Contract No. DE-AC02-06CH11357.