Al–FeAl–TiAl–Al2O3 composite with hybrid reinforcement

Journal of Materials Processing Technology 162–163 (2005) 33–38

Al–FeAl–TiAl–Al2O3 composite with hybrid reinforcement A. Dolata-Grosz a,b,∗ , B. Formanek a,c , a,b , J. Wieczorek a,b ´ J. Sleziona a

Silesian University of Technology, Faculty of Materials Science and Metallurgy, Str. Krasi´nskiego 8, PL-40-019 Katowice, Poland b Department of Metal Alloy and Composites of Technology, Poland c Department of Material Science, Poland

Abstract The process of obtaining cast aluminium composite of dispersive structure and hybrid reinforcement has been presented in the article. An Aluminium alloy (AlMg2 ) was modified with a powder mixture which, when in reaction with aluminium, reinforced the matrix with intermetallic phases and aluminium oxide. According to the technological conception, an assumption was made, that the cast composites would be produced in technological procedure shown in Fig. 1. The reinforcing phases were using Fe–Ti–Al powder mixtures with aluminium oxide formed in a self-propagating high-temperature synthesis (SHS). The structure and phase composition of the composite powder used for the matrix alloy modification are shown in Fig. 2. A composite alloy Al–FeAl–TiAl–Al2 O3 was produced by casting method (gravity casting, mechanical mixing) after which its structure was determined. It was assumed that the final product of the applied production process will be an aluminium composite with hybrid reinforcement, consisting of Fe–Al and Ti–Al intermetallic phases and aluminium oxides. Optical microscopy, electron scanning microscopy and X-ray phase analysis were used to characterize the microstructure of the composites produced. Presence of aluminium, Al3 Ti and Al13 Fe4 phases and dispersed Al2 O3 was confirmed in the composite by XRD method. The dispersion structure and phase composition of the composites are presented in Figs. 3–6. The composites formed in an in situ reaction constitute a newer generation of casts, in which dispersion reinforcement is obtained in the form of intermetallic and ceramic phases coherent with the matrix, very often below 1 ␮m in size. The designed process allows for the structure modification of the applied casting aluminium alloys in different technological variants. © 2005 Elsevier B.V. All rights reserved. Keywords: Aluminium alloy; Composite powders; Intermetallic phases; Gravity casing; Structure

1. Introduction Selection of an adequate method of composite production as well as the type, size and distribution of reinforcement have a direct influence on the composite’s structure, which in turn determinates the properties of the finished product [1–12]. Among the industrial methods of aluminum metal matrix composites (AMMCs) production, as much as a 10% share belongs to the mechanical stirring method [3]. Particle aluminum metal matrix composites (PAMMCs) produced by casting methods have found applications in the aerospace, military, and especially in the automotive indus∗

Corresponding author. Tel.: +48 32 6034367; fax: +48 32 6034469. E-mail address: [email protected] (A. Dolata-Grosz).

0924-0136/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2005.02.009

tries [13]. Known technical and technological solutions of metal–ceramic suspensions production use particles, most frequently SiC and Al2 O3 , of at least a dozen or so ␮m in size [4–12]. In those cases, one can observe an increase in the material’s modulus of elasticity, hardness and abrasion resistance, and simultaneously a decrease in its tensile strength and plasticity [7–10]. In order to obtain considerable effects of reinforcement, very small particles with good plastic properties, about 1 ␮m in size (or smaller), are to be incorporated into the metallic matrix. For casting methods, however, the problem of incorporating such small particles has not been solved so far. An obstacle are both convection currents of gases above the surface of a mechanically stirred liquid metal as well as phenomena of small particles agglomera-

34

A. Dolata-Grosz et al. / Journal of Materials Processing Technology 162–163 (2005) 33–38

tion and lack of wetting their surfaces with liquid metals [11,12]. The methods of incorporating fine dispersed particles into a liquid metal applied up to now consist in taking advantage of the in situ reaction between a liquid metal (or a chemical element being a component of the alloy) and the incorporated reacting substance (most frequently gas, e.g. oxidation of Al by oxygen), run-purge with Cn Hm gases, as a result of which dissociation and carbides formation occur [14–21]. The exchange reactions, which proceed between Al and the incorporated oxides of high dispersion (particles of a few dozen ␮m in size), can be applied as well. An example of such a solution is the application of oxides like CuO [18]. Another solution allowing the incorporation of fine dispersed particles into Al alloys is to apply a mechanical alloying (MA) process in which Al powder is combined with ceramic powder [22–24]. The application of appropriate grinding and agglomerating parameters leads to ceramic particles size reduction to a size of about 1 ␮m and their incorporation into Al powder. Such powders are very easy to incorporate into a liquid aluminum alloy, distribute in it and homogenize [25,26]. As the research carried out has shown, the problem of obtaining dispersion reinforcement in the matrix alloy using the mechanical stirring method can be also solved, according to the authors’ proposal, by modification of Al alloy with composite powder mixtures produced by SHS method [27–30]. In a reaction with liquid Al, the composite powder mixtures reinforce the matrix with intermetallic and ceramic phases of high dispersion. Composites produced “in situ” are described as composite materials of new generation. As opposed to “ex situ” composites [7–10], the former ones are characterized by high thermodynamic stability which counteracts the chemical reactions at the matrix/reinforcing particle border, and

