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Three different approaches to control the phase formation in powder bed fusion - laser beam (PBF-LB) printing using a powder mixture of duplex stainless steel (DSS) 2507 and austenitic stainless steel 316 L were examined: (i) in situ solid state reheating, (ii) utilization of an island scan strategy, and (iii) switching process parameters between layers of a build. Analytical modeling was used to determine the time-temperature profiles during each of these processes, and was combined with thermodynamic simulations through Thermo-Calc to predict and explain the phase formation measured experimentally. It was found that the reheating from additional layers was critical to the nucleation of austenite, even with the increased Ni content in powder mixtures. This was evident in the island scan strategy prints where the corners of the islands showed significantly less austenite (∼45%) as compared to the centers of the …