| Popis: |
Thirty-one single crystals of synthetic forsterite, Fo 100 , were deformed in 69 compressional creep tests in a 0.1-MPa confining atmosphere of H 2 + Ar. Temperature ranged from 1753 to 2023 K and stress σ (= σ 1 - σ 3 ) from 1.5 to 37.8 MPa. Steady-state creep under these conditions follows an empirical law of the form: strain rate ϵ = A zigma; n exp ( −Q RT ) where A , n , and Q are constants. General characteristics of Fo 100 creep — uniformity of strain, shape change as a function of orientation of σ, relative deformation resistance of different orientations — match those of natural olivine single crystals of composition Fo 92 . Specific constants in the flow law, however, are distinctly new: for σ oriented along [111] c (equidistant from the three principal crystallographic axes), values for Fo 100 are n = 2.9 ± 0.2 and Q = 0.67 ± 0.03 MJ/mol (160 ± 7 kcal/mol). A single law covers the range 3 σ T c orientation is typically |
