N. B. Pugacheva, I. Yu. Malygina, N. S. Michurov, E. I. Senaeva, N. P. Antenorova

EFFECT OF HEAT TREATMENT ON THE STRUCTURE AND PHASE COMPOSITION OF ALUMINUM MATRIX COMPOSITES CONTAINING SILICON CARBIDE

The paper studies the microstructure, phase and chemical compositions and hardness of composites with a D16 alloy matrix and SiC as a filler in the amounts of 10, 20 and 30 % after quenching from 540 °С followed by aging at temperatures of 120 and 170 °С. It has been found that the matrix has a grain structure, the grain size being determined by the size of the granules; namely, the coarser the granules (5 to 150 µm), the larger the grains (0.05 to 5 µm, respectively). Needle-shaped particles, up to 2 µm long and 0.5 µm wide, of the S-phase of Al2CuMg precipitate on the matrix grain boundaries. At a quenching temperature of 540 °С, all the reinforcing intermetallics dissolve in the metal matrix, with the formation of low-melting eutectics according to the reaction α + S(Al2CuMg) → L; eutectic structural constituents of two chemical compositions are formed – one including the copper- and zinc-enriched S-phase, the other containing magnesium. Herewith, the melt flows into the micropores among the filler particles, this being manifested especially clearly in the composite with 30 vol % SiC. Silicon carbide partially dissolves with the formation of Al4SiC4. Hardness measurements demonstrate that, after sintering, in the initial composites there are internal micropores at the interfaces of three and more SiC filler particles, and this decreases hardness from 107 HV 5 at 5% SiC to 71.6 HV 5 at 30 % SiC. Heating and holding at 540 °С increases the values of hardness due to lower porosity, these values being further increased by aging at 120 and 170 °C. It is proposed that heating to 540 °С be used to perform heat-deformation processing of the studied composites after sintering in order to decrease porosity, to ensure strong diffusion bonding of the matrix to the filler particles and to form the most homogeneous possible structure, aging at 120 or 170 °С being used for the final hardening of finished products.

References:

1. Fernández R., González-Doncel G. Understanding the creep fracture behavior of aluminum alloys and aluminum alloy metal matrix composites. Materials Science and Engineering: A, 2011, vol. 528, iss. 28, pp. 8218–8225. DOI: 10.1016/j.msea.2011.07.027
2. Yishi S., Qiubao O., Wenlong Z., Zhiqiang L., Qiang G., Genlian F., Di Z. Composite structure modeling and mechanical behavior of particle reinforced metal matrix composites. Mater. Sci. Eng. A., 2014, vol. 597, pp. 359–369. DOI: 10.1016/j.msea.2014.01.024
3. Zhao Long-Zhi, Zhao Ming-Juan, Yan Hong, Cao Xiao-Ming, Zhang Jin-Song. Mechanical behavior of SiC foam-SiC particles/Al hybrid composites. Transactions of Nonferrous Metals Society of China, 2009, vol. 19, pp. 547–551. DOI: 10.1016/S10036326(10)60106-9
4. Ortega-Celaya F., Pech-Canul M.I., Lopes-Cuevars J., Rendon-Angeles J.C., Pech-Canul M.A. Microstructure and impact behavior of Al/SiCp composites fabricated by pressureless infiltration with different types of SiCp. Journal of Materials Processing Technology, 2007, vol. 183,
   nos. 2–3, pp. 368–373. DOI: 10.1016/j.jmatprotec.2006.10.029
5. Konovalov A.V., Smirnov S.V. The state of the art and lines of research in the field of Al/SiC metal matrix composites. Konstruktsii iz  Kompozitsionnykh Materialov, 2015, no. 1, pp. 30–35. (In Russian).
6. Pugacheva N.B., Michurov N.S., Bikova T.M. The Structure and Properties of the 30Al-70SiC Metal Matrix Composite Material. Diagnostics, Resource and Mechanics of materials and structures, 2015, iss. 6, pp. 6–18. Available at: http://dreamjournal.org/issues/2015-6/2015-6_56.html 11
7. Pugacheva N.B., Michurov N.S., Bykova T.M. Structure and properties of the Al/SiC composite material. Physics of Metals and Metallography, 2016, vol. 117, no. 6, pp. 634–640. DOI: 10.1134/S0031918X16060119
8. Smirnov A.S., Konovalov A.V., Muizemnek O.Yu. Modelling and Simulation of Strain Resistance of Alloys Taking into Account Barrier Effects. Diagnostics, Resource and Mechanics of materials and structures, 2015, iss. 1, pp. 61–72. Available at: http:// dream-journal.org/issues/2015-1/2015-1_18.html
9. Khalevitsky Yu.V., Myasnikova M.V., Konovalov A.V. Ways of creating a computational model of the representative volumes an Al/SiC metal matrix composite with an internal structure. Matematicheskoe Modelirovanie v Estestvennykh Naukakh, 2014, vol. 1, pp. 277–280. (In Russian).
10. Kolachev B.A., Yelagin V.I., Livanov V.A. Metallovedenie i termicheskaya obrabotka metallov [Metal Science and Heat Treatment of Metals]. М, MISIS Publ., 2001, 416 p. (In Russian).
11. Fridlyander I.N. Modern Aluminum and Magnesium Alloys and Composite Materials Based on Them. Metal Science and Heat Treatment, 2002, vol. 44, iss 7, pp. 292–296. DOI: 10.1023/A: 1021255804324
12. Lee Doh-Jae, Vaudin M.D., Handewerker C.A., Katter U.R. Phase Stability and Interface Reactions in the Al-SiC System. In: Mater. Res. Symp. Proc., 1988, vol. 120, pp. 293. DOI: 10.1557/PROC-120-357
13. Ibrahim A.I., Mohamed F.A., Lavernia E.J. Particular reinforced metal matrix composites – a review. Journal of Materials Science, 1991, vol. 26, iss. 5, pp. 1137–1156. DOI: 10.1007/BF00544448
14. Pugacheva N.B., Michurov N.S., Senaeva E.I. Structure and thermophysical properties of aluminum-matrix composites. Physics of Metals and Metallography, 2016, no. 11, pp. 1144–1151. DOI: 10.1134/S0031918X16110119

Article reference