Consolidation and mechanical properties of mechanically alloyed Al-Mg powders
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1128-U05-46
Consolidation and mechanical properties of mechanically alloyed Al-Mg powders Mira Sakaliyska1, Sergio Scudino1, Hoang Viet Nguyen2, Kumar Babu Surreddi1, Birgit Bartusch1, Fahad Ali1, Ji-Soon Kim2 and Jürgen Eckert1,3 1 IFW Dresden, Institut für Komplexe Materialien, Postfach 270116, D-01171 Dresden, Germany 2 Research Center for Machine Parts and Materials Processing, University of Ulsan, Namgu Mugeo 2-Dong, San 29, Ulsan 680-749, Republic of Korea 3 TU Dresden, Institut für Werkstoffwissenschaft, D-01062 Dresden, Germany. ABSTRACT Nanostructured Al-Mg bulk samples with compositions in the range of 10 – 40 at.% Mg have been produced by consolidation of mechanical alloyed powders. Powders with composition Al90Mg10 and Al80Mg20 were consolidated into highly dense specimens by hot extrusion. Room temperature compression tests for the Al90Mg10 specimen reveal interesting mechanical properties, namely, a high strength of 630 MPa combined with a plastic strain of about 4 %. The increase of the Mg content to 20 at.% increases the strength by about 100 MPa but it suppresses plastic deformation. The Al60Mg40 powder was consolidated at different temperatures by spark plasma sintering and the effect of the sintering temperature on microstructure, density and hardness have been studied. The results reveal that both density and hardness of the consolidated samples increase with increasing sintering temperature, while retaining a nanocrystalline structure. These results indicate that powder metallurgy is a suitable processing route for the production of nanocrystalline Al-Mg alloys with promising mechanical properties. INTRODUCTION In recent years, nanostructured materials have been attracting much attention due to their scientific and engineering significance [1-3]. In particular, substantial increase in strength has been observed in a number of alloys with nanoscale microstructures [3,4]. Among the different processing routes, solid-state processing such as mechanical alloying (MA) have gained increasing interest as versatile non-equilibrium techniques for the production of metastable materials including amorphous alloys, quasicrystalline and nanocrystalline alloys [5-8]. However, materials in powder form, such as milled powders, have to be consolidated to achieve dense bulk specimens [4]. Consolidation of nanocrystalline powders into fully dense bulk specimen is thus of primary interest in the development of near-net shape parts for technological applications [4]. The essence of all compaction techniques is to apply high pressure for densification, and rather high temperature to soften the material so that plastic deformation allows better filling and material flow by diffusion helps to remove the remaining porosity [4]. However, the consolidation of nanocrystalline powders is a very complex procedure and the operational conditions, e.g. pressure, temperature and holding time during the powder consolidation process, are difficult to control precisely in order to obtain fully dense specimens with complete bonding
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