reduces the structure degradation during work at elevated temperatures [21,22]. This paper presents only a fragment of investigations conducted by article’s authors on the use of chemically active and passive composite powders obtained in the SHS process (selfpropagating high-temperature synthesis) for the production of hybrid composites reinforced with intermetallic phases and fine dispersed ceramic particles produced by casting methods (mechanical stirring and centrifugal casting) [19,25–30].

2. Purpose and scope of the research The main purpose of the research was to determine the chemical composition of metallic–ceramic powders and the process of production aluminium-based composite casts with hybrid reinforcement of high phase dispersion. The scope of the research covered: • literature analysis of composite materials production with regard to casting methods and powder metallurgy; • development of a material and technological concept of composite material production (Fig. 1); • selection of chemical compositions of metallic–ceramic powder mixtures; • carrying out the initial research with the purpose of the basic material production parameters determination in the accepted technological cycle; • determination of structure and phase composition of the chosen composite powders and the produced composite casts; • correction of parameters in the technological cycle of producing aluminium casts of the assumed dispersive structure and phase composition of the reinforcement.

Fig. 1. The scheme of the technological procedure of cast composite manufacturing with hybrid reinforcement.

A. Dolata-Grosz et al. / Journal of Materials Processing Technology 162–163 (2005) 33–38

3. Materials and methodology of research For the assumed analytic purposes, powder materials, aluminium alloys, technological devices and research methods chosen allowed the production of a composite material of an aluminium matrix composites type (AMCs). Selection of materials and methods for the composite material production included application of powder metallurgy [27] and casting processes [7]. The production processes scheme of the composite cast is shown in Fig. 1. For the purpose of powder mixtures production, ilmenite and powders of aluminium as the substrate [19,31], of a pure sort were used. Sinters of the composite were produced in a high-temperature synthesis process (SHS) followed by crushing, milling in a rotary-vibration mill and separation into adequate fractions. The powders were introduced into liquid aluminium alloys at the temperature scope from 700◦ to 720◦ . Aluminium was modified with magnesium up to 2% of its content in the bath. In the casting process of the composite material production, resistance furnaces were used. The mixture of powders was introduced into melted aluminium

35

in a rotary motion and stirred mechanically for 30 min. The composites produced were cast into a graphite mould. The powders and casts structure was observed on metallographic specimens, using the Reichert MF2 microscope with digital camera for the photographs registration. The chosen specimens were analysed using a Hitachi scanning microscope equipped with EDX equipment, in Norton’s Voyager system. The phase composition of the composite powders and casts was analysed with the use of Philips diffractometer with copper lamp and carbon beam filter. The diffraction patterns were analysed by means of ASTA cards and X-Pert Software programme.

4. The research results The structure and phase composition of selected reactive powder FeAl–TiAl–Al2 O3 are shown in Fig. 2. The dispersion structure of composite casts is presented in Fig. 3. On the basis of structural investigations (Figs. 3, 4(b), 5 and 6) as well as an X-ray analysis (Fig. 4(a)), the occurrence of

Fig. 2. Diffraction pattern of FeAl–TiAl–Al2 O3 composite powder after producing by the SHS process (a) and the structure of FeAl–TiAl–Al2 O3 initial powder mixture used for the matrix alloy modification after size reduction in a rotary-vibration mill (b).

Fig. 3. The dispersive structure of Al–FeAl–TiAl–Al2 O3 cast composite after casting at the 720 ◦ C into the grafite mould.

36

A. Dolata-Grosz et al. / Journal of Materials Processing Technology 162–163 (2005) 33–38

Fig. 4. Diffraction pattern (a) and the microstructure of Al–FeAl–TiAl–Al2 O3 cast composites with intermetallic phases and aluminium oxides (particulate of phases marks on the picture) (b).

Fig. 5. The microstructures (a) and fracture surface (b) of Al–FeAl–TiAl–Al2 O3 cast composite; the lamellar and acicular phases with the AlFe system and dispersive Al2 O3 particles are visible on the pictures.

Fig. 6. The microstructure of Al–FeAl–TiAl–Al2 O3 cast composite with hybrid reinforcement.

