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SiCp + Cgp Hybrid Composites
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 3 (2016) 235 – 239
Advances in Functional Materials (Conference 2015), AFM 2015
Structure of interface between matrix alloy and reinforcement particles in Al/SiCp + Cgp hybrid composites Anna J. Dolataa*, Maciej Dyziaa, Sonia Boczkalb a
Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, ul. Krasińskiego 8, 40-019 Katowice, Poland b Institute of Non-Ferrous Metals, Light Metals Division, ul. Piłsudskiego 19, 32-050 Skawina, Poland
Abstract The structure and properties of the interface between the components are the primary factor in determining the properties of composite materials, in addition to the properties of the matrix and reinforcing phase. The influence of aluminium matrix chemical composition and its modification on the interface microstructure in Al/SiC p+Cgp hybrid composite were presented. The composites structure was examined under an Olympus GX71 light microscope (LM). Scanning electron microscope (SEM) with an attachment for the chemical analysis (EDS) in microregions was used for the composite microstructure characterization. Copyright © 2014 Elsevier Ltd. All rights reserved. © 2016 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of Conference Committee Members of Advances in Functional Materials Selection and peer-review under responsibility of Conference Committee Members of Advances in Functional Materials (Conference2015). 2015). (Conference Keywords: hybrid composites; stir casting; microstructure; interface;
1. Introduction Foundry aluminum alloys are more and more used as a structural material in composite materials using metal matrix due to their excellent mechanical properties and low weight [1,2]. However presently the most a new research are focus on the formation of structure and properties of functional hybrid aluminium matrix composites [3-8]. Such composites (e.g: Al/SiCp+Cgp or Al/SiCp+GRp) have a better physical, mechanical, and tribological properties in comparison with composite materials reinforced by only one type of reinforcements [4,9]. Due to their beneficial ratio
* Anna J. Dolata. Tel.: +48-32-603-44-26; fax: +48-32-603-44-00. E-mail address: [email protected]
2214-7853 © 2016 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of Conference Committee Members of Advances in Functional Materials (Conference 2015). doi:10.1016/j.matpr.2016.01.063
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Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
of strength to density and better wear resistance it can be used as parts in some vehicles (e.g.: pistons, sleeves, bearings), [6]. The fabrication process by the use of mechanical stirring of composite suspension is the one of the most economical method for manufacturing of such composite materials and has been used in the industrial practice [5,6]. Very important aspects for to obtaining a high quality of composite castings are proper selection of materials and technological parameters in their fabrication [5,7,9]. As known the properties of composite materials in large measure depend on the interface microstructure [8]. Therefore, the primary task of the process for preparing of composites is to obtain good connection of the ceramic phase with the liquid alloy. The poor wetting and high reactivity between liquid Al alloy and ceramic particles such as silicon carbide (SiC) and glassy carbon (C g) are main problems during the production of hybrid composite suspensions [10,11]. There are several methods by which wettability can be improved, for example: applying metal coating on the particles surface (i.e.: Ni, Cu), addition of wetting agents, preheating the particles to remove absorbed gases, increasing the process temperature and adding alloying elements which additionally reduces the surface tension [7,9]. The influence of aluminium matrix chemical composition and its modification on the interface microstructure in AlSi/SiCp+Cgp hybrid composite were presented. 2. Materials and Methods To prepare a composite suspension, the AlSi7Mg foundry alloy was used. The alloy, after melting at 720°C, was refined with argon and modified by 2wt. % Mg and 0.03 wt % Sr. The structure of AlSi7Mg alloy before and after modification presents in Figure 1.
(a)
(c)
(b)
Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
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(d) Figure 1. The structure of AlSi7Mg alloy before (a, b) and (c, d) after modification.
The hybrid mixture of silicon carbide (SiC) and glassy carbon (Cg) particles were used us reinforcing phase (Fig. 2). The procedure of modification aluminium alloy and preparation of hybrid composite suspensions by stir casting method was described in details by authors [3,5,12].
(a)
(b)
Figure 2. The mixture morphology of hybrid SiC and Cg reinforced particles.
The composites structure was examined under an Olympus GX71 light microscope (LM). The structure of the particle/matrix boundaries was observed using a scanning electron microscope (SEM) with an attachment for the chemical analysis in microregions (EDS). 3. Results Analysis of the matrix alloy microstructure has demonstrated a beneficial effect of the applied strontium modification (Fig. 1). Structural tests showed that the acicular structure (characteristic of the unmodified Al alloy, Fig. 1a and Fig. 1b) have changed in the refined, dendritic (Fig. 1c and Fig. 1d). Moreover were achieved a reduction in interfacial distance λ and change in morphology of eutectic silicon. Such effect is preferred in aim to provide adequate mechanical properties of castings. As a result of the conducted composite structure examinations performed by light microscopy, a uniform distribution of the reinforcing phases was confirmed (Fig. 3a). The Cg particles are several times larger than the SiC particles and relatively more dispersed in the matrix. In some areas of the composite sample, small voids around of SiC particles are visible (Fig. 3b). They formed during the preparation of metallographic specimens.
