Contribution to the determination of the entropy production for steady state eutectic growth

1989

A mode of determination of entropy production per unit time for regular eutectic growth is presented. I n order to integrate this thermodynamic quantity, both diffusion equation and coefficient of the interplay between curvature of an interface and concentration field are taken into account. The adaptation of the criterion of minimum entropy production allowed to show the equation (growth law) describing the lamellar structure formation under imposed temperature gradient and given growth rate for an alloy under investigation.

Lamellar eutectic growth at minimum entropy production

1989

Effect of temperature gradient on the lamellar structure formation

1989

The detailed definition of interplay between interface curvature and concentration field is presented. It explains an effect of horizontal component of temperature gradient on the lamellar structure formation during the steady-state eutectic growth. This definition is composed of two competitive terms connected with the heat and matter transfers, respectively. The above competition is interpreted by using the thermodynamics of irreversible processes. Finally, it is shown that the lamellar spacing depends on both the growth rate and temperature gradient for a given regular eutectic solidifying under stationary conditions. The proposed analysis is the fourth part of model developing in "Crystal Research and Technology" which is mentioned in the References.

Minimum undercooling condition as a particular case of the criterion of minimum entropy production

1990

The attempt to compare the diffusional-thermal model based on the criterion of minimum entropy production to diffusional one based on the condition of minimum undercooling has been presented for regular eutectic growth. Finally, the general relationship describing lamellar structure formation is to be reduced to another one proposed by JACKSON and HUNT'S theory. This reduction has been in great part obtained. However, it remain some equivalent terms, which are not identical. It is probably produced by some imperfections of JACKSON and HUNT'S model, as well as any other adversities, e.g., some different assumptions in both compared models. The reduction of the criterion of minimum entropy production to the condition of minimum undercooling has also been suggested.