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The phase diagram of Ti-6Al-4V at high-pressures and high-temperatures

DOI: 10.1088/1361-648X/abdffa DOI Help

Authors: Simon Macleod (Atomic Weapons Establishment) , Daniel Errandonea (Universidad de Valencia) , Geoffrey Adam Cox (Atomic Weapons Establishment) , Hyunchae Cynn (Lawrence Livermore National Laboratory) , Dominik Daisenberger (Diamond Light Source) , Sarah Finnegan (The University of Edinburgh) , Malcolm Mcmahon (The University of Edinburgh) , Keith Munro (The University of Edinburgh) , Catalin Popescu (CELLS-ALBA Synchrotron Light Facility) , Christian Storm (The University of Edinburgh)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Journal Of Physics: Condensed Matter

State: Published (Approved)
Published: January 2021
Diamond Proposal Number(s): 8176 , 9366

Abstract: We report results from a series of diamond-anvil-cell synchrotron X-ray diffraction and largevolume- press experiments, and calculations, to investigate the phase diagram of commercial polycrystalline high-strength Ti-6Al-4V alloy in pressure-temperature space. Up to ~30 GPa and 886 K, Ti- 6Al-4V is found to be stable in the hexagonal-close-packed, or alpha phase. The effect of temperature on the volume expansion and compressibility of alpha-Ti-6Al-4V is modest. The martensitic alpha→omega (hexagonal) transition occurs at ~30 GPa, with both phases coexisting until further compression to ~38-40 GPa completes the transition to the omega phase. Between 300 K and 844 K the alpha→omega transition appears to be independent of temperature. Omega-Ti-6Al-4V is stable to ~91 GPa and 844 K, the highest combined pressure and temperature reached in these experiments. Pressure-volume-temperature equations-of-state for the alpha and omega phases of Ti- 6Al-4V are generated and found to be similar to pure Ti. A pronounced hysteresis is observed in the omega-Ti-6Al-4V on decompression, with the hexagonal structure reverting back to the  alpha phase at pressures below ~9 GPa at room temperature, and at a higher pressure at elevated temperatures. Based on our data, we estimate the Ti-6Al-4V alpha-beta-omega triple point to occur at ~900 K and 30 GPa, in good agreement with our calculations.

Diamond Keywords: Alloys

Subject Areas: Materials, Physics

Instruments: I15-Extreme Conditions

Other Facilities: MSPD at ALBA

Added On: 01/02/2021 11:34

Discipline Tags:

Materials Engineering & Processes Physics Hard condensed matter - structures Materials Science Engineering & Technology

Technical Tags: