University of California

Farghalli A Mohamed

James C Earthman

Rahul K Mishra

Indranil Roy

Thermal stability of cryomilled Al+1% diamantane was investigated in the temperature range of 423 to 773K. Diamantane is a nanosized hydrocarbon molecule with a 14 carbon atom diamond cubic framework that is terminated by hydrogen atoms. Following the cryomilling of the Al powders and diamantane cages, the average grain size characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The as-cryomilled grain sized was found to be of the order of 22 nm, essentially the same as that for Al cryomilled without diamantane. To determine thermal stability, the powders were sealed in glass tubes in an Ar atmosphere to avoid oxidation and contamination and annealed at different temperatures between 423 and 773K for different holding times. Following these treatments, the grain size of cryomilled Al+1% diamantane was consistently less than that for cryomilled Al by about a factor of two. Preliminary investigations indicate that the grain growth exponent n decreased with increasing temperature, reaching a value of approximately 35 at 423 K. Such a high value of n suggests the operation of strong pinning forces on boundaries during annealing treatment. The thermal stability data were found to be consistent with Burke's model based on drag forces exerted by dispersion particles.

Growing community of inventors

Huntington Beach, CA, United States of America

Farghalli A Mohamed