Dendrite Fragmentation in Semisolid Casting: Could we Do this Better?


Article Preview

A summary is given of the history of our understanding of dendrite coarsening, including particularly fragmentation. Much is now understood about this process as it takes place in directional solidification of a quiescent melt. Much less is understood about it in the rapidly cooled, turbulent environment of semi-solid casting. The importance of dendrite fragmentation in semi-solid processing is that it is key to obtaining fine final grain size, grain spheroidicity and rapid production rate. I have chosen in this keynote paper to talk about the fundamentals of an important part of the semisolid casting process ... that of “dendrite fragmentation.” The paper is written with an eye to its possible practical usefulness to researchers in process innovation. If we understood the dendrite fragmentation mechanism better, could we achieve finer, more numerous, grains than we do now? Could fully non dendritic structures be obtained industrially in short processing times?



Solid State Phenomena (Volume 285)

Edited by:

Qiang Zhu, Ahmed Rassili, Stephen P. Midson and Xiao Gang Hu




M. C. Flemings, "Dendrite Fragmentation in Semisolid Casting: Could we Do this Better?", Solid State Phenomena, Vol. 285, pp. 3-11, 2019

Online since:

January 2019




* - Corresponding Author

[1] H.D. Brody, M.C. Flemings, Solute redistribution in dendritic solidification, Trans. AIME 236 (1966) 615-624.

[2] T.F. Bower, H.D. Brody, M.C. Flemings, Measurements of solute redistribution in dendritic solidification, Trans. AIME 236 (1966) 624-634.

[3] D.D. Saratovkin, Dendritic Crystallization (translated from Russian by J.E.S. Bradley), Consultants Bureau, New York, (1959).

[4] T.Z. Kattamis, J.M. Coughlin, M.C. Flemings, Influence of coarsening on dendrite arm spacing of aluminum-copper alloys, Trans. AIME 239 (1967) 1504-1511.

[5] A.A. Chernov, Kristallografiya 1 (1956) 583-587.

[6] R. Genders, The interpretation of the macrostructure of cast metals, J. Inst. Metals 35 (1926) 2509-293.

[7] F.C. Langenberg, G. Pestel, C.R. Honeycutt, Grain refinement of steel ingots by solidification a moving electromagnetic field, Trans. Met Soc. AIME 221 (1961) 993-1001.

[8] G. Pestel, F.C. Langenberg, C.R. Honeycutt, Production of fine grained metal castings, U.S. Patent 2,963,758 (1960).

[9] H.P. Utech, M.C. Flemings, Elimination of solute banding in indium antimonide crystals by growth in a magnetic field, J. of Applied Physics (1966) 2021-2024.


[10] H.P. Utech, M. C. Flemings, Process for making solids and products thereof, US Patent 3,464,812 (1969).

[11] D.R. Uhlmann, T. P. Seward III, B. Chalmers, The effect of magnetic fields on the structure of metal alloy castings, Trans. Met. Soc. AIME 236 (1966) 527-531.

[12] T.F. Bower, M.C. Flemings, Formation of the chill zone in ingot solidification, Trans. Met. Soc. AIME 239 (1967) 216-219.

[13] T. Cool, P. W. Voorhees, The Evolution of dendrites during coarsening: fragmentation and morphology, Acta Mater. 127 (2017) 359-367.


[14] R.H. Mathiesen, L. Arnberg, P. Bleuet, A. Somogyi, Crystal fragmentation and columnar-to-equiaxed transitions in Al-Cu studied by synchrotron x-ray video microscopy, Met. and Mat. Trans. 37A (2006) 2515-2524.


[15] G. Zimmermann, C. Pickmann, M. Hamacher, E. Schaberger-Zimmermann, H. Neumann-Heyme, K. Eckert, S. Eckert, Fragmentation-driven grain refinement in directional solidification of AlCu10 wt-% alloy at low pulling speeds. Acta. Mater. 126 (2017) 236-250.


[16] H. Neumann-Heyme, N. Shevchenko, Z. Lei, K. Eckert, O. Keplinger, J. Grenzer, C. Beckermann, S. Eckert, Coarsening evolution of dendritic sidearms: from synchrotron experiments to quantitative modeling, Acta Mater. 146 (2018) 176-186.


[17] J. Zhang, S.O. Poulsen, J.W. Gibbs, P.W. Voorhees, H.F. Poulsen, Determining material parameters using phase field simulations and experiments, Acta Mater. 129 (2017) 220-238.


[18] L. K. Aagesen, A. E. Johnson, J. L. Fife, P. W. Voorhees, M. J. Miksis, S. O. Poulsen, E. M. Lauridsen, F. Marone, M. Stampanoni, Pinch-off of rods by bulk diffusion, Acta Mater. 59 (2011) 4922-4932.


[19] H. Neumann-Heyme, K. Eckert, C. Beckermann, Dendrite fragmentation in alloy solidification due to sidearm pinch-off, Phys. Rev. 92 (2015) 060401.


[20] T. Cool, P.W. Voorhees, Dendrite fragmentation: an experiment-driven simulation, Phil. Trans. A376 (2017), 213.

[21] A.F. Giamei, B. H. Kear, On the nature of freckles in nickel base superalloys, Met. Trans. 1 (1970) 2185-2192.


[22] S.M. Copley, A.F. Giamei, S.M. Johnson, M.F. Hornbecker, The origin of freckles in unidirectionally solidified castings, Met. Trans. 1 (1970) 2193-2204.


[23] R. Mehrabian, M.A. Keane, M.C. Flemings, Experiments on macrosegregation and freckle formation, Met. Trans. 1 (1970) 3238-3241.

[24] J.J. Reeves, T.Z. Kattamis, Model for isothermal dendritic coarsening, Scr. Met. Mater. 5 (1971) 223.

[25] J.P. Gu, C. Beckermann, A.F. Giamei, Motion and remelting of dendrite fragments during directional solidification of a nickel base superalloy, Met. and Mat. Trans. 28A (2006) 1533-1542.


[26] H.J. Diepers, C. Beckermann, I. Steinbach, Simulation of convection and ripening in a binary alloy mush using the phase field method, Acta Mater. 37 (1999) 3663-3678.


[27] A. Hellawell, S. Liu, S.Z. Lu, Dendrite fragmentation and the effects of fluid flow in castings, JOM, March (1997) 18-20.


[28] R. A. Martinez, M. C. Flemings, Evolution of particle morphology in semisolid processing, Met. and Mat. Trans. 36A (2006) 2205-2210.

[29] R.A. Martinez, A. Karma, M.C. Flemings, Spheroidal particle stability in rheocast aluminum alloy, Met. and Mat. Trans. 37A (2006) 2808-2815.