Studies of the Micromechanisms of the Flow and Fracture of Ice
Abstract
The goal of this work was to understand the behavior of dislocations around loaded notches in ice single crystals using x-ray topography and to study the effects of both orientation and impurities on the flow of ice single crystals. Ice single crystals were grown in Dartmouth's Ice Research Laboratory. For dislocation observations, stress-controlled in-situ deformation experiments were performed using an x-ray beam line at the National Synchrotron Light Source in collaboration with Dr. D. Black and Prof. M. Dudley. The observed dislocation motion around notches of different orientations was also modeled. Compression tests on high-purity ice single crystals of different orientation showed that Schmid's critical resolved shear stress law is well-obeyed in ice. It was also shown for the first time that a few p.p.m. of sulfuric acid markedly reduced both the peak strength and subsequent flow stress of ice single crystals at -20 deg C, and increased their ductility. Measurements of the chemistry of triple points and nodes in both laboratory-grown, sulfuric acid-doped ice and ice cores from Antarctica using x-ray microanalysis in a SEM have shown strong segregation in the former ice but little in the latter.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2000
- Accession Number
- ADA379066
Entities
People
- Ian Baker