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Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
(a)
(b)
Figure 3. The microstructure of AlSi7Mg2Sr0.03/SiCp+Cgp hybrid composite, (LM).
On the basis of microstructural observations of composites performed at small magnification (LM) the continuous connection between reinforcing particles and the aluminium matrix alloy have been found (Fig.3). Also the microstructural observations conducted by means of scanning electron microscope (SEM) confirmed good connection at the interface between ceramics and matrix alloy (Fig. 4a and Fig. 5a). Linear chemical analysis in microareas carried out in the interface between matrix and particles (both SiC and C g) showed an increase of Mg and O, which may indicate the presence of magnesium oxide in the phase boundary (Fig. 4b and Fig. 5b).
(a)
(b)
Fig. 4. The AlSi7Mg2Sr0.03/SiCp+Cgp composite: a) representative SEM image in boundary area between Al matrix alloy and SiC p; b) linear distribution of elements at the interface, EDS.
In addition have been confirmed an increased concentration of strontium on the surface of the glassy carbon particles and also in boundary areas (Fig. 5b). This proves that the strontium has a positive effect on quality of connection between components.
Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
(a)
(b)
Fig. 5. The AlSi7Mg2Sr0.03/SiCp+Cgp composite: a) representative SEM image in boundary area between Al matrix alloy and C gp; b) linear distribution of elements at the interface, EDS.
4. Conclusions On the basis on results of research proven that the adequate selection of chemical composition of aluminium matrix alloy is very important and have influence on the structure of interface between ceramic reinforcement. This allows obtaining a stable suspension and forming of composite with casting method. Acknowledgements Scientific work financed from funds allocated for The National Centre for Research and Development as project no. PBS1/B6/13/2012. References [1] [2] [3] [4] [5] [6] [7] [8] [9]
[10] [11] [12]
S.V. Prasada, R. Asthana, Aluminum metal–matrix composites for automotive applications: tribological considerations, Tribology Letters 17 (2004) 3, 445-453. Y. Yalcin, H. Akbulut, Dry wear properties of A356-SiC particle reinforced MMCs produced by two melting routes, Materials and Design 27 (2006), 872-881. Anna J. Dolata, Hybrid composites shaped by casting methods, Solid State Phenomena 211 (2014), 47-52, doi:10.4028/www.scientific.net/SSP.211.47. S. Suresha, B.K. Sridhara, Friction characteristics of aluminium silicon carbide graphite hybrid composites, Materials & Design 34 (2012), 576-583. A.J. Dolata, M. Dyzia, Aspects of fabrication aluminium matrix heterophase composites by suspension method, IOP Conf. Series: Materials Science and Engineering 35 (2012) 012020 doi:10.1088/1757-899X/35/1/012020. M. Dyzia, AlSi7Mg/SiC and heterophase SiCp + Cg composite for use in cylinder-piston system of air compressor, Solid State Phenomena 176 (2011), 49-54, doi:10.4028/www.scientific.net/SSP.176.49. A.J. Dolata, M. Dyzia, Effect of chemical composition of the matrix on AlSi/SiCp+Cp composite structure, Archives of Foundry Engineering 14 (2014) 1, 135-138. A. Dolata-Grosz, Interaction of Al-Si alloys with SiC/C ceramic particles and their influence on microstructure of composites, Solid State Phenomena 176 (2011), 55-62. R. S. Rana, Rajesh Purohit, and S Das, Reviews on the influences of alloying elements on the microstructure and mechanical properties of aluminium alloys and aluminum alloy composites, International Journal of Scientific and Research Publications 2 (2012) 6, 1-7, ISSN 2250-3153. K. Landry, S. Kalogeropoulou, N. Eustathopoulos, Wettability of carbon by aluminum and aluminum alloys, Materials Science and Engineering A 254 (1998), 99-111. J. Hashim, L. Looney, M.S.J. Hashmi, The wettability of SiC particles by molten aluminium alloy, J. Mater. Process. Technology 119 (2001) 1-3, 324-328. J. Sleziona, M. Dyzia, A. Dolata-Grosz A, J. Wieczorek, PL Patent No. 391006-A1, Polish Patent Office, 2011.
