Research on Materials for High Power Laser Windows
Abstract
The effects of aliovalent solutes on the grain boundary mobility of KC1 and of oxides has been studied. The previously developed model for boundary mobility in KC1 has been reformulated to include the effect of a strain energy interaction between the divalent solute ions and the boundary. Numerical calculations show that the solute ion and defect distributions, as well as the electrostatic field around a boundary are all affected. The theory predicts the resulting boundary drag will increase in order for Ba(+2), Sr(+2), to Ca(+2) solutes. A fluctuation mechanism by which a boundary can shed its solute cloud and move at intrinsic velocity has been analyzed. A survey of grain boundary mobility data in oxides was made to indicate the relative importance of various controlling mechanisms. CaF2 single crystals of various orientations have been forged over a range of 0.46 to 0.92 Tm. Optical and TEM studies of the microstructure revealed that subgrain formation occurs over the entire temperature range investigated. Models have been developed to calculate the effects of microcracking and crack coalescence on fracture statistics. A variety of methods for determining flaw distributions and detecting flaws have been investigated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1977
- Accession Number
- ADB025624
Entities
People
- F. A. Mcclintock
- H. K. Bowen
- J. B. Vander Sande
- R. M. Cannon
Organizations
- Massachusetts Institute of Technology