Alloy design of feedstock material for additive manufacturing: exploring the Al-Co-Cr-Fe-Ni-Ti compositionally complex alloys

The need for sustainable use of resources requires continuous improvement in energy efficiency and the development of new approaches to the design and processing of suitable materials. The concept of high entropy alloys (HEAs) has been recently extended to more general compositional complex alloys and multi-principal element alloys. One of the major challenges on the way to application of these alloys is the extensive design and selection efforts due to the great variety of possible compositions and its consequences for workability and resulting material properties. The favorable high-temperature strength of Ni-based and Co-based superalloys is ascribed to a defined gamma/gamma’ structure consisting of a disordered fcc matrix and ordered L12 precipitates. In the current work we extended this design concept, allowing, disordered bcc A2 and ordered B2 phases in additions or in substitution of the original gamma/gamma’ structure. A high-throughput screening approach was used combining CALPHAD-based computational tools with in situ alloying by means of laser cladding. Wall specimens with gradient composition in the system Al-Co-Cr-Fe-Ni-Ti with varying Al, Ti and Cr content were analyzed. The combined modelling and experimental screening approach was demonstrated to be a powerful tool for designing new high performance AM-ready feedstock.