Iron-molybdenum powders ground in a planetary ball mill under different operating conditions were studied by x-ray diffraction line profile analysis using a recently developed whole powder pattern modeling approach. The evolution of the microstructure, expressed in terms of size distribution of coherent scattering domains, average dislocation density, and edge/screw character, shows the importance of the main process parameters: the ratio between jar and main disk rotation speeds, and ball milling time. A characteristic three-stage process is observed, with work hardening followed by particle flattening/bending before nanocrystalline grains form by a fragmentation process triggered by localized deformation. The relationship between lattice defect density and domain size suggests a progressive transition between statistically stored to geometrically necessary dislocations, with the latter mostly present as excess dislocations at the nanodomain boundary.
|Titolo:||High-energy grinding of FeMo powders|
|Autori:||D'Incau, Mirco; Leoni, Matteo; Scardi, Paolo|
|Titolo del periodico:||JOURNAL OF MATERIALS RESEARCH|
|Anno di pubblicazione:||2007|
|Numero e parte del fascicolo:||6|
|Digital Object Identifier (DOI):||10.1557/JMR.2007.0224|
|Appare nelle tipologie:||03.1 Articolo su rivista (Journal article)|