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Stress and temperature dependence of recrystallized grain size: A subgrain misorientation model
Author(s) -
Shimizu Ichiko
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1998gl900136
Subject(s) - misorientation , nucleation , materials science , grain size , recrystallization (geology) , thermodynamics , grain boundary diffusion coefficient , condensed matter physics , grain boundary , mineralogy , composite material , microstructure , physics , chemistry , geology , paleontology
The steady‐state grain size of Earth materials undergoing solid state flow is estimated based on a nucleation‐and‐growth model of dynamic recrystallization. Assuming a nucleation mechanism of subgrain rotation, the mean diameter d of recrystallized grains is obtained as d / b = A (σ/µ) − p exp[‐(( Q gb ‐ Q v )/ mkT )], where b is the length of the Burgers vector, σ is differential stress, µ is the shear modulus, Q gb is the activation energy for the jump of an atom across the grain boundary, Q v is that for self‐diffusion in the grain volume, k is the Boltzmann constant, T is temperature, A is a constant, p = 1.25 and m = 4 for intracrystalline nucleation, and p = 1.33 and m = 3 for grain‐boundary nucleation. The exponent p = 1.25 ∼ 1.33 agrees well with available data for high‐ temperature dislocation creep of rock‐forming minerals. A weak negative dependence of grain size on temperature is expected from this theory.