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Ever-increasing demands of industrial manufacturing regarding mechanical properties require the development of novel alloys designed towards the respective manufacturing process. Here, we consider wire arc additive manufacturing. To this end, Al alloys with additions of Zn, Mg and Cu have been designed considering the requirements of good mechanical properties and limited hot cracking susceptibility. The samples were produced using the cold metal transfer pulse advanced (CMT-PADV) technique, known for its ability to produce lower porosity parts with smaller grain size. After material simulations to determine the optimal heat treatment, the samples were solution heat treated, quenched and aged to enhance their mechanical performance. Chemical analysis, mechanical properties and microstructure evolution were evaluated using optical light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence analysis and X-ray radiography, as well as tensile, fatigue and hardness tests. The objective of this research was to evaluate in detail the mechanical properties and microstructure of the newly designed high-performance Al–Zn-based alloy before and after ageing heat treatment. The only defects found in the parts built under optimised conditions were small dispersed porosities, without any visible cracks or lack of fusion. Furthermore, the mechanical properties are superior to those of commercial 7xxx alloys and remarkably independent of the testing direction (parallel or perpendicular to the deposit beads). The presented analyses are very promising regarding additive manufacturing of high-strength aluminium alloys.

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Three hypoeutectic Fe containing Al–Si–Mg alloys for casting crash relevant automotive components are experimentally investigated. The comparatively short heat treatments include solutionising at 540°C for 5 min or at 465°C for 60 min respectively, compressed air quenching and artificial aging at 223°C for 120 min. Characteristic mechanical parameters are determined by tensile, plate bending and Charpy pendulum impact tests. Intermetallic phases are identified by scanning electron and by light microscopy. The results show that increasing the Mg content promotes the precipitation of Mg2Si particles, which enhance the strength. Increasing the Fe content promotes the formation of intermetallic Fe bearing particles which reduce the energy absorption capacity and the ductility. Increasing the Si content has the similar effect, since the volume fraction of the eutectic phase and the size of the intermetallic particles increase.