Abstract
Extensive SEM work was carried out on deep-etched specimens to reveal the evolution of compacted and chunky graphite in magnesium-modified multicomponent Fe-C-Si alloys during early solidification and at room temperature. The findings of this research were then integrated in the current body of knowledge to produce an understanding of the crystallization of compacted and chunky graphite. It was confirmed that growth from the liquid for both compacted and chunky graphite occurs radially from a nucleus, as foliated crystals and dendrites. The basic building blocks of the graphite aggregates are hexagonal faceted graphite platelets with nanometer height and micrometer width. Thickening of the platelets occurs through growth of additional graphene layers nucleated at the ledges of the graphite prism. Additional thickening resulting in complete joining of the platelets may occur from the recrystallization of the amorphous carbon that has diffused from the liquid through the austenite, once the graphite aggregate is enveloped in austenite. With increasing magnesium levels, the foliated graphite platelets progressively aggregate along the c-axis forming clusters. The clusters that have random orientation, eventually produce blocky graphite, as the spaces between the parallel platelets disappear. This is typical for compacted graphite irons and tadpole graphite. The chunky graphite aggregates investigated are conical sectors of graphite platelets stacked along the c-axis. The foliated dendrites that originally develop radially from a common nucleus may aggregate along the c-axis forming blocky graphite that sometimes exhibits helical growth. The large number of defects (cavities) observed in all graphite aggregates supports the mechanism of graphite growth as foliated crystals and dendrites.
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1 G.F. Geier, W. Bauer, B.J. McKay, P. Schumacher, Microstructure transition from lamellar to compacted graphite using different modification agents, Mat. Sci. Eng. A 413-414 (2005) 339-345.
D.K. Bandyopadhyay, D.M. Stefanescu, I. Minkoff and S.K. Biswal: Physical Metallurgy of Cast Iron IV, Tokyo, Mat. Res. Soc. Proc., G. Ohira, T. Kusakawa and E. Niyama, eds., Pittsburgh, 1989, p. 27.
3 H. Itofuji, H. Uchikawa, Formation Mechanism of Chunky Graphite in Heavy-section Ductile Cast Irons, Trans. AFS 98 (1990) 429-448.
G. Alonso, D.M. Stefanescu, P. Larrañaga, and R. Suarez: Int. J. Cast Metals Res., 2016, DOI:10.1179/1743133615Y.0000000020.
5 D.M. Stefanescu, G. Alonso, P. Larrañaga, R. Suarez, On the stable eutectic solidification of Iron-Carbon-Silicon alloys, Acta mater. 103 (2016) 103-114.
D.M. Stefanescu L. Dinescu, S. Craciun, M. Popescu, in Proc. 46th Int. Foundry Congress, CIATF Madrid, Spain, 1979, paper 37-1.
7 A. Velichko, C. Holzapfel, F. Mücklich, 3D Characterization of Graphite Morphologies in Cast Iron, Adv. Eng. Mater. 9(1-2) (2007) 39.
8 D.M. Stefanescu, F. Martinez, I.G. Chen, Solidification Behavior of Hypoeutectic and Eutectic Compacted Graphite Cast Irons, Chilling Tendency and Eutectic Cells, AFS Trans. 91 (1983) 205-216
9 X.J. Deng, P.Y. Zhu, Q.F. Liu, Structure and Formation of Vermicular Graphite, AFS Trans. 94 (1986) 927-34
10 S. I. Karsay, E. Compomanes, Control of Graphite Structure in Heavy Ductile Iron Casting, AFS Trans. 92(1970) 85-92.
11 P.C. Liu, C.L. Li, D.H. Wu, C.R. Loper, SEM study of chunky graphite in heavy section ductile iron, AFS Trans. 91 (1983). 119-126.
12 A.N. Roviglione, J.D. Hermida, From flake to nodular: a new theory of morphological modification in gray cast iron, Metall. Mater. Trans. 35B (2004) 313.
