Theory of the phase-change behavior of hydrogen in metals containing metallic impurities: The hydrogen–niobium–molybdenum system
1984; American Institute of Physics; Volume: 81; Issue: 9 Linguagem: Inglês
10.1063/1.448149
ISSN1520-9032
AutoresArthur I. Shirley, Carol K. Hall, Paramdeep S. Sahni, Nancy J. P. King,
Tópico(s)Advanced Chemical Physics Studies
ResumoA theory of the phase-change behavior of hydrogen in metals containing substitutional impurities is described. A lattice-gas model is developed which includes both direct electronic and indirect elastic interactions between hydrogen atoms. The interactions between hydrogen atoms and the randomly distributed impurity atoms are treated as a random field in analogy with the random field Ising model. The model is applied to the hydrogen–niobium–molybdenum system. Monte Carlo simulation is used to calculate the free energy and incoherent phase diagrams. The calculation predicts that even small amounts (5%–15%) of molybdenum cause the disappearance of the α–α′ coexistence region found in Nb–H. In addition the α–β transition, which is first order in Nb–H, becomes second order above a certain temperature (the tricritical point). These results are in qualitative agreement with experiment.
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