Aluminium alloys produced by additive manufacturing are largely used in aerospace and aeronautical fields where damage may occur due to overloads experienced in service. A promising solution to avoid the replacement of damaged parts by new ones is to use a material able to heal its damage sites. The aim of this research is to develop a new high-strength healable Al alloy manufactured by Laser Powder Bed Fusion (LPBF). Thanks to LPBF and its high cooling rate, a very thin microstructure consisting of α-Al cells enclosed by a Mg-rich low melting point eutectic network acting as healing agent is obtained, similarly to biological vascular systems. After damage, a healing heat treatment (HHT) induces the melting of this healing agent eutectic phase which can flow inside the defects to seal and weld them upon solidification. In order to obtain a high-strength healable Al alloy, Zr is dispersed into this Al-Mg alloy and forms hardening precipitates. In this work, the static mechanical properties of this new Al-Mg-Zr alloy called Almazium have been characterised in the as-built state as well as after different HHT where the temperatures and times vary. In the optimal printing conditions, it appeared that the addition of Zr increased the yield strength from 150 MPa up to 408 MPa in average for as-built samples. The influence of the LPBF parameters on the strength of Almazium will be characterized and explained thanks to chemical composition analysis and optical and electronic microscopy techniques. The temperature and the time of the HHT will be optimised to avoid a too large coarsening of hardening precipitates detrimental for mechanical properties. Finally, the damage healing ability of Almazium has been assessed thanks to in-situ damage-healing cycles during synchrotron X-ray nano-tomography experiment at beamline ID16B at the ESRF. It allows the observation of the damage mechanism, the local healing, and if the healed damage sites are source of new damage initiation during new overloading.
Raedemacker et al. (Wed,) studied this question.