High-temperature creep studies have been conducted on “recrystallized” nickel-tho ria alloys which contained various ThO2 particle sizes (220-550 Å dia.) and volume fractions (0.01-0.045). Creep results, together with structural studies employing electron microscopy, indicate that the rate-controlling creep process is the climb of edge dislocations over ThO2 particles. Calculations predict that the steady-state creep rate, έs, is related to particle size and spacing by εs ∝ d2/rv, where d is the mean planar centre-to-centre particle spacing, and rv is the average particle radius. This relation is in accord with experimental observations.
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