| The influence of crystallite size on the quality of Rietveld refinement and on the accuracy of quantitative phase determination by Hill-Howard procedure based on Rietveld analysis was tested. The studies were performed on two four-phase powder samples. The content of phases in both powders was the same and equal to 62.5, 12.5, 12.5, and 12.5 wt.% for NiAl, FeAl, Al2O3 and TiC, respectively. The crystallite sizes of all phases are above 100 nm, except for aluminides in sample B for which they are of nanoscale. The crystallite sizes were analyzed by using Williamson-Hall method. The accuracy in content determination of Al2O3 and TiC phases was practically the same for both samples and was equal to 4% for Al2O3 and 6% for TiC. The presence of nanosize aluminides in the sample worsened this accuracy from 2% to 4% for NiAl and from 2% to 10% for FeAl. The powder morphology was analyzed by SEM method. |
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