Tales of the Abnormal: Nanocrystalline Grain Growth at Low Temperatures

Employing x-ray diffractometry and electron microscopy, we have investigated thermally induced microstructural evolution in ball-milled nanocrystalline Fe. At low annealing temperatures, the early-stage growth of the area-weighted and volume-weighted average grain sizes deviates strongly from the parabolic behavior expected for normal grain growth. Analysis of the ratio of these two averages indicates that the width of the grain-size...