title: Ultrasonic evaluation of the morphological characteristics of metallic powders in the context of mechanical alloying.
abstract: An ultrasonic method is proposed to characterize the morphological (geometrical) aspects of powders through the elastic modulus dependence of their packing on the factors of polydispersity, coordination number and particle shape. During the mechanical alloying process, the variation in geometrical characteristics of powders provides critical information. Ultrasonic parameters are shown to be sensitive not only to the average contact number per bead (i.e. the coordination number) but also to characteristics of the bead size distribution, when given the same sample preparation and confining pressure. These parameters, in turn, are sensitive to both the granular medium polydispersity and particle shapes. A non-monotonic behavior of the ultrasonic velocity (and of the derived compressional wave modulus) is observed throughout the alloying process, which thus offers possibilities for powder structure monitoring.
authors.affiliation: LUNAM Université, Université du Maine, CNRS UMR 6613, LAUM, Avenue Olivier Messiaen, 72085 LE MANS CEDEX 9, France. Electronic address: laurianne.barguet@univ-lemans.fr.
authors.forename: L
authors.initials: L
authors.lastname: Barguet
authors.affiliation: LUNAM Université, Université du Maine, CNRS UMR 6613, LAUM, Avenue Olivier Messiaen, 72085 LE MANS CEDEX 9, France.
authors.forename: C
authors.initials: C
authors.lastname: Pezerat
authors.affiliation: LUNAM Université, Université du Maine, CNRS UMR 6613, LAUM, Avenue Olivier Messiaen, 72085 LE MANS CEDEX 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Bentahar
authors.affiliation: LUNAM Université, Université du Maine, CNRS UMR 6613, LAUM, Avenue Olivier Messiaen, 72085 LE MANS CEDEX 9, France.
authors.forename: R
authors.initials: R
authors.lastname: El Guerjouma
authors.affiliation: LUNAM Université, Université du Maine, CNRS UMR 6613, LAUM, Avenue Olivier Messiaen, 72085 LE MANS CEDEX 9, France. Electronic address: vincent.tournat@univ-lemans.fr.
authors.forename: V
authors.initials: V
authors.lastname: Tournat
keywords: Effective medium theories; Elastic parameters; Metal powders; Ultrasonic charaterization