A novel high-performance Al-6Zn-4Ni-2Mg-1Cu-Fe alloy for wire-arc directed energy deposition

Directed energy deposition processes are increasingly incorporated in modern industrial manufacturing chains. Aluminum alloys often fall short either of mechanical properties, or of processability. Therefore, the need for new alloy compositions emerges that show both robust and versatile processability as well as high mechanical performance. Here, an alloy composition that has not been tested yet for directed energy deposition is investigated: Al-6Zn-4Ni-2Mg-1Cu-Fe. To achieve the required properties, the positive effects of intermetallic phases forming during solidification and subsequent heat treatment are jointly utilized in this alloy system. After wire fabrication and processing by directed energy deposition, the specimens were characterized in detail and the effects of a post-process heat treatment were assessed. Characterization results evidence the absence of crystallographic texture and the presence of various intermetallic phases in combination with high mechanical strength values: 485 MPa yield strength and 545 MPa ultimate tensile strength after a solution heat treatment followed by an artificial aging heat treatment. The systematic investigations of a new high-performance aluminum alloy shed light upon the complex microstructures in as-built and heat-treated material conditions and their relevance to mechanical properties.