@Article{ Knipling-2008-114,
  author = "Knipling, K.E. and Dunand, D.C. and Seidman, D.N.",
  title = "Precipitation Evolution in Al-Zr and Al-Zr-Ti alloys during Isothermal Aging at 375--425$^\circ$C",
  journal = "Acta Materialia",
  year= "2008",
  volume = "56",
  number = "1",
  pages = "114--127",
  abstract = "Formation of Al$_3$Zr or Al$_3$(Zr$_{1-x}$Ti$_x$) precipitates with a metastable L1$_2$ structure was investigated in conventionally solidified A1Š0.1 Zr, AlŠ0.2 Zr, AlŠ0.1 ZrŠ0.1 Ti, and AlŠ0.2 ZrŠ0.2 Ti (at.\%) alloys aged isothermally at 375, 400, or 425$^\circ$C. Pronounced hardening results from nanometer-scale, spheroidal Al$_3$Zr or Al$_3$(Zr$_{1-x}$Ti$_x$) (L1$_2$) precipitates within solute-enriched dendrites. Interdendritic regions contain a significantly lower number density of coarser cauliflower-, rod- and plate-shaped precipitates with the L1$_2$ structure. Neither the magnitude of the peak-aged hardness, nor the subsequent loss in hardness due to overaging, is affected by ternary additions of Ti. After extended aging times (1600 h) at 425$^\circ$C, there is no difference in the mean precipitate radii of spheroidal Al$_3$Zr or Al$_3$(Zr$_{1-x}$Ti$_x$) precipitates, confirming that Ti additions do not improve the coarsening resistance. Comparison with prior coarsening studies on Al$_3$Zr, and Al$_3$Zr or Al$_3$(Zr$_{1-x}$V$_x$), Al$_3$Zr or Al$_3$(Zr$_{1-x}$Ti$_x$) and Al$_3$Zr or Al$_3$(Zr$_{1-x-y}$V$_x$Ti$_y$) (L1$_2$) precipitates at 425$^\circ$C confirms the lack of an effect from ternary alloying additions.",
  doi = "10.1016/j.actamat.2007.09.004"
}