Browsing by Author "Bird, Marc W. 1984-"
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Item Creep Behavior of a Zirconium Diboride-Silicon Carbide Composite and Preliminary ZrB2-WC Quasi-Binary Alloy Development for Long Duty Cycle Aerosurfaces and Structural Propulsion Applications(2013-12) Bird, Marc W. 1984-; White, Kenneth W.; Becher, Paul F.; Sharma, Pradeep; Sun, Li; Wheeler, Lewis T.; Willam, Kaspar J.; Litvinov, Dmitri; Khator, Suresh K.The mechanical behavior of select ultra-high temperature ceramics were studied for extreme environment aerospace applications. Hot-pressed ZrB2-20 vol% SiC composites and ZrB2-WC quasi-binary alloys were developed for assessing room temperature mechanical properties and creep behavior. A thermochemical model describing alloy phase stability and reaction equilibria, for promoting WC dissolution, is presented. Room temperature structure-property relationships were developed correlating fracture strength and KIC with microstructure constituent size. Flexural creep studies of ZrB2-20 vol% SiC were conducted over the range of 1400°C to 1820°C assessing the macroscopic creep behavior using power-law stress and temperature dependent constants. Inert environment creep experiments were conducted for probing the local grain deformation mechanism in anticipation of bridging the deformation length scales. A two decade increase in creep rate, between 1500 and 1600°C, suggests a clear transition between the low temperature (1400-1500°C) diffusion creep and high temperature (>1600°C) grain boundary sliding creep having stress exponents of unity and 1.7