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Since its first synthesis in 2004 graphene was characterized intensively and exceptional properties in terms of e.g. mechanical strength, stiffness and electrical as well as thermal conductivity were revealed. These properties make graphene very attractive to be applied as additive in composite materials e.g. to increase strength and conductivity compared to the pure matrix material. In this study graphene nano platelets (GNP) in contents of 0. 5%, 1.0 % and 1.5 % were added to pure (99.7 %) aluminum powder and dispersed via EIRICH mixer method. This method is very appealing since homogenous mixtures can be achieved in significantly lower time when compared to e.g. the ball milling process. After subsequent cold compaction the composite materials were extruded with three different extrusion ratios. The influence of GNP content and extrusion ratio on the specific extrusion pressure is characterized as well the resulting rod surface quality, respectively. The effects of GNP content and extrusion ratio on homogeneity of graphene dispersion in the aluminum matrix, the relative density of the composite as well as hardness were also investigated.

In this work the extrusion of tailored aluminum tubes is investigated. Therefore, a stepped mandrel was applied and moved in axial direction in order to vary the tube’s wall thickness. Since surface irregularities were observed on the tube’s surface in transition areas between the different wall thicknesses, the material flow was analyzed by FEM in order to clarify the origin of the surface defects. It was revealed that the inwardly directed material flow in combination with the lack of inward resistance when the mandrel step is moving in the region of the die bearing causes the geometric inhomogenities.

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