Containerless undercooling and solidification in drop tubes

Correlations between Surface and Interface Energies with Respect to Crystal Nucleation

“…Measuring the duration of radiant cooling from release to nucleation event, T n may be first calculated via a numerical integration of the cooling rate which takes into account linear evolutions of liquid density (29), heat capacity (72), and hemispherical emissivity. Considering only data at the melting temperature leads to overestimation of T , as made on Nb by Lacy et al (73) in their pioneer work in this field (i.e., 530 K instead of 450 K). Moreover, the initial temperature can be identified with T m only for indisputably gas-free specimens.…”

Cooling and solidification of liquid-metal drops in a gaseous atmosphere

“…A more detailed discussion, including justification for the various approximations, has been published previously [6]. The differential equations of motion for the drop arc dx/dt = U (1) dU/dt = gAp/pp -3CapU2/49pd (2) 0022-2461/92 $03..00 + . 12 9 1992 Chapman & Hall where g is the gravitational field strength, p is the density of the gas, Pp is the density of the drop, Ap = Op -P, Ca is the coefficient of drag, d is the drop diameter, U is the drop speed, x is the distance fallen, and t is time.…”

“…The usefulness of drop tubes for studies of containerless liquid-metal supercooling is well established [1][2][3][4]. The typical experiment involves a small (several millimetres in diameter) drop falling from a levitated position within an evacuated or helium-filled drop tube chamber.…”

“…Modelling studies of liquid-drop kinematics during the several second fall period, as well as of related processes, such as internal circulation and heat transfer, must be carried out to both guide and interpret corresponding experimental studies, Accordingly, several such studies have been reported [1,2,5].…”

Computation of continuous cooling transformation diagrams for the heterogeneous nucleation in Sn-5 mass pct Pb droplets

“…Experimental techniques that have been developed to study droplet supercooling include hot-stage droplet dispersion techniques developed by Turnbull and co-workers, [6,7,8] droplet emulsification methods explored by Turnbull [9] and developed by Perepezko and co-workers, [10,11,12] MacIsaac et al [13] levitation melting techniques, [14,15,16] and drop tower methods. [17,18] However, most of these techniques only apply to stationary droplets, with the exception of drop tower techniques, and as such only generate knowledge specific to the droplets generated by a specific technique. While such knowledge is of scientific importance, it cannot be immediately extended to predict the droplet supercooling and solidification in industrial processes, such as gas atomization, centrifugal atomization, spray forming, and thermal spraying, in which droplets in various sizes solidify while traveling in a gas.…”