Solubility of carbon in liquid Al and stability of Al4C3

Abstract

Using thermodynamic models the properties of the Al-C liquid phase have been evaluated from experimental information on the carbon solubility in liquid Al. After slight modification of the description of A14C3 presented by Gluschko and Gurvitch [1], the solubility has been described very well from 950 to 2500 °C with a regular solution model for the liquid phase. Stability of A14C3 was examined through thermodynamic calculations under various conditions. It has been shown that the description of A14C3 can account very well for most thermochemical measurements in a wide temperature range.

Reactions Between Ti2AlC, B4C, and Al and Phase Equilibria at 1000 °C in the Al-Ti-B-C Quaternary System

“…The only binary phase in the Al-C system is Al 4 C 3 . And while this phase has been reported to be stable to above 2100°C, [28] when in contact with TiAl 3 it will react to form TiC and Al at %877°C. [29] The solubility of C in Al is negligible in the temperature range used herein.…”

“…[29] The solubility of C in Al is negligible in the temperature range used herein. [28] 1. [30] At 1000°C, the stable phases are: a-Ti, b-Ti, TiAl 3 , TiAl, TiAl 2 , Ti 2 Al 5 , and TiAl 3 .…”

Conceptual Design for Lower-Energy Primary Aluminum

“…It is determined by the Ranz-Marshall equation given in Eq. [4], in terms of the dimensionless groups Sh, Re, and Sc assembled from the following variables: mass-transfer coefficient k c , chemical diffusion coefficient or interdiffusivity D C-Al , particle diameter d p , together with liquid velocity v, density q, and viscosity l. The Sherwood number Sh = k c D C-Al /d p , the Reynolds number Re = d p vq/l, and the Schmidt number Sc = l/qD C-Al .…”

“…Close to saturation, however, the activity coefficient remains unchanged, with a value of 5.61 at 2185°C, estimated from the Al-C phase diagram given by Qiu and Metselaar. [4] Accordingly, for the present purposes, since ¶ ln c 2 / ¶ ln x 2 fi 0 near carbon saturation, the differential term in Eq. [7] is put equal to unity.…”

“…Downstream from the circulating carbon-saturated Al, the temperature continues to fall toward the region in which carbon saturation is replaced by Al 4 C 3 saturation, a condition that must not be allowed to occur. The relevant part of the phase diagram, according to Qui et al, [4] shows the lower temperature limit as 2160°C. A slightly lower temperature of 2156°C is given by Olden and McClune.…”