Impeding effect of air bubbles on normal grain growth of ice

Making EBSD on water ice routine

“…Two data sets for grain growth are used. One relates to bubble‐free ice (Azuma et al ., ) with a growth exponent (n) of 2, activation energy for grain growth (Q) of 113 kJ mol ‐1 and a pre‐exponential (k 0 ) of 3 × 10 17 mm 2 s ‐1 (in the T range 0˚C to −40˚C calculated from Fig. in Azuma et al ., ).…”

“…One relates to bubble‐free ice (Azuma et al ., ) with a growth exponent (n) of 2, activation energy for grain growth (Q) of 113 kJ mol ‐1 and a pre‐exponential (k 0 ) of 3 × 10 17 mm 2 s ‐1 (in the T range 0˚C to −40˚C calculated from Fig. in Azuma et al ., ). The second data set relates to a compilation of grain‐growth estimates from glacial ice (in the T range −15˚C to −50˚C: Cuffey & Paterson, ) with n = 2, Q = 42 kJ mol ‐1 and k 0 = 1 mm 2 s ‐1 .…”

“…Graph to show the temperatures for a given time (labels on curves) that will give 1% grain growth for samples of different grain size. Calculations (section 1.2) are shown for normal grain growth of clean, bubble‐free ice (Az: Azuma et al ., ) and natural (bubbly and dirty) ice (Pa: Cuffey & Paterson, ).…”

“…Constraints on grain size kinetics have been limited by a narrow range in grain sizes used in experiments and from natural systems (Alley et al ., ). By far the best kinetic data on ice grain growth have come from recent experiments that use a fine‐grained starting material (Azuma et al ., ), using a sublimation etching method to see grain boundaries. Interaction with bubbles and particles is clearly important in natural terrestrial ice (Azuma et al ., ; Faria et al ., ; Roessiger et al ., ) and further experiments are needed.…”

“…The initial motivation for the work presented in this paper was to characterize the microstructures of fine‐grained ice, with grain sizes between a few and a few hundred micrometres. Fine‐grained ice samples are essential to explore grain size‐sensitive creep and grain‐growth behaviour over practical laboratory time scales (Goldsby & Kohlstedt, ; Azuma et al ., ). Many of the methods listed in the previous paragraph are difficult to apply to fine‐grained ices, so we looked to electron backscatter diffraction (EBSD), the dominant method for quantitative microstructural analysis of metals (Humphreys, ; Schwartz et al ., ), ceramics (Saylor & Rohrer, ; Peruzzo et al ., ) and rocks (Prior et al ., , ), as a means of mapping ice microstructures.…”