The microstructure of electrodeposited titanium-aluminum alloys

Academic Article

Abstract

  • The microstructure of electrodeposited titanium-aluminide alloys containing 3.6 to 24.1 at. pct Ti was studied by transmission electron microscopy. The surface morphology of the deposits showed that they contained nodular and faceted grains which tended to be less faceted at higher Ti contents. Extensive 111 twinning was observed in all deposits, and growth striations parallel to were observed in the low Ti deposits. The growth of nodules was linked to the presence of these twins; it was hypothesized that the twin boundaries act as easy atomic attachment points and, therefore, enhance the growth rate. The presence of twins and striations was used to pro-pose a growth mechanism. The 5.3, 15.8, and 24.1 at. pct Ti deposits were single-phase grains of the Ll2 crystal structure, as opposed to the expected equilibrium two-phase mixture of face-centered cubic (fcc) Al (saturated with Ti) and D022 Al3Ti. Calculated electron diffraction in-tensity data were used to demonstrate that the decrease in intensity of the superlattice reflections in the substoichiometric deposits is due to a reduction in the difference in atomic scattering factors between the two lattice site types. © 1992 The Minerals, Metals and Materials Society, and ASM International.
  • Authors

    Digital Object Identifier (doi)

    Author List

  • Janowski GM; Stafford GR
  • Start Page

  • 2715
  • End Page

  • 2723
  • Volume

  • 23
  • Issue

  • 10