A. Dolata-Grosz et al. / Journal of Materials Processing Technology 162–163 (2005) 33–38

the aluminium matrix reinforced with intermetallic and ceramic phases has been confirmed. The fabricated composite casts were characterized by a dispersive structure of a predefined chemical and phase composition. The presence of aluminium, Al3 Ti and Al13 Fe4 phases and dispersed Al2 O3 in the composite was identified according to XRD pattern (Fig. 4). That fabricated composite casts were characterized by a dispersive structure of a predefined chemical and phase composition. The size of reinforcing particles were in correlation with granulation of the powder used. For all the composite casts the uniform particles distribution was observed. It needs to be emphasised that while introducing the powders mixture into liquid metal, an exothermal effect of the reactions in progress was observed. According to the assumptions and on the basis of the earlier thermodynamic analysis and thermal differential analysis, the matrix reinforcement can be written down by means of the following reactions: FeAl + TiAl + Al2 O3 + (x + 4)Al → FeAl3 + TiAl3 + Al2 O3 + xAl

(1)

The composites formed in the course of the in situ reaction constitute a newer generation of casts with intermetallic and ceramic dispersive phases, coherences with the matrix, very often below 1 ␮m in size (Figs. 5 and 6).

5. Summary The production technology of aluminium matrix composite casts with hybrid reinforcement of high dispersion of phases is presented in the article. The technological cycle includes: • production of mixture of powders of complicated and assumed chemical composition and reactivity with aluminium; • introducing the powders mixture into the melted metal or alloy; • production of composite cast. The technological process variants enable: • production of the structure AMCs cast with reinforcement of the given phase composition and the assumed dispersive structure were obtained; • production by the casting method of the composite semifinished product for the structure of the used casting alloys modification; • application of composite semi-finished product for the centrifugal casting process of the aluminium matrix composite alloys [30]. Only the chosen results of research upon the production of Al–FeAl–TiAl–Al2 O3 cast composites with hybrid reinforcement have been presented in this article.

37

Acknowledgment The research was financed within the project of Polish State Committee for Scientific Research (KBN) (contract no. PBZ-KBN-041/T08/08-10).

References [1] M.D. Huda, M.S.J. Hashim, M.A. El-Baradie, MMCs: materials, manufacturing and mechanical properties, Key Eng. Mater. 104–107 (1995) 37–64. [2] M. Gupta, M.K. Surappa, Processing, microstructure and mechanical properties of Al base metal matrix composites synthesis using casting route, Rew. Eng. Mater. 104–107 (1) (1995) 259–274. [3] A. Mortensen, Metal matrix composites in industry: an overview, in: MMC ASSESS Final Presentations during MMC VIII conference, London, 2001, http://www.simx.epfl.ch/simx/. [4] J. Hashim, L. Looney, M.S.J. Hashim, Metal matrix composites: production by the stir casting method, J. Mater. Process. Technol. 92–93 (1999) 1–7. [5] D.M. Skibo, D.M. Schuster, L. Jolla, Process for preparation of composite materials containing nonmetallic particles in a metallic matrix, and composite materials made by, US Patent 4,786,467 (1988). [6] A.M. Samuel, F.M. Samuel:, Foundry aspects of particulate reinforcement aluminium MMCs: factors containing composites quality, Eng. Mater. 104–107 (1995) 65–98. ´ [7] J. Sleziona, Forming of the properties Al. Alloys-ceramic particles production by the foundry methods, ZN. 47, Silesian University of Technology, Gliwice, 1994 (in Polish). ´ [8] A. Posmyk, J. Sleziona, A. Grosz, J. Wieczorek, Reibungs – und Schmierungsverthalten von Aluminium – legierungen mit einem verst¨arkten Oberfl¨achenbereich, Technische Akademie Esslingen, in: Proceedings of the 12th International Collo␳uium, January 11–13, Tribology, 2000, Plus. ´ [9] J. Wieczorek, A. Dolata-Grosz, M. Dyzia, J. Sleziona, Tribological properties of metal matrix composites (AK12) reinforced with ceramic particles, Kompozyty (Composites) 1 (2) (2001) 207–210 (in Polish). ´ [10] J. Myalski, J. Sleziona, A. Dolata-Grosz, A. Posmyk, Tribological properties of Al matrix composites reinforced with SiC and Al2 O3 ceramic particles, in: Proceedings of the Materials Week, Advanced Materials and Technology, Munich, 2001. [11] F. Delannay, L. Froyen, A. Deruyttere, The wetting of solids by molten metals and its relation to the preparation of metal-matrix composites, J. Mater. Sci. 22 (1987) 1–16. ´ [12] A. Sleziona, A. Grosz, J. Dytkowicz, Wieczorek, The effect of Al2 O3 and SiC particles preparation on quality of the metal-ceramic suspension, in: Proceedings of the IV International Conference, Surface Phenomena in Foundry Processes, Pozna´n – Kołobrzeg, 1998, pp. 263–271 (in Polish). [13] J. Eliasson, R. Sandstr¨om, Applications of aluminium matrix composites, Key Eng. Mater. 104–107 (1995) 3–36. [14] L. Froyen, In situ processing of MMCs, an overview, in: Proceedings of the Int. Conf. on Light Metals and Composites, Zakopane, 1999, p. 15. [15] L. Froyen, In situ processing of MMCs and of the wetting problems? Transactions of Japan Welding Research Institute, 30 (2001) Special Issue, Proceedings of HTC-2000. [16] E. Fra´s, A. Janas, A. Kolbus, M. G´orny, Synthesis of the in situ Al–TiC and Cu–TiC composites by using the reactive gas, In˙zynieria Materiałowa (2) (2000) 48–55 (in Polish). [17] E. Fra´s, A. Jonas, S. Wierzbi´nski, A. Kolbus, Synthesises of aluminium composites reinforced with titanium carbides particles, in: Proceedings of the Int. Conf. on Light Metals and Composites, Zakopane, 1999, p. 323.

