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Centrifugal Atomization of Lanthanide Materials for Cryogenic Coolers

Description: Until recently, Pb was the preferred heat exchanger matrix material used in low temperature cryocoolers; however, the heat capacity of Pb drops drastically below {approximately}15K and new matrix materials based on the lanthanide elements have been developed. These materials magnetically order at low temperatures and the entropy change associated with ordering contributes to the materials` heat capacities. The drawback to widespread use of lanthanide intermetallic compounds in cryocoolers has b… more
Date: January 4, 1994
Creator: Osborne, Matthew G.
Partner: UNT Libraries Government Documents Department
open access

Low frequency ultrasonic nondestructive inspection of aluminum/adhesive fuselage lap splices

Description: This thesis is a collection of research efforts in ultrasonics, conducted at the Center for Aviation Systems Reliability located at Iowa State University, as part of the Federal Aviation Administration`s ``Aging Aircraft Program.`` The research was directed toward the development of an ultrasonic prototype to inspect the aluminum/adhesive fuselage lap splices found on 1970`s vintage Boeing passenger aircraft. The ultrasonic prototype consists of a normal incidence, low frequency inspection tech… more
Date: January 4, 1994
Creator: Patton, T.
Partner: UNT Libraries Government Documents Department
open access

Studies of high temperature ternary phases in mixed-metal-rich early transition metal sulfide and phosphide systems

Description: Investigations of ternary mixed early transition metal-rich sulfide and phosphide systems resulted in the discovery of new structures and new phases. A new series of Zr and Hf - group V transition metal - sulfur K-phases was synthesized and crystallographically characterized. When the group V transition metal was Nb or Ta, the unit cell volume was larger than any previously reported K-phase. The presence of adventitious oxygen was determined in two K-phases through a combination of neutron scat… more
Date: January 4, 1994
Creator: Marking, G. A.
Partner: UNT Libraries Government Documents Department
open access

Studies on the Optimization of Deformation Processed Metal Metal Matrix Composites

Description: A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New… more
Date: January 4, 1994
Creator: Ellis, Tim W.
Partner: UNT Libraries Government Documents Department
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