Experimental constraints on the phase diagram of titanium metal |
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Authors: | Jianzhong Zhang Yusheng Zhao George T Gray III Wataru Utsumi Hattori Takanori |
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Institution: | a Los Alamos National Laboratory, Los Alamos, NM 87545, USA b Mineral Physics Institute, State University of New York, Stony Brook, NY 11794, USA c Synchrotron Radiation Research Center, Japan Atomic Energy Research Institute, Hyogo 679-5148, Japan |
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Abstract: | The phase transformations of titanium metal have been studied at temperatures and pressures up to 973 K and 8.7 GPa using synchrotron X-ray diffraction. The equilibrium phase boundary of the α-ω transition has a dT/dP slope of 345 K/GPa, and the transition pressure at room temperature is located at 5.7 GPa. The volume change across the α-ω transition is ΔV=0.197 cm3/mol, and the associated entropy change is ΔS=0.57 J/mol K. Except for ΔV, our results differ substantially from those of previous studies based on an equilibrium transition pressure of 2.0 GPa at room temperature. The α-ω-β triple point is estimated to be at 7.5 GPa and 913 K, which is comparable with previous results obtained from differential thermal analysis and resistometric measurements. An update, more accurate phase diagram is established for Ti metal based on the present observations and previous constraints on the α-β and ω-β phase boundaries. |
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Keywords: | A Metals C High pressure C X-ray diffraction D Phase transitions D Thermodynamic properties |
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