Al-Ni in situ surface composites were fabricated by friction stir processing method. Friction stir processing produced a composite with nickel and NiAl3 as reinforcement particles in aluminium matrix. The particles were fine and were in the submicrometer size range. The separation distance between the particles was very small. Impression creep experiments were conducted on the samples both at friction stir zone and base material zone at various temperatures. Steady state creep rates were estimated, and activation energy for creep was calculated. It is observed that the friction stir zone offered a higher creep resistance compared to the base metal zone. Higher creep resistance is attributed to the dissolution of nickel atoms into aluminium matrix and the presence of fine nickel particles and NiAl3 precipitates. The measured activation energy indicated that the associated creep mechanism is the dislocation creep in the temperature range of 30–150°C, both in friction stir zone and base metal zone. At higher temperatures (150–180°C) the diffusion creep mechanism is suggested. 1. Introduction Aluminum and its alloys have versatile properties which make them suitable for use in a variety of applications [1]. In many of the applications, the surface needs to have better mechanical properties like improved strength and better hardness. Having a metal matrix composite at the surface is one of the optiones to have better resistance to wear, improved hardness, and even to an extent high-temperature stability at the surface [2]. Friction stir processing (FSP) is a new metal working method for producing surface composite. It is based on the concept of friction stir welding (FSW) [3]. During friction stir processing, the stirred material undergoes severe plastic deformation. The material flow associated with stirring and severe plastic deformation can be used for bulk alloy modification by the mixing of second elements, mixing followed by the precipitation of second phases, distribution of fine particles of second element, increased density of defects, and so forth. As a result, the stirred zone becomes a metal matrix composite with an improved hardness and wear resistance [4]. Arora et al. [5] have reviewed composite fabrication using FSP route. Mishra et al. [6] have used this route to make a surface composite on AA 5083 alloy with 0.7？μm SiC particles. Shafiei-Zarghani et al. [7] and Mahmoud et al. [8] have incorporated Al2O3 and SiC particles to substrates like Al, Cu, and Fe alloys and observed an improvement in the abrasion and wear resistance of the surface
References
[1]
R. E. Smallman and R. J. Bishop, Modern Physical Metallurgy and Materials Engineering, Butterworth Publishing, New York, NY, USA, 6th edition, 1999.
[2]
T. P. D. Rajan, R. M. Pillai, and B. C. Pai, “Functionally graded Al-Al3Ni in situ intermetallic composites: fabrication and microstructural characterization,” Journal of Alloys and Compounds, vol. 453, no. 1-2, pp. L4–L7, 2008.
[3]
R. S. Mishra and Z. Y. Ma, “Friction stir welding and processing,” Materials Science and Engineering R, vol. 50, no. 1-2, pp. 1–78, 2005.
[4]
D. Yadav and R. Bauri, “Nickel particle embedded aluminium matrix composite with high ductility,” Materials Letters, vol. 64, no. 6, pp. 664–667, 2010.
[5]
H. S. Arora, H. Singh, and B. K. Dindaw, “Composite fabrication using friction stir processing—a review,” The International Journal of Advanced Manufacturing Technology, vol. 61, no. 9–12, pp. 1043–1055, 2012.
[6]
R. S. Mishra, Z. Y. Ma, and I. Charit, “Friction stir processing: a novel technique for fabrication of surface composite,” Materials Science and Engineering A, vol. 341, no. 1-2, pp. 307–310, 2003.
[7]
A. Shafiei-Zarghani, S. F. Kashani-Bozorg, and A. Zarei-Hanzaki, “Microstructures and mechanical properties of Al/Al2O3 surface nano-composite layer produced by friction stir processing,” Materials Science and Engineering A, vol. 500, no. 1-2, pp. 84–91, 2009.
[8]
E. R. I. Mahmoud, K. Ikeuchi, and M. Takahashi, “Fabrication of SiC particle reinforced composite on aluminium surface by friction stir processing,” Science and Technology of Welding and Joining, vol. 13, no. 7, pp. 607–618, 2008.
[9]
Z. Y. Ma and R. S. Mishra, “Cavitation in superplastic 7075 Al alloys prepared via friction stir processing,” Acta Materialia, vol. 51, no. 12, pp. 3551–3569, 2003.
