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Experimental constraints on the phase diagram of elemental zirconium |
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| Authors: | Jianzhong Zhang Yusheng Zhao Jiang Qian Paulo A Rigg Carl W Greeff Yunpeng Yang Yanbin Wang |
| Institution: | a LANSCE Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA b T, DX, and MST Divisions, Los Alamos National Laboratory, Los Alamos, NM 87545, USA c Mineral Physics Institute, State University of New York, Stony Brook, NY 11794, USA d GESCARS, Advanced Photon Source of Argonne National Laboratory, University of Chicago, IL 60637, USA |
| Abstract: | The phase diagram of zirconium metal has been studied using synchrotron X-ray diffraction and time-of-flight neutron scattering at temperatures and pressures up to 1273 K and 17 GPa. The equilibrium phase boundary of the α-ω transition has a dT/dP slope of 473 K/GPa, and the extrapolated transition pressure at ambient temperature is located at 3.4 GPa. For the ω-β transition, the phase boundary has a negative dT/dP slope of 15.5 K/GPa between 6.4 and 15.3 GPa, which is substantially smaller than a previously reported value of −39±5 K/GPa in the pressure range of 32-35 GPa. This difference indicates a significant curvature of the phase boundary between 15.3 and 35 GPa. The α-ω-β triple point was estimated to be at 4.9 GPa and 953 K, which is comparable to previous results obtained from a differential thermal analysis. Except for the three known crystalline forms, the β phase of zirconium metal was found to possess an extraordinary glass forming ability at pressures between 6.4 and 8.6 GPa. This transformation leads to a limited stability field for the β phase in the pressure range of 6-16 GPa and to complications of high-temperature portion of phase diagram for zirconium metal. |
| Keywords: | A Metals A Amorphous materials C X-ray diffraction D Phase transitions C High pressure |
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