239
ScienceDirect Materials Today: Proceedings 3 (2016) 235 – 239
Advances in Functional Materials (Conference 2015), AFM 2015
Structure of interface between matrix alloy and reinforcement particles in Al/SiCp + Cgp hybrid composites Anna J. Dolataa*, Maciej Dyziaa, Sonia Boczkalb a
Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, ul. Krasińskiego 8, 40-019 Katowice, Poland b Institute of Non-Ferrous Metals, Light Metals Division, ul. Piłsudskiego 19, 32-050 Skawina, Poland
Abstract The structure and properties of the interface between the components are the primary factor in determining the properties of composite materials, in addition to the properties of the matrix and reinforcing phase. The influence of aluminium matrix chemical composition and its modification on the interface microstructure in Al/SiC p+Cgp hybrid composite were presented. The composites structure was examined under an Olympus GX71 light microscope (LM). Scanning electron microscope (SEM) with an attachment for the chemical analysis (EDS) in microregions was used for the composite microstructure characterization. Copyright © 2014 Elsevier Ltd. All rights reserved. © 2016 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of Conference Committee Members of Advances in Functional Materials Selection and peer-review under responsibility of Conference Committee Members of Advances in Functional Materials (Conference2015). 2015). (Conference Keywords: hybrid composites; stir casting; microstructure; interface;
1. Introduction Foundry aluminum alloys are more and more used as a structural material in composite materials using metal matrix due to their excellent mechanical properties and low weight [1,2]. However presently the most a new research are focus on the formation of structure and properties of functional hybrid aluminium matrix composites [3-8]. Such composites (e.g: Al/SiCp+Cgp or Al/SiCp+GRp) have a better physical, mechanical, and tribological properties in comparison with composite materials reinforced by only one type of reinforcements [4,9]. Due to their beneficial ratio
* Anna J. Dolata. Tel.: +48-32-603-44-26; fax: +48-32-603-44-00. E-mail address: [email protected]
2214-7853 © 2016 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of Conference Committee Members of Advances in Functional Materials (Conference 2015). doi:10.1016/j.matpr.2016.01.063
236
Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
of strength to density and better wear resistance it can be used as parts in some vehicles (e.g.: pistons, sleeves, bearings), [6]. The fabrication process by the use of mechanical stirring of composite suspension is the one of the most economical method for manufacturing of such composite materials and has been used in the industrial practice [5,6]. Very important aspects for to obtaining a high quality of composite castings are proper selection of materials and technological parameters in their fabrication [5,7,9]. As known the properties of composite materials in large measure depend on the interface microstructure [8]. Therefore, the primary task of the process for preparing of composites is to obtain good connection of the ceramic phase with the liquid alloy. The poor wetting and high reactivity between liquid Al alloy and ceramic particles such as silicon carbide (SiC) and glassy carbon (C g) are main problems during the production of hybrid composite suspensions [10,11]. There are several methods by which wettability can be improved, for example: applying metal coating on the particles surface (i.e.: Ni, Cu), addition of wetting agents, preheating the particles to remove absorbed gases, increasing the process temperature and adding alloying elements which additionally reduces the surface tension [7,9]. The influence of aluminium matrix chemical composition and its modification on the interface microstructure in AlSi/SiCp+Cgp hybrid composite were presented. 2. Materials and Methods To prepare a composite suspension, the AlSi7Mg foundry alloy was used. The alloy, after melting at 720°C, was refined with argon and modified by 2wt. % Mg and 0.03 wt % Sr. The structure of AlSi7Mg alloy before and after modification presents in Figure 1.
(a)
(c)
(b)
Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
237
(d) Figure 1. The structure of AlSi7Mg alloy before (a, b) and (c, d) after modification.
The hybrid mixture of silicon carbide (SiC) and glassy carbon (Cg) particles were used us reinforcing phase (Fig. 2). The procedure of modification aluminium alloy and preparation of hybrid composite suspensions by stir casting method was described in details by authors [3,5,12].
(a)
(b)
Figure 2. The mixture morphology of hybrid SiC and Cg reinforced particles.
The composites structure was examined under an Olympus GX71 light microscope (LM). The structure of the particle/matrix boundaries was observed using a scanning electron microscope (SEM) with an attachment for the chemical analysis in microregions (EDS). 3. Results Analysis of the matrix alloy microstructure has demonstrated a beneficial effect of the applied strontium modification (Fig. 1). Structural tests showed that the acicular structure (characteristic of the unmodified Al alloy, Fig. 1a and Fig. 1b) have changed in the refined, dendritic (Fig. 1c and Fig. 1d). Moreover were achieved a reduction in interfacial distance λ and change in morphology of eutectic silicon. Such effect is preferred in aim to provide adequate mechanical properties of castings. As a result of the conducted composite structure examinations performed by light microscopy, a uniform distribution of the reinforcing phases was confirmed (Fig. 3a). The Cg particles are several times larger than the SiC particles and relatively more dispersed in the matrix. In some areas of the composite sample, small voids around of SiC particles are visible (Fig. 3b). They formed during the preparation of metallographic specimens.
