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Thermally Activated Martensitic Transformations in Mg‐PSZ
Author(s) -
Behrens Gesa,
Heuer Arthur H.
Publication year - 1996
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.1151-2916.1996.tb08523.x
Subject(s) - tetragonal crystal system , materials science , monoclinic crystal system , raman spectroscopy , orthorhombic crystal system , martensite , diffusionless transformation , indentation , plasticity , crystallography , residual stress , composite material , metallurgy , thermodynamics , microstructure , crystal structure , chemistry , physics , optics
The thermally activated, stress‐assisted martensitic tetragonal → monoclinic ( t → m ) and tetragonal → orthorhombic ( t → o ) transformations in a high‐toughness Mg‐PSZ were investigated by monitoring the phase assemblage with Raman spectroscopy after a variety of heat treatments and loading conditions. After a short anneal at 1000°C, which transforms m ‐ and o ‐ZrO 2 to the t polymorph, isothermal t → m and t → o transformations occur at room temperature during the months following the anneal. The transformation rates in the annealed samples are greatly enhanced under external stress. Alternatively, samples containing regions of significant residual stress, introduced by indentation for example, and then annealed at relatively low temperatures, underwent additional thermally activated transformation in the stressed regions. The thermodynamics and kinetics of this complex transformation “plasticity,” and its effect on mechanical properties, are discussed.