The impact of turbulent flow on the solidification of metal alloys driven by a rotating magnetic field


The impact of turbulent flow on the solidification of metal alloys driven by a rotating magnetic field

Nikrityuk, P. A.; Eckert, K.; Eckert, S.

The paper presents a study concerning the impact of a turbulent, rotating melt flow on the macrosegregation and the shape of the mushy zone during unidirectional solidification of an Al-7wt%Si alloy. The flow is generated by applying a rotating magnetic field (RMF). Direct numerical simulations (DNS) were performed to study the weakly turbulent flow. The transient heat and mass transfer were simulated using a standard mixture model (Bennon and Incropera, 1987). The treatment of the fluid flow in the mushy zone requires the use of permeability and mixture viscosity models, which also allow for consideration of both columnar and equiaxed solidification. Our results demonstrate that in the case of columnar solidification the Ekman pumping effect causes the development of a Si-enriched liquid channel along the rotational axis . The Taylor-Goertler vortices, which appear randomly along the side wall of the cylinder, amplify the solute transport from the wall to the axis intermittently in the upper part of the mushy zone. This effect leads to a wavy shape of the mushy zone and segregation in the form of a fir tree with a distinct accumulation of silicon along the axis of the cylinder. Moreover, we propose strategies to avoid macrosegregation by using a pulse-modulated rotating magnetic field.

Keywords: solidification; rotating magnetic field; turbulent flow; macrosegregation

  • Lecture (Conference)
    2nd International Conference on Advances in Solidification Processes, 17.-22.06.2008, Leoben, Austria
  • International Journal of Cast Metals Research 22(2009)No 1-4, 236-239

Permalink: https://www.hzdr.de/publications/Publ-11205
Publ.-Id: 11205