Study On The X-Ray Rietveld Methods Of The Metallic Aluminum Content And Microstress In Aluminum Nanopowders

Aluminum nanoparticles instead of micron aluminum can significantly improve theenergy and combustion performance of energetic materials, which has become animportant research subject in the field of energetic materials. On the basis of thepreliminary studies by our group, the X-ray Rietveld whole pattern-fitting method wasused to analyze the metal aluminum content and the microstress in nano-aluminumpowder.Rietveld method is to use the calculation pattern to fit the experimental pattern andobtain corresponding information, so a suitable step width and scanning time is necessary.On the basis of the ideal structure model and the peak function, the effect of the step widthand the counting time on index factors was studied. It was found that the optimumcounting time for nano-aluminum powders date collection was40s, where the changingstep width has not affect on index factors. And R factors had relatively small values at thestep widths before0.02°, which is the priority step width. Finally, the reason about theinfluence of the step width and scanning time on the index factors was explain.The content of metal Al in three kinds of nano-aluminum powders synthesizedrespectively by wire electrical explosion (Al-E), plasma (Al-P) and laser-inductioncomplex heating method (Al-L) was analyzed by the X-ray Rietveld quantitative phaseanalysis method. When a good agreement between the observed and calculated diffractionpattern was obtained and the index factors converged to satisfactory value, the mentalaluminum content is91.88%in Al-E,95.79%in Al-P and43.31%in Al-L. And themixture sample of micro aluminum and aluminum oxide (Al2O3) that weight fraction wasknown was tested by this Rietveld method to verify the reliability of refinement results.The microstress in Al-E, Al-P and Al-L were analyzed by the X-ray Rietveld peakwidth fitting method. The microstrain value in Al-E is5.517%,4.367%in Al-L and 2.168%in Al-P. At the same time, the lattice constant information was obtain, the latticeconstant is4.043712in Al-E,4.047880in Al-L and4.048452in Al-P. Finally, thedifferences of the microstress and the lattice constant and the relationship of microstress,defects and extra energy storage were explained.