Changing the alloy composition of Al7075 for better processability by selective laser melting

Selective Laser Melting (SLM) of conventional aluminium alloys has mainly been restricted to casting alloys, such as AlSi10Mg and AlSi12. Despite the challenges of processing aluminium alloys via SLM, like the high reflectivity, high conductivity and its reactivity with oxygen, these alloys are relatively easy to process with Additive Manufacturing (AM) because they are optimized to be processed via the melt. In this research, SLM of Al7075, a strong wrought alloy, is shown to lead to suboptimal density and microcracking. The alloy was tailored by adding 4% Silicon which increased the density to 99%. Moreover, the microcracks were significantly reduced by the grain refining effect caused by the addition of silicon. In addition, the hardness of the SLM processed Si-added Al7075 alloy can be improved by proper heat treatments. As such, this work provides new insights for producing high strength aluminium alloys by AM.