The phase diagram of molybdenum at extreme conditions and the role of local liquid structures

Ross, M

关键词: FREE ENERGY;    MELTING;    MOLYBDENUM;    PHASE DIAGRAMS;    POISSON RATIO;    VELOCITY;    X-RAY DIFFRACTION;   

DOI  :  10.2172/945533
RP-ID  :  LLNL-TR-406604
PID  :  OSTI ID: 945533
Others  :  TRN: US200904%%78

学科分类：物理（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

Recent DAC measurements made of the Mo melting curve by the x-ray diffraction studies confirms that, up to at least 110 GPa (3300K) melting is directly from bcc to liquid, evidence that there is no basis for a speculated bcc-hcp or fcc transition. An examination of the Poisson Ratio, obtained from shock sound speed measurements, provides evidence that the 210 GPa (4100K) transition detected from shock experiments is a continuation of the bcc-liquid melting, but is from a bcc-to a solid-like mixed phase rather than to liquid. Calculations, modeled to include the free energy of liquid local structures, predict that the transition from the liquid to the mixed phase is near 150 GPa(3500K). The presence of local structures provides the simplest and most direct explanation for the Mo phase diagram, and the low melting slopes.