Thermal stability of cryomilled nanocrystalline aluminum containing diamantane nanoparticles
- 298 Downloads
The thermal stability of nanoscale grains in cryomilled aluminum powders containing 1% diamantane was investigated. Diamantane is a diamondoid molecule consisting of 14 carbon atoms in a diamond cubic structure that is terminated by hydrogen atoms. The nanostructures of the resulting cryomilled powders were characterized using both transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The average grain size was found to be on the order of 22 nm, a value similar to that obtained for cryomilled Al without diamantane. To determine thermal stability, the powders were heated in an inert gas atmosphere at constant temperatures between 423 and 773 K (0.51Tm to 0.83Tm) for exposure times of up to 10 h. The average grain size for all powders containing diamantane was observed to remain in the nanocrystalline range (1–100 nm) for all exposures and was generally less than half of that for cryomilled pure Al heated under the same conditions. The thermal stability data were found to be consistent with a grain growth model based on drag forces exerted by dispersed particles against grain boundary migration. The present findings indicate that the presence of diamantane results in a substantial increase in the thermal stability of nanoscale grains in Al.
KeywordsTransmission Electron Microscopy Micrographs Aluminum Powder Diamantane Thermal Exposure Lower Temperature Regime
This study was supported by the National Science Foundation (Grant No DMR-0702978) and the UC Discovery Program with matching support from the Boeing Company (Award No. GCP07-10250). The authors wish to also acknowledge assistance from Dr. W. A. Chiou of the Univ. of Maryland, Dr. J. Greaves of the UC Irvine Mass Spectrometry Facility as well as Gloria Chow and Dr. Robert Carlson of ChevronTexaco Technology Ventures, LLC for their generous assistance in this study.
- 10.Segal VM, Reznikov VI, Drobyshevskiy AE, Kopylov VI (1981) Metally 1:11523Google Scholar
- 13.Shewmon PG (1969) Transformation in metals. McGraw-Hill, New YorkGoogle Scholar
- 17.Burke JE (1949) Trans TMS-AIME 180:73Google Scholar
- 20.Yamasaki T (2000) Mater Phys Mech 1:127Google Scholar
- 26.Beck PA, Towers J, Manly WD (1947) Trans TMS-AIME 175:162Google Scholar