@Article{ Knipling-2007-503,
  author = "Knipling, K.E. and Dunand, D.C. and Seidman, D.N.",
  title = "Atom-Probe Tomographic Studies of Precipitation in Al-0.1Zr-0.1Ti (at.\%) Alloys",
  journal = "Microscopy and Microanalysis",
  year= "2007",
  volume = "13",
  number = "6",
  pages = "503--516",
  abstract = "Atom probe tomography was utilized to measure directly the chemical compositions of Al$_3$(Zr$_{1-x}$Ti$_x$) precipitates with a metastable L1$_2$ structure formed in Al-0.1Zr-0.1Ti (at.\%) alloys upon aging at 375$^\circ$C or 425$^\circ$C. The alloys exhibit an inhomogeneous distribution of Al$_3$(Zr$_{1-x}$Ti$_x$) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al$_3$(Zr$_{1-x}$Ti$_x$) precipitates. This is interpreted as being due to the very small diffusivity of Ti in $\alpha$-Al, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al$_3$(Sc$_{1-x}$Ti$_x$/Zr$_x$) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the $\alpha$-Al matrix and Al$_3$(Zr$_{1-x}$Ti$_x$) precipitates and/or a lack of local thermodynamic equilibrium at the interface.",
  doi = "10.1017/S1431927607070882"
}