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Title: Phase diagram of Mo at high pressure and temperature

Abstract

We report values of the Poisson Ratios for shock compressed Mo, calculated from the sound speed measurements, which provide evidence that the 210 GPa ({approx}4100K) transition cannot be a bcc-hcp transition, as originally proposed. Instead, we find the transition is from the bcc to a noncrystalline phase. For pressures above 210 GPa, the Poisson Ratio increases steadily with increasing temperature, approaching the liquid value of 0.5 at 390 GPa({approx}10,000K), suggesting the presence of a noncrystalline solid-liquid mixture. Free energy model calculations were used to show that the low melting slope of Mo, and the phase diagram, can be explained by the presence of local liquid structures. A new phase diagram is proposed for Mo that is constrained by the experimental evidence.

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
945864
Report Number(s):
LLNL-TR-407689
TRN: US200904%%178
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUMM MECHANICS, GENERAL PHYSICS; FREE ENERGY; MELTING; PHASE DIAGRAMS; POISSON RATIO; VELOCITY

Citation Formats

Ross, M. Phase diagram of Mo at high pressure and temperature. United States: N. p., 2008. Web. doi:10.2172/945864.
Ross, M. Phase diagram of Mo at high pressure and temperature. United States. https://doi.org/10.2172/945864
Ross, M. 2008. "Phase diagram of Mo at high pressure and temperature". United States. https://doi.org/10.2172/945864. https://www.osti.gov/servlets/purl/945864.
@article{osti_945864,
title = {Phase diagram of Mo at high pressure and temperature},
author = {Ross, M},
abstractNote = {We report values of the Poisson Ratios for shock compressed Mo, calculated from the sound speed measurements, which provide evidence that the 210 GPa ({approx}4100K) transition cannot be a bcc-hcp transition, as originally proposed. Instead, we find the transition is from the bcc to a noncrystalline phase. For pressures above 210 GPa, the Poisson Ratio increases steadily with increasing temperature, approaching the liquid value of 0.5 at 390 GPa({approx}10,000K), suggesting the presence of a noncrystalline solid-liquid mixture. Free energy model calculations were used to show that the low melting slope of Mo, and the phase diagram, can be explained by the presence of local liquid structures. A new phase diagram is proposed for Mo that is constrained by the experimental evidence.},
doi = {10.2172/945864},
url = {https://www.osti.gov/biblio/945864}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Oct 01 00:00:00 EDT 2008},
month = {Wed Oct 01 00:00:00 EDT 2008}
}