High P-T phase transitions and P-V-T equation of state of hafnium

Rostislav Hrubiak, Vadym Drozd, Ali Karbasi, Surendra K. Saxena
2012 Journal of Applied Physics  
A cold energy mixture theory for the equation of state in solid and porous metal mixtures J. Appl. Phys. 110, 013506 (2011) High pressure Hugoniot measurements using converging shocks J. Appl. Phys. 109, 093520 (2011) Molecular dynamics study of the melting curve of NiTi alloy under pressure J. Appl. Phys. 109, 043503 (2011) Equation of state for aluminum containing helium bubbles We measured the volume of hafnium at several pressures up to 67 GPa and at temperatures between 300 to 780 K using
more » ... resistively heated diamond anvil cell with synchrotron x-ray diffraction at the Advanced Photon Source. The measured data allows us to determine the P-V-T equation of state of hafnium. The previously described [Xia et al., Phys. Rev. B 42, 6736-6738 (1990)] phase transition from hcp (a) to simple hexagonal (x) phase at 38 GPa at room temperature was not observed even up to 51 GPa. The x phase was only observed at elevated temperatures. Our measurements have also improved the experimental constraint on the high P-T phase boundary between the x phase and high pressure bcc (b) phase of hafnium. Isothermal room temperature bulk modulus and its pressure derivative for the a-phase of hafnium were measured to be B 0 ¼ 112.9 6 0.5 GPa and B 0 0 ¼ 3.29 6 0.05, respectively. P-V-T data for the a-phase of hafnium was used to obtain a fit to a thermodynamic P-V-T equation of state based on model by Brosh et al. [CALPHAD 31, 173-185 (2007)]. V C 2012 American Institute of Physics.
doi:10.1063/1.4726211 fatcat:f7rvac6c65ccjobsiy2im5lome