LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

CREATE AN ACCOUNT

Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Castle, EG; Mullis, AM; Cochrane, RF (2014)
Publisher: Elsevier
Languages: English
Types: Article
Subjects:
A melt encasement (fluxing) technique has been used to systematically study the microstructural development and velocity-undercooling relationship of a Cu-8.9 wt%Ni alloy at undercoolings up to 235 K. A complex series of microstructural transitions have been identified with increasing undercooling. At the lowest undercoolings a 〈1 0 0〉 type dendritic structure gives way to an equiaxed grain structure, consistent with the low undercooling region of grain refinement observed in many alloys. At intermediate undercoolings, dendritic growth returns, consisting of dendrites of mixed 〈1 0 0〉 and 〈1 1 1〉 character. Within this region, 8-fold growth is first observed at low undercoolings, indicating the dominance of 〈1 0 0〉 character. As undercooling is increased, 〈1 1 1〉 character begins to dominate and a switch to 6-fold growth is observed. It is believed that this is an extended transition region between 〈1 0 0〉 and 〈1 1 1〉 dendrite growth, the competing anisotropies of which are giving rise to a novel form of dendritic seaweed, characterised by its containment within a diverging split primary dendrite branch. At higher undercoolings it is suggested that a transition to fully 〈1 1 1〉 oriented dendritic growth occurs, accompanied by a rapid increase in growth velocity with further increases in undercooling. At the highest undercooling achieved, a microstructure of both small equiaxed grains, and large elongated grains with dendritic seaweed substructure, is observed. It is thought that this may be an intermediate structure in the spontaneous grain refinement process, in which case the growth of dendritic seaweed appears to play some part.
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • [1] J.L. Walker, The physical chemistry of process metallurgy, part 2, in: G.R. St. Pierre (Ed.), Interscience, New York, 1959, pp. p.845.
    • [2] A.F. Norman, K. Eckler, A. Zambon, F. Gärtner, S.A. Moir, E. Ramous, D.M. Herlach, A.L. Greer, Application of microstructure-selection maps to droplet solidification: a case study of the Ni-Cu system, Acta Materialia, 46 (1998) 3355-3370.
    • [3] K.F. Kobayashi, P.H. Shingu, The solidification process of highly undercooled bulk Cu-O melts, Journal of Materials Science, 23 (1988) 2157-2166.
    • [4] S.E. Battersby, R.F. Cochrane, A.M. Mullis, Highly undercooled germanium: Growth velocity measurements and micro structural analysis, Materials Science and Engineering A, 226-228 (1997) 443-447.
    • [5] N. Liu, G. Yang, F. Liu, Y. Chen, C. Yang, Y. Lu, D. Chen, Y. Zhou, Grain refinement and grain coarsening of undercooled Fe-Co alloy, Materials Characterization, 57 (2006) 115-120.
    • [6] K.A. Jackson, J.D. Hunt, D.R. Uhlmann, T.P. Seward, Lamellar and Rod Eutectic Growth, Trans. TMS-AIME, 236 (1966) 149-158.
    • [7] T.Z. Kattamis, M.C. Flemings, Mod. Casting, 52 (1967).
    • [8] R.J. Schaefer, M.E. Glicksman, Direct observation of dendrite remelting in metal alloys, Trans. AIME, 239 (1967) 257.
    • [9] M. Schwarz, A. Karma, K. Eckler, D.M. Herlach, Physical Mechanism of Grain Refinement in Solidification of Undercooled Melts, Physical Review Letters, 73 (1994) 1380.
    • [10] A. Karma, W.-J. Rappel, Quantitative phase-field modeling of dendritic growth in two and three dimensions, Physical Review E, 57 (1998) 4323.
    • [11] A.M. Mullis, R.F. Cochrane, On the Karma Model for Spontaneous Grain Refinement at High Solid Fractions, International Journal of Non-Equilibrium Processing, 11 (2000) 283-297.
    • [12] A.M. Mullis, Dendritic seaweed growth and the relationship to spontaneous grain refinement, in, 2007, pp. 19-28.
    • [13] Y. Sawada, Transition of growth form from dendrite to aggregate, Physica A: Statistical Mechanics and its Applications, 140 (1986) 134-141.
    • [14] K.I. Dragnevski, R.F. Cochrane, A.M. Mullis, The solidification of undercooled melts via twinned dendritic growth, Metallurgical and Materials Transactions A, 35 (2004) 3211-3220.
    • [15] S.E. Battersby, R.F. Cochrane, A.M. Mullis, Growth velocity-undercooling relationships and microstructural evolution in undercooled Ge and dilute Ge-Fe alloys, Journal of Materials Science, 34 (1999) 2049-2056.
    • [16] J.A. Dantzig, P. Di Napoli, J. Friedli, M. Rappaz, Dendritic Growth Morphologies in Al-Zn Alloys. Part II: Phase-field Computations (preprint), Metallurgical and Materials Transactions A, Submitted (2013).
  • No related research data.
  • No similar publications.

Share - Bookmark

Cite this article