Eur. Phys. J. E (2020) 43: 5
https://doi.org/10.1140/epje/i2020-11930-7

Regular Article

Simultaneous melting and solidification of a columnar dendritic microstructure in a temperature gradient: Numerical modeling and experiments^⋆

¹ Shagang School of Iron and Steel, Soochow University, 215137, Suzhou, China
² School of Mechanical Engineering, Southeast University, 211189, Nanjing, China
³ Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, 211189, Nanjing, China
⁴ Otto Schott Institute of Materials Research, Friedrich-Schiller-Universität, Löbdergraben 32, 07743, Jena, Germany

^* e-mail: qingyu.zhang@suda.edu.cn

Received: 25 June 2019
Accepted: 21 January 2020
Published online: 30 January 2020

Abstract

The microstructural evolution of a SCN-ACE alloy in a temperature gradient is studied by cellular automaton (CA) modeling and in situ experiments. The initially columnar dendrites gradually evolve to a completely solid region with a planar solid/liquid interface. The CA simulations and in situ observations present the migration of secondary dendrite arms and liquid pockets due to temperature gradient zone melting (TGZM), and the movement of the interface between a mushy zone and a fully liquid zone. The CA simulations show that the interface movement toward the lower temperature region is caused by the increasing concentration of the fully liquid region. Through updating the concentration in the fully liquid zone to the initial concentration in the CA simulation for mimicking the efficient stirring in liquid, the movement of the interface between the mushy zone and the fully liquid zone is hindered. The simulated liquid fractions and mean concentrations throughout the mushy zone decrease with time, which agree well with the analytical predictions. The simulated concentrations in the resolidified mushy zone are not higher than the temperature-dependent solidus concentrations, implying that no supersaturation remains after the mushy zone fully solidifies.