Obtaining of AMCs in combined casting and powder metallurgy processes
Anna Dolata-Grosz*, Bolesław Formanek**, Józef Śleziona** *Politechnika Śląska, Wydział Inżynierii Materiałowej i Metalurgii, Katedra Technologii Stopów Metali i Kompozytów, ul. Krasińskiego 8, 40-019 Katowice ** Politechnika Śląska, Wydział Inżynierii Materiałowej i Metalurgii, Katedra Nauki o Materiałach, ul. Krasińskiego 8, 40-019 Katowice
Quarterly No. 1, 2006 pages 8-14
DOI:
keywords: cast composites, composite powders, in situ composites, aluminium alloys
abstract Aluminium matrix composites (AMCs) have found applications in the aerospace, military, and especially in the automotive industries. The literature review showed that the most of studies were concentrated on an aluminium matrix composites with SiC and Al2O3 hard particles reinforcement. During recent years, the articles appeared concerning capability fabricate and employment of other, dispersion reinforcing particles like: TiC, ZrC, B4C, Cr3C2 or TiB2 and intermetallic phases. The basic technologies used for manufacturing of these in situ composites are powder metallurgy methods (P/M) and casting techniques. These composites 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. This paper presents the material and technological concepts related to obtaining selected multiphase aluminium composites produced in combined casting and powder metallurgy processes and their structures. The structure of aluminium alloys was modified with composite powder mixtures which in a reaction with aluminium reinforced the matrix with intermetallic and ceramic phases. As a carrier of reinforcing phases, reactive composite powders were used, obtained in a self-propagating high-temperature synthesis (SHS). The morphology and phase composition of the powders applied are shown in Figures 1-4. By applying a casting method (mechanical stirring), composites with heterophase reinforcement were fabricated, in complex reactive systems: Al/FeAl-TiAl-Al2O3, Al/FeAl3-TiC-Al2O3, Al/NiCr-Cr3C2-TiC and Al/Fe(Cu)-TiC. The structure of the composites was characterized by means of light and scanning microscopy methods, and the phase and chemical compositions of the reinforcement were identified by diffraction and X-ray spectroscopy methods. The examination results are presented in Figures 5-8. The casts obtained were characterized by complex phase structures of different morphologies and chemical compositions. The research carried out has shown that a combination of casting and introducing a composite powder of a defined chemical composition is an effective process which enables the production of hybrid composites of defined multiphase reinforcement and a dispersion structure.