Materials Research for Advanced Inertial Instrumentation. Task 1. Dimensional Stability of Gyroscope Structural Materials.
Abstract
Additional microyield measurements on HIP-50 beryllium samples, subjected to a variety of selected heat treatments, were performed. It was determined that of the several treatments that were employed the most significant increase in the value of the microyield strength occurred from a 100 hour exposure to 600 C. A microyield value of about 26.5 klb/sq in. was measured after this treatment compared to an as-received value of 17.2 klb/sq in. Examination of the microyield data plotted on logarithmic coordinates showed that if a correlation is desired between the processes of microyield and microcreep, one must take into account the value of the strain exponent (which is the slope of the straight line) in the low strain regime, in addition to the measured value of the microyield strength. Experiments performed in this study showed that considerable care should be exercised in the preparation of samples for microstructure examination to avoid introducing mechanical damage in regions near the surface. Optical microscopy was found to have limited utility in determining the effects of the several thermal treatments on sample microstructure. Transmission electron microscopy, however, was successfully performed after jet-thinning the samples in a chromic-acetic acid electrolyte. The differences observed were mainly related to phase precipitation and segregation. Attempts to identify these precipitates are planned for the future.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1980
- Accession Number
- ADA098165
Entities
People
- F. Petri
- J. Mccarthy
- J. Wollam
- K. Kumar
Organizations
- Charles Stark Draper Laboratory