High-Throughput Alloy Screening by Means of In Situ Alloying with Multi-wire DED-LB Nozzle COAXquattro

In situ alloying through laser direct energy deposition (DED-LB) is an innovative technique that enables the design of complex metal alloys with tailored properties directly during the additive manufacturing process. The coaxial high-power multi-wire laser cladding head COAXquattro developed at Fraunhofer IWS enables in situ alloying from a variety of wire and powder combinations during the deposition process. In this work, novel compositionally complex alloys were produced by in situ mixing of commercially available stainless steel 316L and Inconel 625 (IN625) wires at different ratios. Additions of small amounts of molybdenum, titanium, and aluminum powders were used to enhance the corrosion resistance and mechanical strength of designed alloys. In situ alloyed NiFeCr-based laser tracks exhibited a microstructure with face-centered cubic matrix and segregations of niobium. The phase structure of the specimens has been compared to the results of preliminary CALPHAD calculations executed with Thermo-Calc software using TCFE13 and TCNI12 databases, showing a good agreement between calculations and experimental results. Potentiodynamic polarization tests revealed better corrosion resistance performance of in situ generated alloys compared to 316L stainless steel.