Directional solidification of Al–1.5wt% Ni alloys under diffusion transport in space and fluid-flow localisation on earth

Analysis by synchrotron X-ray radiography of convection effects on the dynamic evolution of the solid–liquid interface and on solute distribution during the initial transient of solidification

“…This effect is even more visible at low growth rates. In particular, a large macroscopic deformation of the solidification front and associated radial nonuniformity of the microstructure have already been observed during Al-Ni solidification [25], even for relatively thin samples (thickness $200 lm), as in our case [26]. A mechanism of deformation of the front was earlier suggested by Hunt [27].…”

Solidification microstructures and solid-state parallels: Recent developments, future directions

“…Numerous experimental studies have been performed where the flow is induced by thermal and/or solutal buoyancy forces [255][256][257][258][259][260][261][262][263]. While these experimental investigations reveal several interesting phenomena, few general statements regarding the convection effect can be made.…”

“…Forced convection, as in DC casting of aluminum alloys, can affect the formation of feathery grains made of twinned dendrites [280]. Finally, the dendritic microstructure can also be altered by convection that is induced by vibrations, and dendrite fragmentation can result [260,281].…”

In-Situ and Real-Time Investigation of Columnar-to-Equiaxed Transition in Metallic Alloy

“…Indeed, it is well known on bulk samples that, even when solidification is performed in both thermal and solutal stabilizing configuration, strong convective fluid flow can develop under the effect of horizontal temperature gradient. This leads to a severe distortion of the front (steepling and clustering phenomena [14,15] ). These phenomena are also observed in our experiments, even if the width of the present samples is comparatively small.…”

“…This suggests that convection effects are no longer disturbing for equiaxed growth regimes because of the high pulling rate, which is in agreement with previous studies. [14,15] The four pictures in Figure 4 are taken at the same level in different solidification runs on the same sample, so that a direct comparison of the microstructures is possible. The location (and thus the temperature) of the effective front, indicated by a dashed line, increases with the growth velocity (Figures 4(a) through (d)), which means that the length of the undercooled region decreases as a function of the growth velocity.…”