Analysis of ball-milled Mo powder using X-ray diffraction

Abstract

X-ray diffraction measurements and analysis were carried out on ball-milled Mo powder. During the ball milling of Mo powder, several stages of deformation could be identified. After short durations of ball milling, still undeformed starting powder was present and the volume fraction of this was determined. The initial aggregates of deformed powder particles exhibited a deformation texture. On prolonged ball milling, the particle size decreased, the deformation texture disappeared and internal strains built up. By simulation and matching of the corresponding line profiles using a Monte Carlo type of line-profile simulation based on a simple three-dimensional model of the distribution of straight dislocations, an estimate of the dislocation density in the ball-milled particles was obtained.

Acknowledgements

This work has been part of the research programme of the Stichting voon Fundamentele Onderzoek der Materie, The Netherlands. Financial support was also provided by the Stichting voon de Technesche Weterschappen. Part of this work was carried out under project number MS.97007 in the framework of the strategic research programme of the Netherlands Institute for Metals Research in The Netherlands (www.nimr.nl). The authors are indebted to Dr H. Bakker for providing the ball-milling facilities, to Dr G. Rixecker for performing the ball-milling experiments and to E.J.M. Fakkeldij for operating the scanning electron microscope.

Notes

† Using and , with , recognizing that equals the integrated intensity, and that the integrated intensity (per unit volume) is independent of the state of deformation.

† The result of series A _m after ball milling for 0.5 h has not been shown because the broadening did not comply with the assumed type of size–strain separation; that is, a negative part cut from the ordinate occurred in the plot of β_tot versus 1/d ^HKL .