The effect of processing parameter on zirconium modified Al-Cu-Mg alloys fabricated by selective laser melting

The newly designed alloy compositions for selective laser melting (SLM) have aroused great interest. In this study, zirconium modified Al-Cu-Mg alloys were fabricated by SLM. Results show that crack-free samples with relative density of nearly 100% were obtained by optimizing the processing parameters. With the increase of scanning speed, the relative density decreases due to insufficient energy input. In addition, the microstructure transforms from homogeneous to bio-modal, the reason is the unstable flows caused by the high scanning speed. The small hatching space will provide more energy input and preheat, leading to the coarse surface. Introduction Additive Manufacturing (AM) processes enable to fabricate parts with very complex shape[1]. Selective laser melting (SLM), one of the preferred AM techniques, has recently gained considerable attention due to high manufacturing flexibility, nearnet-shape production and efficient use of raw material[2, 3]. Al-Cu-Mg alloy has become an attractive material due to the low density, high fracture toughness and fatigue strength[4, 5]. Nowadays, processing high strength aluminum alloys by SLM is confronted with great difficulties because of its poor flowability, high reflectivity, high thermal conductivity, large solidification range and hot cracking susceptibility[6]. Therefore, the biggest stumbling block to the application of high strength aluminum in SLM is the hot crack. To expand the scope of aluminum alloys suiting for SLM, new high strength aluminum alloys are urgent to be investigated. Recently, scandium (Sc), zirconium (Zr), titanium (Ti) and vanadium (V) have been proved as the effective microalloying element for aluminum alloys to improve the weldability and mechanical properties[7-9]. Nowadays, the addition of microalloying element has been applied to SLM aluminum alloys to improve their formability. The microstructural evolution, densification, properties and heat treatment of Al-Mg-Sc-Zr fabricated by SLM have been investigated[10-13]. Zhang H et al.[14] have found that the Zr modified Al-Cu-Mg parts with ultrafine grain exhibits better mechanical properties and broader processing window. However, the effect of processing parameters on the Zr modified Al-Cu-Mg alloy has not been studied. 1246 Solid Freeform Fabrication 2018: Proceedings of the 29th Annual International Solid Freeform Fabrication Symposium – An Additive Manufacturing Conference Reviewed Paper