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P.A. Nikrityuk, K. Eckert, R. Grundmann Institute for Aerospace Engineering,

SFB 609. NUMERICAL STUDY OF THE INFLUENCE OF AN APPLIED ELECTRICAL POTENTIAL ON THE SOLIDIIFCATION OF A BINARY METAL ALLOY. P.A. Nikrityuk, K. Eckert, R. Grundmann Institute for Aerospace Engineering, Dresden University of Technology, Germany.

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P.A. Nikrityuk, K. Eckert, R. Grundmann Institute for Aerospace Engineering,

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  1. SFB 609 NUMERICAL STUDY OF THE INFLUENCE OF AN APPLIED ELECTRICAL POTENTIAL ON THE SOLIDIIFCATION OF A BINARY METAL ALLOY P.A. Nikrityuk, K. Eckert, R. Grundmann Institute for Aerospace Engineering, Dresden University of Technology, Germany 2nd Sino-German Workshop on Electromagnetic Processing of Materials October 16-19, 2005, Dresden, Germany

  2. SFB 609 Historical preamble of a pulse electric discharging (PED) in metallurgy • The goal of PED is the modification of the microstructure during solidification • A. Mirsa (Metal. Trans. A, 1985, 1986) - Pioneering publication about en experimental study of DC passing though the solidified melt. Grain size refinement was reported. • M. Nakada et al (ISIJ Int., 1990) - Detailed experimental study of the PED impact on Sn15wt%Pb alloy solidification. Hypothesis: theLorentz force (Pinch force) is responsible for the grain refinement through mechanical shearing of dendrites. • A. Prodhan et al (Met. Mat. Trans.B, 2001) – Experimental study of solidification of Aluminum in electric field. The reduction of pinhole porosity and columnar-to-equiaxed transition was reported by application DC and 50 Hz AC. • M. Gao et al (Mat. Sci Eng. A, 2002) – Experimental study of the ZA27 alloy solidification treated with PED. Modification of the dendrite grain size from larges to the smaller was reported.

  3. SFB 609 Historical preamble of a pulse electric discharging (PED) in metallurgy • The goal of PED is the modification of the microstructure during solidification • A. Mirsa (Metal. Trans. A, 1985, 1986) - Pioneering publication about en experimental study of DC passing though the solidified melt. Grain size refinement was reported. • M. Nakada et al (ISIJ Int., 1990) - Detailed experimental study of the PED impact on Sn15wt%Pb alloy solidification. Hypothesis: theLorentz force (Pinch force) is responsible for the grain refinement through mechanical shearing of dendrites. • A. Prodhan et al (Met. Mat. Trans.B, 2001) – Experimental study of solidification of Aluminum in electric field. The reduction of pinhole porosity and columnar-to-equiaxed transition was reported by application DC and 50 Hz AC. • M. Gao et al (Mat. Sci Eng. A, 2002) – Experimental study of the ZA27 alloy solidification treated with PED. Modification of the dendrite grain size from larges to the smaller was reported.

  4. SFB 609 Historical preamble of a pulse electric discharging (PED) in metallurgy • The goal of PED is the modification of the microstructure during solidification • A. Mirsa (Metal. Trans. A, 1985, 1986) - Pioneering publication about en experimental study of DC passing though the solidified melt. Grain size refinement was reported. • M. Nakada et al (ISIJ Int., 1990) - Detailed experimental study of the PED impact on Sn15wt%Pb alloy solidification. Hypothesis: theLorentz force (Pinch force) is responsible for the grain refinement through mechanical shearing of dendrites. • A. Prodhan et al (Met. Mat. Trans.B, 2001) – Experimental study of solidification of Aluminum in electric field. The reduction of pinhole porosity and columnar-to-equiaxed transition was reported by application DC and 50 Hz AC. • M. Gao et al (Mat. Sci Eng. A, 2002) – Experimental study of the ZA27 alloy solidification treated with PED. Modification of the dendrite grain size from larges to the smaller was reported.

