Savrai R.A., Malygina I.Yu. 2019 Vol. 21 No. 4

OBRABOTKAMETALLOV Vol. 21 No. 4 2019 81 MATERIAL SCIENCE Effect of Laser Alloying with the Powder Mixtures of Cu–Zn–Ti and Si–Cu on the Structure and Properties of Cast Aluminum Alloy Roman Savrai 1, a,* , Irina Malygina 1, b , Aleksey Makarov 1, 2, 3, c , Alevtina Osintseva 1, d , Svetlana Rogovaya 1, e , Yuri Kolobylin 1, f 1 Institute of Engineering Science, Ural Branch, Russian Academy of Sciences, 34 Komsomolskaya St., Ekaterinburg, 620049, Russian Federation 2 M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18 S. Kovalevskaya st., Ekaterinburg, 620108, Russian Federation 3 Ural Federal University named after the first President of Russia B.N. Yeltsin, 19 Mira st., Ekaterinburg, 620002, Russian Federation a https://orcid.org/0000-0001-9873-3621, ras@imach.uran.ru, b https://orcid.org/0000-0002-9463-1473 , malygina@imach.uran.ru, c http://orcid.org/0000-0002-2228-0643, avm@imp.uran.ru , d https://orcid.org/0000-0003-0043-8435, osintseva@imach.uran.ru , e https://orcid.org/0000-0002-3895-7284, rogovaya@imach.uran.ru , f https://orcid.org/0000-0002-7831-2624, uramk@mail.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2019 vol. 21 no. 4 pp. 70–84 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2019-21.4-70-84 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ARTICLE INFO Article history : Received: 01 August 2019 Revised: 26 September 2019 Accepted: 07 October 2019 Available online: 15 December 2019 Keywords : Cast aluminum alloy Laser surface alloying Microstructure Phase composition Microhardness Microindentation Abrasive wear resistance Resistance to thermal erosion Funding This work is done within the Complex Program of UB RAS, project No. 18-10- 1-40, with regard to the studied material and methods of its processing, and within the state orders for IES UB RAS, reg. no. АААА-А18-118020790147-4, and IMP UB RAS, reg. no. АААА-А18-118020190116-6, with regard to the measurements of micro- mechanical characteristics and evaluation of resistance to elastic-plastic deformation. Scanning electron microscopy and micro- mechanical tests were performed in Col- lective Use Center “Plastometriya” of the Institute of Engineering Science UB RAS. ABSTRACT Introduction. The use of laser based modification technologies is an actual and promising way to improve the surface properties of aluminum alloys. Laser alloying of aluminum alloys, which helps to improve its corrosion resistance, mechanical properties and wear resistance under conditions of adhesion and abrasive wear, is of great interest. The aim of this work is to study the possibility of increasing the physical and mechanical properties of the cast aluminum alloy by laser alloying with the powder mixtures of Cu–Zn–Ti (blend no. 1) and Si–Cu (blend no. 2), which are applied to the surface of specimens in the form of coatings. Laser alloying of the surface of specimens is carried out on a continuous CO 2 laser with the emission wavelength λ = 10.6 μm. The methods of investigation. Optical and scanning electron microscopy, energy-dispersive microanalysis, x-ray diffraction phase analysis, microhardness measurement, instrumented microindentation, abrasive wear and thermal erosion tests are used. Results and discussion. It is established that the laser alloying results in the formation of alloyed layers with a depth h = 3.5–4.0 mm on the surface of the aluminum alloy specimens. The alloyed layers have a dendritic-cellular structure, the main structural components of which are the α–Al solid solution and a network of eutectic silicon crystals along the boundaries of dendritic cells. The CuAl 2 intermetallide with a particle size of 1–5 μm also is detected in the structure of the alloyed layers. The laser alloying increases the hardness of the aluminum alloy from 90 to 125 HV 0.025 after alloying with the powder blend no. 1 and up to 100 HV 0.025 after alloying with the powder blend no. 2. According to the microindentation data, the alloyed layers are characterized by increased resistance to elastic-plastic deformation, which is evidenced by the increase in the parameters of R e in 1.2–1.38 times, H IT /E * in 1.33–1.67 times and 3 *2 IT H E in 2.14–3.71 times. Wear resistance tests under conditions of abrasive wear shows that the laser alloying leads to some increase in wear rate Ih (decrease in wear resistance) of the aluminum alloy from (1.49±0.09)10 −3 to (1.82±0.06)10 −3 after alloying with the powder blends no. 1 and 2. However, laser alloying the alloy leads to an increase in its resistance to thermal erosion, which manifests itself in reducing the number and size of thermal cracks. ______ * Corresponding author Savrai Roman A. , Ph.D. (Engineering), Head of laboratory Institute of Engineering Science, Ural Branch, Russian Academy of Sciences, 34 Komsomolskaya St., Ekaterinburg, 620049, Russian Federation Tel.: +7 (343) 362-30-14, e-mail: ras@imach.uran.ru For citation: Savrai R.A., Malygina I.Yu., Makarov A.V., Osintseva A.L., Rogovaya S.A., Kolobylin Yu.M. Effect of laser alloying with the powder mixtures of Cu–Zn–Ti and Si–Cu on the structure and properties of cast aluminum alloy. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science , 2019, vol. 21, no. 4, pp. 70–84. DOI: 10.17212/1994-6309-2019-21.4- 70-84. (In Russian).