Abstract

Additive manufacturing (AM) is a layer by layer process that has the potential to disrupt traditional fabrication methods. It allows fast manufacturing of three dimensional pieces from metallic powders, with great exibility of design, potential for weight reduction, fast

production speed for complex parts, and shorter lead times. However, at the moment, there is only a reduced range of materials that can be industrially processed using AM.

High strength aluminum alloys have great importance in the aerospace sector and they are used to build multiple components of aircrafts. These aluminum alloys present

poor results when additively manufactured, exhibiting high porosity and an undesired microstructure formed by large columnar grains surrounded by longitudinal cracks.

In this work, high strength 7075 aluminum alloy powders were mixed with zirconium(II) hydride particles in order to reduce the cracking density during selective laser melting. Samples were produced with a 95% density, both with and without particles. The addition of Zr led to crack reduction, attributed to enhanced nucleation at Al-Zr precipitates, as well as to equiaxed, ultra ne grains. A random texture developed along the building direction. Al-Cu precipitates were also found at grain boundaries, probably contributing to pinning of the

latter. A hardness increase of 30 HV was observed in the alloy with ZrH2 particles added probably due to the hardening effect of an enhanced precipitate volume fraction as well as to the contribution of fi ne grains.