  5. SFB 609 Problem formulation macroscale electric current density is homogeneous microscale mesoscale R0=25 mm, H0=75 mm

  6. SFB 609 Problem formulation macroscale electric current density is homogeneous microscale mesoscale micro- and mesoscale electric current density is NOT homogeneous R0=25 mm, H0=75 mm

  7. SFB 609 Macro-energy transport during Sn15wt%Pb solidification by DC application Steady DC from 50 s to 80 s during UDS

  8. SFB 609 Macro-energy transport during Sn15wt%Pb solidification by DC application Steady DC from 50 s to 80 s during UDS Periodic DC with period “on and off ” 1 sec Joule heating is reduced !!!!!

  9. SFB 609 DC is switch on after30 sec and switched off after 60 sec Volume fraction of the liquid Temperature 0.1V, 4672 A

  10. SFB 609 Joule heating effect Joule heating in the liquid phase >> Joule heating in the solid phase

  11. SFB 609 Axial profiles of the temperature and the electric potential at t = 70 sec solid liquid

  12. SFB 609 Axial profiles of the temperature and the electric potential at t = 70 sec solid liquid Analytic model – Nikrityuk et al, 2005, Wiley-VCH Verlag

  13. SFB 609 Mesoscale consideration Rd=10-4 m Vs=10-4 m/s E=1-30 V/m Electroconducting non-homogeneous media, Nikrityuk et al, Met. Mat. Trans, 2005, submitted

  14. SFB 609 Spatial distribution of electric potential, current density and Joule heating electric potential current density Joule heating

  15. SFB 609 Spatial distribution of the velocity field

  16. SFB 609 Spin-up of the interdendritic liquid Nikrityuk et al, Phys Fluids, 2005 Time scale of spin-up is 10-3 sec !!!!

  17. SFB 609 Conclusions • Application of PED perpendicularly to the solidification front lead to a much stronger heating of the liquid phase in comparison to the solid phase (the heating is caused by the Joule heating effect) • A shorter duration of PED decrease of the Joule heating of the melt • The inhomogeneity of the electrical current in the mushy zone induces a Lorentz force (pinch force), which induces a toroidal vortex near the dendrite tip. This convection may lead to the accumulation of solute at the dendrite tip and obstruction of the columnar grain growth (Martorano et al, 2003, Willers et al 2005, Eckert et al 2005) • The spin-up time of the vortex has order of O(10-3) sec for Ez of order O(10) V/m Models proposed to use • Macroscale level: a variant of the mixture model (Stefanescu, 1996) • Microscale level: Phase-field model (Karma 1996, Beckermann, 1999)

  18. SFB 609 Cited publications • P.A. Nikrityuk, M. Ungarish, K. Eckert, R. Grundmann. “Spin-up of a liquid metal flow driven by a rotating magnetic field in a finite cylinder. A numerical and analytical study“ Phys. Fluids 17, 2005, 067101-1-016 • P.A. Nikrityuk, K. Eckert, R. Grundmann. “Numerical study of the influence of a rotating magnetic field on unidirectional solidification of a binary metal alloy”, I.J.Heat and Mass Transfer, in press, 2005 • P.A. Nikrityuk, K. Eckert, R. Grundmann. “Rotating magnetic field driven flows in conducting inhomogeneous media. Part I: Numerical Study“, submitted to Metallurgical and Materials Transactions B, 2005 • P. A. Nikrityuk, K. Eckert, R. Grundmann. Proceeding of Continuous Casting Conf., Wiley-VCH Verlag, pp. 1-14, 2005. • S. Eckert, B. Willers, P. Nikrityuk, K. Eckert, U. Michel, G. Zouhar. Application of a rotating magnetic field during directional solidification of Pb-Sn alloys: Consequences on the CET. Mat. Sci. Eng. A, in press, 2005. Proposed partners from China • Dr. YANG “Microstructure evolution of semi-solid magnesium alloy AZ91D under electric current” • Dr. PAN “Impose of electric field on crystallization of metallic amorphous”

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