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The development of new metal matrix composites for lightweight applications is aiming for an increase in specific strength and stiffness compared to conventional light metal alloys. The composite extrusion process is a promising manufacturing method for continuously reinforced light metal profiles. Especially the reinforcement with ceramic fibers leads to an increase in the specific strength and stiffness. For these investigations a hybrid composite is produced by using an Al 2 O 3 -fiber/AlMg0.2 composite wire which is embedded in an EN AW-6082 aluminum matrix. It is shown that the mechanical properties of the composite exceed those of the unreinforced matrix material. An explicit investigation of the deformation and damage behavior of this composite is given by optical strain analysis and in situ tensile tests in an X-ray micro computed tomograph (m-CT). It was observed that during tensile loading multiple fracture of the composite wire occurs while exceeding the strain limit of the non-embedded composite wire. It could be shown that fracture of the composite wire is accompanied by strain localization and therefore strain hardening occurs in vicinity of the internal fracture, which leads to multiple necking of the specimen. The m-CT analysis reveals the intrinsic damage mechanisms and shows the beginning of ceramic fiber fracture which showed evidence for a local load distribution between the fibers resulting in a planar fracture of the composite wire. The multiple fracture of the wire allows for an interface shear strength analysis and indicates a good bonding of the composite wire.

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Composite extruded, unidirectionally spring steel wire reinforced profiles have great potential for lightweight applications. Joining of these profiles represents a difficult challenge due to the different material properties, which eliminate fusion welding as a possible joining method. Friction stir welding (FSW) has recently been used to join these profiles, the disadvantage of which is that the reinforcement elements may be bent and fragmented during welding leading to drastically reduced mechanical properties compared to non-joined profiles and even to the unreinforced matrix material. In order to minimize the disturbing influences of the reinforcement elements on the joining strength, the weld axis was shifted to the retreating side, reducing wire-pin contact at the advancing side. As a second remedial measure an insert made of matrix material was placed between the joining partners before joining in order to reduce the contact on both sides. In-situ tensile tests within an X-ray micro computed tomograph (µCT) showed that shifting the weld axis could not improve the joint quality significantly. However, the use of an insert improves the offset yield strength (Rp0.2) by about 50 %.