Contrasting viscoelastic behavior of melt-free and melt-bearing olivine: Implications for the nature of grain-boundary sliding
نویسندگان
چکیده
Melt-free and basaltic (complex alumino-silicate) melt-bearing specimens of fine-grained polycrystalline olivine (Mg0.9Fe0.1)2SiO4, tested at igh temperature and low frequency in torsional forced oscillation and microcreep, display markedly different behavior. For the melt-bearing aterials, superimposed upon the high-temperature background is a dissipation peak whose height varies systematically with melt fraction that is ttributed to elastically accommodated grain-boundary sliding facilitated by the rounding of grain edges at melt-filled triple junctions. The melt-free aterials display only the high-temperature background dissipation associated with transient diffusional creep—elastically accommodated sliding vidently being inhibited by their tight grain-edge intersections. These and similar observations for other ceramic materials require that the classic heory of grain-boundary sliding be revisited and suitably modified. 2006 Published by Elsevier B.V.
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