MAGNETIC ENERGY STORAGE AND CRYOGENIC ALUMINUM MAGNETS.
NATIONAL BUREAU OF STANDARDS BOULDER COLO CRYOGENICS DIV
Pagination or Media Count:
Factors pertaining to aluminum magnet technology have been investigated. Industrial competence and capacity to produce super-purity aluminum have been improved. Methods of analyzing super-purity aluminum have been studies in particular, the eddy-current decay technique of measuring electrical resistivity ratios between 4 and 295 degrees K have been improved and used extensively. New devices used to sensitively measure stress, strain, and resistivity at 4 degrees K have been developed. Two major experimental programs were conducted. One pertains to the effects of internal defects, particularly grain boundaries and impurity elements, on the residual resistance ratio. It was found that no one process can be ascribed to the linear relationship between increasing grain size and decreasing resistance ratio. One significant mechanism proposed is that, in super-purity aluminum, grain boundary motion acts to sweep away impurity elements in solid solution, thus having a purifying effect. The second program involved the relationships between applied stress, plastic strain, and electrical resistivity changes due to the introduction of dislocations and vacancies at 4 degrees K. It was found that the change in resistivity at 4 degrees K is related to epsilon to the 1.19 power where epsilon is the plastic strain. Author
- Electrical and Electronic Equipment
- Metallurgy and Metallography
- Electricity and Magnetism