Intrinsic Heat Treatment of an Additively Manufactured Medium Entropy AlCrFe2Ni2-Alloy

The alloy AlCrFe2Ni2, known as medium entropy alloy (MEA, ∆S/R 1.33) was processed using Laser Direct Energy Deposition (L-DED). The alloy is designed to develop a Widmanstätten type duplex microstructure following a solid state phase transformation which is controlled by the cooling rate. During L-DED this transformation is hardly accomplished, commonly calling for a post-build heat treatment. For the first time, an intrinsic laser-based heat treatment was applied to promote this phase transformation in the Additively Manufactured HEA in a layer by layer approach. Process parameters for the intrinsic heat treatment were varied and investigated in terms of temperature–time cycles, cooling rates and penetration depth. The microstructure of as-built and differently heat-treated samples was investigated. In the as-built condition, the duplex structure consist mainly of ordered and disordered bcc phase and a small fraction of thin fcc-plates (40