Research on Materials for High Power Laser Windows
Abstract
The theory for impurity drag on the grain boundary mobility in KCl has been modified to include a secondary interaction force such as would result from a size misfit between the solute and matrix ions. For aliovalent solutes the interactions are coupled. Near the isoelectric temperature the modified drag is much greater than that predicted for an electrostatic interaction. A simplified model has been developed which indicates the conditions under which a fluctuation in velocity along a boundary may grow and cause a segment of boundary to make the transition between the low and high velocity modes. Forged CaF2 samples have been examined by optical and transmission electron microscopy. There is a subgrain structure and the subgrain size decreases with increasing flow stress. Recrystallization which removes the subgrains can also occur during forging and during cooling. Recrystallization has been observed at temperatures as low as 600 C and is a serious problem above 800 C for pure samples.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1976
- Accession Number
- ADA044059
Entities
People
- F. A. Mcclintock
- H. K. Bowen
- J. B. Vander Sande
- R. M. Cannon
Organizations
- Massachusetts Institute of Technology