MATERIALE PLASTICE ♦53♦No.3♦2016 http://www.revmaterialeplastice.ro 428 Thermodinamics of in situ Production of Aluminium Matrix Composites Comparative analysis MIHAI BUTU 1 , PETRU MOLDOVAN 1 , FLORIN DRAGOS MARCU 1 *, ANDREI BERBECARU 1 , CONSTANTIN DOMENIC STANCEL 1 , LUCIAN ROSU 1 , IONEL UNGUREANU 2 1 University Politehnica of Bucharest, Materials Science and Engineering Faculty, 313 Splaiul Independetei, 060042, Bucharest, Romania 2 ALRO S.A., 116 Pitesti Str., 230048, Slatina, Romania The aim of this work is to examine the role of alloying elements (Cu, Mg, Zn) in the complex reactions occurring in the heterogeneous system Al-Cu-Mg-Zn/K 2 TiF 6 /KBF 4 at high temperatures. The paper presents theoretical and experimental studies to obtain aluminothermic reactions of composite AA7xxx/TiB 2 , putting into evidence the thermodynamic calculations and X-ray diffraction resulting compounds. Keywords: Al-Cu-Mg-Zn, TiB 2 , aluminium matrix composites, XRD Fig. 1. Phase diagram Al–Cu–Mg–Zn: (a) polythermal diagram, (b) distribution of phase fields in the solid state in the aluminum corner, and (c) single-phase domains [1] * email: dragosmarcu@yahoo.com Metal matrix composites (MMC) proved to be a class of materials with the potential to replace a large number of materials used in automotive industry, aerospace, electronics, defence and in the manufacture of sports equipment, where the requirement for lightweight parts with high strength is increasing. Alloys from the quaternary system Al-Cu-Mg-Zn displays outstanding properties both as cast and after machining and specific heat. However this system is not sufficiently studied, although it is used in high-tech industries, especially because of the large main alloying elements. However, the fundamental understanding of the (Al) corner of this diagram, in particular, the liquidus projections and solidification surface are absent. For this reason, figure 1 represents the results obtained by the authors [1] based on many years of joint work upon this subject. Table 1 provides the corresponding non-variant phase reactions. One should mention that the latter take place at concentrations, which are quite different from those corresponding to known industrial alloys. For this reason the most valuable information is contained in the isothermal cross-sections provided in figure 1. An important peculiarity of this phase diagram is that the three phases of the Al-Mg-Zn system and the three phases of the Al-Cu-Mg system form continuous solid solutions. It is important that in the Al-Cu-Mg system, the CuMgAl and Cu 6 Al 2 Mg 7 compounds are not in equilibrium with (Al) and additions of zinc are required so that these equilibria could take place. There are three domains corresponding to continuous solid solution formed by the phases CuMg 4 Al 6 and Mg 3 Zn 3 Al 2 , MgZn 2 and CuMgAl, and Cu 6 Mg 2 Al 5 and Mg 2 Zn 11 . The CuMg 4 Al 6 and Mg 3 Zn 3 Al 2 phases in ternary systems exist in a broad range of concentrations. In the quaternary system the phase domain occupied by the quaternary solid solution (the T-phase - cubic structure) is also quite broad (fig.1). The quaternary solid solution between compounds