13 D.M. Stefanescu, G. Alonso, P. Larrañaga, E. De la Fuente, R. Suarez, On the crystallization of graphite from liquid iron-carbon-silicon melts, Acta Mater. 107 (2016) 102-126
14 D.D. Saratovkin, Dendritic Crystallization, Consultants Bureau, New York, NY, 1959
15 J. Sertucha, J. Lacaze, S. Armendariz, P. Larrañaga, Statistical analysis of the influence of some trace elements on chunky graphite formation in heavy section nodular iron castings, Metall. Mater. Trans. A 44(3) (2013) 1159-1162 DOI 10.1007/s11661-012-1592-8
16 H. Itofuji, A. Masutani, Nucleation and growth behavior of chunky graphite, Int. J. Cast Metals Res. 14 (2001) 1-14.
D.D. Double, and A. Hellawell: The Metallurgy of Cast Iron, B. Lux, I. Minkoff, and F. Mollard, eds., Georgi Publishing Co., St Saphorin, 1975, pp. 509–28.
18 S.H. Yoon, S. Lim, S.H. Hong, W. Qiao, D.D. Whitehurst, I. Mochida et al., A conceptual model for the structure of catalytically grown carbon nano-fibers, Carbon 43 (2005) 1828-1838.
19 D.D. Double, A. Hellawell, The nucleation and growth of graphite-the modification of cast iron, Acta Metall. Mater. 43 (1995) 2435-42.
20 D.D. Double, A. Hellawell, The structure of flake graphite in Ni-C eutectic alloy, Acta Metall. 17 (1969) 1071- 83.
21 D.H. St. John, L.M. Hogan, Metallography and growth crystallography of Al3Ti in Al-Ti alloys up to 5 wt% Ti, J. Crystal Growth 46 (1979) 387-98
22 M.C. Flemings, Solidification Processing, McGraw Hill Series in Materials Science and Engineering, McGraw Hill, New York, NY, 1974.
W. Bollman, and B. Lux B: The Metallurgy of Cast Iron, B. Lux, I. Minkoff, F. Mollard, eds., Georgi Publishing, St. Saphorin, 1975, pp. 462–70.
E. Moumeni, N.S. Tiedje, A. Horsewell, J.H Hattel: A TEM Study on the Microstructure of Fine Flaky Graphite, 52nd International Foundry Conference, Portoroz, Slovenia, 2012
25 H.M. Muhmond, H. Fredriksson, Relationship between the Trace Elements and Graphite Growth Morphologies in Cast Iron, Metall. Mater. Trans. 45A (2014) 6187-99
26 K. Theuwissen, J. Lacaze, L. Laffont, Structure of graphite precipitates in cast iron, Carbon (2015) DOI:10.1016/j.carbon.2015.10.066.
27 S. Amini, R. Abbaschian, Nucleation and growth kinetics of graphene layers from a molten phase Carbon 51 (2013) 110-123.
K.M. Fang, G.C. Wang, X. Wang, L. Huang, and G.D. Deng: in Science and Processing of Cast Iron VIII, Y.X. Li, H.F. Shen, Q.G. Xu, Z.Q. Han, eds., Tsinghua Univ. Press, Beijing, 2006, pp. 181–87.
I. Minkoff, I. Einbinder, Official Exchange Paper—Israel, International Foundry Congress, 1963, pp 139–43
I. Minkoff: in The Physical Metallurgy of Cast Iron, Stockholm, Mat. Res. Soc. Symposia Proc., H. Fredriksson, and M. Hillert, eds., North-Holland, 1985, pp. 37–45.
31 M. Hamasumi, A newly observed pattern of imperfect graphite spherulite in nodular iron, Trans. JIM, 6 (1965) 234-239.
G.R. Purdy, and M. Audier: in The Physical Metallurgy of Cast Iron, Stockholm, H. Fredriksson and M. Hillert, eds., Mat. Res. Soc. Symposia Proc., North-Holland, 1985, pp. 13-23.
33 D. Ugarte, Nature, London 359 (1992) 707
J.P. Sadocha, and J.E. Gruzleski: in The Metallurgy of Cast Iron, B. Lux, I. Minkoff, and F. Mollard, eds., Georgi Publishing Co., St Saphorin, 1975, pp. 443-59
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The authors wish to acknowledge Caterpillar and Fundiciones Garbi for supplying some of the analyzed samples. Thermal Quality Control Technologies, S.L.U. is also gratefully acknowledged for sharing its facilities for samples acquisition.
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Manuscript submitted January 27, 2016.
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Stefanescu, D.M., Huff, R., Alonso, G. et al. On the Crystallization of Compacted and Chunky Graphite from Liquid Multicomponent Iron-Carbon-Silicon-Based Melts. Metall Mater Trans A 47, 4012–4023 (2016). https://doi.org/10.1007/s11661-016-3541-4
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DOI: https://doi.org/10.1007/s11661-016-3541-4