Advanced Engineering Materials

For the first time the ultrasonic metal welding technique is applied successfully to join sheet metals with CFRP. Different aluminum alloys are studied and mechanically characterized. Tensile shear strengths of up to 58 MPa are achieved. The microstructure of the hybrid joints are investigated by electron microscopy. Besides single spot welded Al/CFRP-joints also multi-spot welded structures are realized.

CuZr₂ (MoSi₂ type) phase structure is analyzed using clusters centered by two non-equivalent atomic sites: small sphere Cu and large sphere Zr. It is shown that the clusters are all shared atoms in different ways with their neighboring clusters, so after sharing effective cluster should be put out to describe the alloy phase.

In the current study, titanium spinal implants with a gradient in porosity were produced by combining the 2-Component-Metal Injection Moulding technique with the space holder method. Net-shape production was accomplished using feedstocks with and without space holder particles, in a fully automated injection process. The gradient in porosity is attractive for biomedical implants, as it combines low porous parts with high mechanical strength with highly porous parts, which promote a stable interlock between bone tissue and implant.

Repeatable auxetic foams are produced using three-dimensional printing technologies. This methodology is applied here for the first time to produce playable polymeric auxetic foams with an idealized re-entrant cellular structure. During uniaxial tensile stress, the foams show negative Poisson's ratios as low as −1.18. The experimental Poisson's ratios of the auxetic foams are compared against the data predicted by a three-dimensional mathematical model.