title: TEM analysis of tweed structure in high-palladium dental alloys.
abstract: Transmission electron microscopy and convergent-beam electron diffraction were used to study three high-palladium dental alloys: an as-cast Pd-Ga alloy, a cast Pd-Cu-Ga alloy aged at room temperature for over 5 years, and a cast Pd-Cu-Ga alloy annealed at 1023 K for 2 h and slowly cooled to room temperature. Bands containing a tweed structure in the Pd-Ga alloy were 120degrees twins with (1 1 0 mirror planes. Within these bands the alloy had a face-centered tetragonal structure with a c/a ratio of 1.03. The aged Pd-Cu-Ga alloy contained a larger amount of tweed structure than the original as-cast alloy, along with randomly oriented bands and thin lath-like regions. The annealed Pd-Cu-Ga alloy contained rectangular particles of a secondary phase that may be Pd2Ga, Pd5Ga2 or Pd13Ga5. The microtwinned band structure relieves the strain energy arising from transformation of the f.c.c. palladium solid solution on cooling.
authors.affiliation: Ohio State University, Columbus, OH 43210, USA.
authors.forename: S V
authors.initials: SV
authors.lastname: Nitta
authors.forename: W A
authors.initials: WA
authors.lastname: Clark
authors.forename: W A
authors.initials: WA
authors.lastname: Brantley
authors.forename: R J
authors.initials: RJ
authors.lastname: Grylls
authors.forename: Z
authors.initials: Z
authors.lastname: Cai