[10]
A. Dolatkhah, P. Golbabaei, M. K. Besharati Givi, and F. Molaiekiya, “Investigating effects of process parameters on microstructural and mechanical properties of Al5052/SiC metal matrix composite fabricated via friction stir processing,” Materials and Design, vol. 37, pp. 458–464, 2012.
[11]
I. S. Lee, P. W. Kao, and N. J. Ho, “Microstructure and mechanical properties of Al-Fe in situ nanocomposite produced by friction stir processing,” Intermetallics, vol. 16, no. 9, pp. 1104–1108, 2008.
[12]
C. J. Hsu, P. W. Kao, and N. J. Ho, “Intermetallic-reinforced aluminum matrix composites produced in situ by friction stir processing,” Materials Letters, vol. 61, no. 6, pp. 1315–1318, 2007.
[13]
D. Yadav and R. Bauri, “Processing, microstructure and mechanical properties of nickel particles embedded aluminium matrix composite,” Materials Science and Engineering A, vol. 528, no. 3, pp. 1326–1333, 2011.
[14]
L. Ke, C. Huang, L. Xing, and K. Huang, “Al-Ni intermetallic composites produced in situ by friction stir processing,” Journal of Alloys and Compounds, vol. 503, no. 2, pp. 494–499, 2010.
[15]
J. Qian, J. Li, J. Xiong, F. Zhang, and X. Lin, “Insitu synthesizing Al3Ni for fabrication of intermetallic reinforced aluminium alloy composites by friction stir processing,” Materials Science and Engineering A, vol. 550, pp. 279–285, 2012.
[16]
D. H. Sastry, “Impression creep technique—an overview,” Materials Science and Engineering A, vol. 409, no. 1-2, pp. 67–75, 2005.
[17]
R. A. Higgins, Engineering Metallurgy, Arnold Publishing, New York, NY, USA, 6th edition, 1993.
[18]
H. Baker and H. Okamoto, ASM Handbook, vol. 3 of Alloy Phase Diagrams, ASM International, Materials Park, Ohio, USA, 1992.
[19]
M. Atapour, A. Pilchak, G. S. Frankel, and J. C. Williams, “Corrosion behaviour of investment cast and friction stir processed Ti-6Al-4V,” Corrosion Science, vol. 52, no. 9, pp. 3062–3069, 2010.
[20]
C. W. Yang, “Tensile mechanical properties and failure behaviors of friction stir processing (FSP) modified Mg-Al-Zn and dual-phase Mg-Li-Al-Zn alloys,” in Materials Science: Advanced Topics, Y. Mastai, Ed., InTech, 2013.
[21]
C.-F. Chen, P.-W. Kao, L. Chang, and N.-J. Ho, “Mechanical properties of nanometric Al2O3 particulate-reinforced Al-Al11Ce3 composites produced by friction stir processing,” Materials Transactions, vol. 51, no. 5, pp. 933–938, 2010.
[22]
H. Sieber, J. S. Park, J. Weissmüller, and J. H. Perepezko, “Structural evolution and phase formation in cold-rolled aluminum-nickel multilayers,” Acta Materialia, vol. 49, no. 7, pp. 1139–1151, 2001.
[23]
F. A. Mohamed and T. G. Langdon, “Deformation mechanism maps based on grain size,” Metallurgical Transactions, vol. 5, no. 11, pp. 2339–2345, 1974.
[24]
Y. Li and T. G. Langdon, “Creep behavior of an Al-6061 metal matrix composite reinforced with alumina particulates,” Acta Materialia, vol. 45, no. 11, pp. 4797–4806, 1997.
[25]
H. Takagi, M. Dao, M. Fujiwara, and M. Otsuka, “Experimental and computational creep characterization of Al-Mg solid-solution alloy through instrumented indentation,” Philosophical Magazine, vol. 83, no. 35, pp. 3959–3976, 2003.
[26]
O. D. Sherbi and J. Wordsworth, “Deformation processing and structure,” in ASM Handbook, chapter 8, American Society for Metals, Metal Park, Ohio, USA, 1984.
