The effect of solidification variables on tertiary dendrite arm spacing in unsteady-state directional solidification of Sn–Pb and Al–Cu alloys

Thermosolutal convective effects on dendritic array spacings in downward transient directional solidification of Al–Si alloys

“…A similar observation has been reported recently concerning primary dendritic spacings of Al-Cu alloys in steady-state [13] and unsteadystate solidification [19], and of Al-Si alloys in unsteady-state solidification [20]. In addition, by examining the experimental results of tertiary spacings obtained by Sá et al [6] for unsteady-state vertical upward solidification conditions, it can be seen that λ 3 was also found to be independent of composition for hypoeutectic Al-Cu alloys.…”

“…Secondary and tertiary dendrite arm spacings (λ 2 and λ 3 ) were measured by averaging the distance between adjacent side branches on the longitudinal and transversal sections, respectively. [19,6]. In these methods, 40 λ 1 , λ 2 and λ 3 values were measured for each selected position.…”

“…where Sá et al [6] have reported recently that a −0.55 power law characterizes the experimental variation of tertiary spacing with cooling rate along the unsteady-state solidification of Sn-Pb and Al-Cu alloys, and can be expressed as: …”

“…Grugel [5] has carried out experiments in directional steady-state growth of Al-Si alloys and from the spacing measurements proposed a growth law relating tertiary arm spacing (λ 3 ) with the local solidification time. Sá et al [6] in a recent article have shown that a −0.55 law characterizes the tertiary spacing variation with the cooling rate for hypoeutectic Sn-Pb and Al-Cu alloys solidified under transient heat flow conditions. Much research has been devoted to the definition of the factors affecting the fineness of the dendritic structure.…”

The correlation between dendritic microstructure and mechanical properties of directionally solidified hypoeutectic Al-Ni alloys

“…The model has been validated in previous articles [13][14][15][18][19][20] against experimental results concerning the solidification of Al-Cu, Zn-Al, Al-Si and SnPb alloys. The tip growth rate is given by [14,15]: (1) where α SL is mushy zone thermal diffusivity, φ 1 and φ 2 are solidification constants associated with the displacement of solidus and liquidus isotherms, k S is the solid thermal conductivity, T Liq is the liquidus temperature, T Sol is the nonequilibrium solidus temperature, T 0 is the environment temperature, n is the square root of the ratio of thermal diffusivities of solid metal and mushy zone, M is the ratio of heat diffusivities of the solid metal and the mold material, h i is the metal/mold heat transfer coefficient and S L is the position of liquidus isotherm from the metal/mold interface.…”