Influence of Silicon on Nucleation and Growth Process of Spherical Graphite in Ni-C Alloys Solidification Structure

Abstract:

Plasma etching, SEM and quantitative metallographic analysis technology were used to study the influence of Si on nucleation and growth process of spherical graphite in Ni-C alloys solidification microstructure. Pure Si, Ni-Si alloys and Fe-Si alloys were added into Ni-C melts respectively, and the solid microstructures were compared. The density, diameter size and roundness of spherical graphite were studied in this work to reveal the influence of Si on the morphology of graphite. The Ni-C alloy was etched by plasma etch, and the morphologies and composition of graphite nucleus were observed by scanning electron microscope (SEM) and electron energy spectrum analysis (EDS). The results suggested that the high Si melt zone in melt strongly promoted the enrichment and carbide of graphite, which both promoted the nucleation and growth of graphite. The change in Si content had a large effect on the roundness of the graphite, the higher the Si content, the better the roundness of the graphite.

• Periodical: Materials Science Forum (Volume 913)
• Pages: 220-226
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.913.220
• Online since: February 2018
• Authors: Di Meng, Xue Tao Wang, Hong Liang Zheng*, Xue Lei Tian
• Keywords: Graphite Growth, Graphite Nucleus, Microstructure, Ni-C Alloy, Si

References

[1] S I. Karsay, Spheroidal graphite iron II engineering design properties application, Quebec iron and titanium corporation, Canada, (1971).

[2] A R. Ghaderi, M Nili Ahmadabadi and H M Ghasemi, Effect of graphite morphologies on the tribological behavior of austempered cast iron, Wear. 255 (2003) 410-416.

DOI: 10.1016/s0043-1648(03)00156-x

[3] Z R He, G X Lin and S Ji, Deformation and fracture of cast iron with an optimized microstructure, Mater. Charact. 389 (1997) 251-258.

DOI: 10.1016/s1044-5803(97)00080-6

[4] K Qi, F Yu, F Bai, Z Yan, Z Wang and T Li, Research on the hot deformation behavior and graphite morphology of spheroidal graphite cast iron at high strain rate, Mater. Des. 30 (2009) 4511-4515.

DOI: 10.1016/j.matdes.2009.05.019

[5] G Rivera, P R Calvillo, R Boeri, Y Houbaert and J Sikora, Examination of the solidification macrostructure of spheroidal and flake graphite cast irons using DAAS and ESBD, Mater. Charact. 59 (2008) 1342-1348.

DOI: 10.1016/j.matchar.2007.11.009

[6] N Llorca-Isern, J Tartera, M Espanol, M Marsal, G Bertran and S Castel, Internal features of graphite in cast irons - Confocal microscopy: useful tool for graphite growth imaging, Micron. 33 (2002) 357-364.

DOI: 10.1016/s0968-4328(01)00022-1

[7] A Tiziani, E Ramous and A Molinari, Fracture morphology in compacted graphite cast iron, India, ICF6 New Delhi. 2 (1984) 1489-1496.

DOI: 10.1016/b978-1-4832-8440-8.50139-3

[8] J R Davis, ASM specialty handbook cast irons, ASM International, (1996).

[9] W Oldfield, G T Geering and W A Tiller, Solidification of spheroidal and flake graphite cast iron, Solidification Metals, Iron Steel Insts. 110 (1968) 256-262.

[10] J P Sadocha and J E Gruzleski. Mechanism of Graphite Spheroid Formation in Pure Fe-C-Si Alloys[C]/ Proc. 2 nd Internat. Symposium on the Metallurgy of Cast Iron. 1976, 443-459.

[11] D D Double and A Hellawell, cone-helix growth forms of graphite, Acta Metall. 22 (1974) 481-487.

DOI: 10.1016/0001-6160(74)90101-1

[12] W C Johnson and H B Smartt, role of interphase boundary adsorption in formation of spheroidal graphite in cast-iron, Metall. Mater. Trans. A, 8 (1977) 553-565.

DOI: 10.1007/bf02676976

[13] H. Morrogh and J Williams, graphite formation in cast irons and in nickel carbon and cobalt carbon alloys, Iron Steel Inst. 155 (1947) 321-371.