Embrittlement of titanium–zirconium ‘null-matrix’ alloy by deuterium

Abstract

Random substitutional Ti_2.08Zr exhibits zero Bragg scattering and alloys with this nominal composition are therefore used to fabricate pressure cells for neutron scattering measurements. Because Ti and Zr alloys are well known to be subject to hydrogen embrittlement, the embrittlement of Ti_2.001Zr by deuterium gas was investigated to assess its suitability for use in neutron diffraction experiments on samples under deuterium pressure. At 77°C, the alloy survived 15 days in 689 bar D₂ with no apparent effect on mechanical properties. At 100°C, however, embrittlement was initiated by 607-bar D₂, and at 200°C rapid decrepitation occurred, producing ϵ-(TiZr)D _x . It is therefore recommended that Ti_≈ 2Zr should not be considered for structural use with deuterium gas above room temperature.

Keywords:

• Titanium alloys
• Hydrogen embrittlement
• Mechanical properties
• Neutron diffraction

Acknowledgements

The authors thank M. R. Daymond (ISIS) for the mechanical testing data, R. B. Done (ISIS) for helpful consultations and L. Bekessy (Analytical Electron Microscopy Facility, Queensland University of Technology) for assistance with the SEM and EDS. Access to ISIS was supported by the Australian Research Council and the Access to Major Research Facilities programme.