238
Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
(a)
(b)
Figure 3. The microstructure of AlSi7Mg2Sr0.03/SiCp+Cgp hybrid composite, (LM).
On the basis of microstructural observations of composites performed at small magnification (LM) the continuous connection between reinforcing particles and the aluminium matrix alloy have been found (Fig.3). Also the microstructural observations conducted by means of scanning electron microscope (SEM) confirmed good connection at the interface between ceramics and matrix alloy (Fig. 4a and Fig. 5a). Linear chemical analysis in microareas carried out in the interface between matrix and particles (both SiC and C g) showed an increase of Mg and O, which may indicate the presence of magnesium oxide in the phase boundary (Fig. 4b and Fig. 5b).
(a)
(b)
Fig. 4. The AlSi7Mg2Sr0.03/SiCp+Cgp composite: a) representative SEM image in boundary area between Al matrix alloy and SiC p; b) linear distribution of elements at the interface, EDS.
In addition have been confirmed an increased concentration of strontium on the surface of the glassy carbon particles and also in boundary areas (Fig. 5b). This proves that the strontium has a positive effect on quality of connection between components.
Anna J. Dolata et al. / Materials Today: Proceedings 3 (2016) 235 – 239
(a)
(b)
Fig. 5. The AlSi7Mg2Sr0.03/SiCp+Cgp composite: a) representative SEM image in boundary area between Al matrix alloy and C gp; b) linear distribution of elements at the interface, EDS.
4. Conclusions On the basis on results of research proven that the adequate selection of chemical composition of aluminium matrix alloy is very important and have influence on the structure of interface between ceramic reinforcement. This allows obtaining a stable suspension and forming of composite with casting method. Acknowledgements Scientific work financed from funds allocated for The National Centre for Research and Development as project no. PBS1/B6/13/2012. References [1] [2] [3] [4] [5] [6] [7] [8] [9]
[10] [11] [12]
S.V. Prasada, R. Asthana, Aluminum metal–matrix composites for automotive applications: tribological considerations, Tribology Letters 17 (2004) 3, 445-453. Y. Yalcin, H. Akbulut, Dry wear properties of A356-SiC particle reinforced MMCs produced by two melting routes, Materials and Design 27 (2006), 872-881. Anna J. Dolata, Hybrid composites shaped by casting methods, Solid State Phenomena 211 (2014), 47-52, doi:10.4028/www.scientific.net/SSP.211.47. S. Suresha, B.K. Sridhara, Friction characteristics of aluminium silicon carbide graphite hybrid composites, Materials & Design 34 (2012), 576-583. A.J. Dolata, M. Dyzia, Aspects of fabrication aluminium matrix heterophase composites by suspension method, IOP Conf. Series: Materials Science and Engineering 35 (2012) 012020 doi:10.1088/1757-899X/35/1/012020. M. Dyzia, AlSi7Mg/SiC and heterophase SiCp + Cg composite for use in cylinder-piston system of air compressor, Solid State Phenomena 176 (2011), 49-54, doi:10.4028/www.scientific.net/SSP.176.49. A.J. Dolata, M. Dyzia, Effect of chemical composition of the matrix on AlSi/SiCp+Cp composite structure, Archives of Foundry Engineering 14 (2014) 1, 135-138. A. Dolata-Grosz, Interaction of Al-Si alloys with SiC/C ceramic particles and their influence on microstructure of composites, Solid State Phenomena 176 (2011), 55-62. R. S. Rana, Rajesh Purohit, and S Das, Reviews on the influences of alloying elements on the microstructure and mechanical properties of aluminium alloys and aluminum alloy composites, International Journal of Scientific and Research Publications 2 (2012) 6, 1-7, ISSN 2250-3153. K. Landry, S. Kalogeropoulou, N. Eustathopoulos, Wettability of carbon by aluminum and aluminum alloys, Materials Science and Engineering A 254 (1998), 99-111. J. Hashim, L. Looney, M.S.J. Hashmi, The wettability of SiC particles by molten aluminium alloy, J. Mater. Process. Technology 119 (2001) 1-3, 324-328. J. Sleziona, M. Dyzia, A. Dolata-Grosz A, J. Wieczorek, PL Patent No. 391006-A1, Polish Patent Office, 2011.
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