38

A. Dolata-Grosz et al. / Journal of Materials Processing Technology 162–163 (2005) 33–38

[18] P.C. Maity, P.N. Chakraborty, S.C. Panigrahi, Al-Al2 O3 in situ particle composites by reaction of CuO particles in molten pure Al, Mater. Lett. 30 (1997) 147–151. ´ [19] M. Dyzia, J. Sleziona, A. Dolata-Grosz, J. Wieczorek, Application of Al–FeOTiO2 System to the Preparing of In-situ Aluminium Composites Reinforced with Ceramic and Intermetalic Phases, Junior Euromat 2002, Lozanna. [20] A. Zyska, K.N. Braszczy´nska-Malik, Structure of the Al(TiB2 + Al2 O3 )p composites produced by in situ method, Kompozyty (Composites) 4 (11) (2004) 336–340 (in Polish). [21] F. Barbbier, M.H. Ambroise, In situ process for producing aluminum matrix composites containing intermetallic materials, J. Mater. Sci. Lett. 14 (1995) 457–459. [22] R.M. Aikin Jr., The mechanical properties of in situ composities, JOM 49 (8) (1997) 35–39. [23] B. Formanek, A. Maciejny, K. Szopi´nski, A. Olsz´owka-Myalska, Composites powder materials obtained by mechanical alloing process, In˙zynieria Materiałowa 3-4 (1999) 137–143 (in Polish). [24] B. Formanek, A. Gierek, K. Szopi´nski, Dispersion hardened Al–Me–SiC powders obtained by the mechanical alloying method, AMT’98 Krynica, In˙zynieria Materiałowa 4 (1998) (in Polish). ´ [25] A. Dolata- Grosz, J. Sleziona, J. Wieczorek, B. Formanek, Properties of Al matrix composites reinforced with fine dispersed SiC and

[26]

[27]

[28]

[29]

[30]

[31]

Al2 O3 particles, in: Proceedings of the Int. Congress on Advanced Materials and Technology, Materials Week, Munich, 2001. ´ A. Dolata- Grosz, J. Sleziona, B. Formanek, Structure and properties of aluminium cast composites strengthened by dispersion phases, in: Proceedings of the 12th Int. Sci. Conf. on Achievement in Mechanical and Materials Engineering, AMME, Zakopane, 2003, pp. 301–306. B. Formanek, K. Szyma´nski, B. Szczucka-Lasota, Composite powders from an intermetallic Fe–Ti–Al alloy with aluminium oxide, Kompozyty (Composites) 3 (8) (2003) 407–414 (in Polish). B. Formanek, A. Maciejny, K. Szyma´nski, J. Szala, L. Paj˛ak, R. Przeliorz, High temperature synthesis-SHS of Composites powders containing iron and titanium aluminides and aluminium oxide – synthesis conditions and structure of powders, In˙zynieria Materiałowa 3-4 (1999) 150–158 (in Polish). ´ A. Dolata-Grosz, B. Formanek, J. Sleziona, J. Wieczorek, Aluminium hybrid composites reinforced with intermetallic and ceramic phases, Arch. Foundry 4 (14) (2004) 126–131. ´ A. Dolata-Grosz, J. Sleziona, B. Formanek, Aluminium matrix cast composite (AMCC) with hybrid reinforcement, Arch. Foundry, PAN, 5 (15) (2005) (in polish) in press. N.J. Welham, Mechanochemical reaction between ilmenite (FeTiO3 ) and aluminium, J. Alloys Compd. 270 (1998) 228–236.