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Thermodynamic Model for the Hysteresis in Metal-Hydrogen Systems.

DE2001763368

Publication Date	2000
Personal Author	Schwarz, R. B.; Khachaturyan, A. G.
Page Count	21
Abstract	A phenomenon common to most metalhydrogen systems is the presence of hysteresis in their cyclic absorption/resorption characteristics. Because hysteresis on a reversible transformation is indicative of a dissipative mechanism, early models (1) attributed the hysteresis to the plastic deformation needed to accommodate the volume change upon hydride formation. A friction model, however, cannot explain the reproducibility of the hysteresis over thousand of cycles. We propose that the hysteresis is an intrinsic thermodynamic phenomenon caused by the coherency strains between the parent metal phase and the transformed hydride phase. In this paper, we summarize the salient features of the model and explain its relevance to known metalhydrogen systems.
Keywords	Hysteresis Thermodynamic model Free energy Transforming phases Quantitative expressions Hydrogen Metals
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	99F - Physical & Theoretical Chemistry
Corporate Authors	Los Alamos National Lab., NM.; Department of Energy, Washington, DC.
Document Type	Conference Proceedings
NTIS Issue Number	200124
Contract Number	W-7405-ENG-36

Thermodynamic Model for the Hysteresis in Metal-Hydrogen Systems.

Thermodynamic Model for the Hysteresis in Metal-Hydrogen Systems.
DE2001763368

Publication Date	2000
Personal Author	Schwarz, R. B.; Khachaturyan, A. G.
Page Count	21
Abstract	A phenomenon common to most metalhydrogen systems is the presence of hysteresis in their cyclic absorption/resorption characteristics. Because hysteresis on a reversible transformation is indicative of a dissipative mechanism, early models (1) attributed the hysteresis to the plastic deformation needed to accommodate the volume change upon hydride formation. A friction model, however, cannot explain the reproducibility of the hysteresis over thousand of cycles. We propose that the hysteresis is an intrinsic thermodynamic phenomenon caused by the coherency strains between the parent metal phase and the transformed hydride phase. In this paper, we summarize the salient features of the model and explain its relevance to known metalhydrogen systems.
Keywords	Hysteresis Thermodynamic model Free energy Transforming phases Quantitative expressions Hydrogen Metals
Source Agency	Technical Information Center Oak Ridge Tennessee
NTIS Subject Category	99F - Physical & Theoretical Chemistry
Corporate Authors	Los Alamos National Lab., NM.; Department of Energy, Washington, DC.
Document Type	Conference Proceedings
NTIS Issue Number	200124
Contract Number	W-7405-ENG-36