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Influence of Hydrostatic Pressure on the t → o Transformation in Mg‐PSZ Studied by In Situ Neutron Diffraction
Author(s) -
Kisi Erich H.
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02402.x
Subject(s) - neutron diffraction , hydrostatic pressure , thermal expansion , tetragonal crystal system , materials science , phase (matter) , diffraction , hydrostatic equilibrium , thermodynamics , transformation (genetics) , crystallography , analytical chemistry (journal) , chemistry , composite material , physics , optics , biochemistry , organic chemistry , chromatography , quantum mechanics , gene
The influence of hydrostatic pressure on the t → o transformation in Mg‐PSZ has been studied using a series of neutron diffraction measurements on samples cooled to cryogenic temperatures. A hydrostatic pressure of 400 MPa led to the t → o onset temperature being depressed by 75 K, and the yield of o phase at the base temperature (40 K) being halved. This lends support to the notion that the t particles in this system are predisposed to undergo the t → o transformation by thermal expansion mismatch stresses. It is estimated from thermal expansion data that the mismatch stresses could be as high as 760 MPa along the c ‐axis of the tetragonal precipitates and that the mismatch strains are qualitatively very similar to the transformation strains for the t → o transformation. It is proposed that the critical factor in determining the transformation path ( t → o vs t → m ) is the presence, in multiphase systems, of a coherent interface between the t phase and the surrounding phases.