Microstructural characterization of MAR-M247 fabricated through scanning laser epitaxy

Nickel-base superalloys are extensively used to produce gas turbine hot section components as these alloys offer improved creep strength and higher fatigue resistance compared to other alloys due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al (γ' phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, we demonstrate powder bed fusion-based additive manufacturing of MAR-M247 onto like-chemistry substrates through scanning laser epitaxy (SLE). The SLE deposited MAR-M247 followed the polycrystalline morphology of the underlying MAR-M247 substrate. Metallurgical continuity was achieved across the entire deposit-substrate interface and the samples showed no warpage during the laser processing across a broad range of processing parameters. Optical imaging, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) were carried out to characterize the microstructural refinement in the SLE fabricated MAR-M247. This work is sponsored by the Office of Naval Research through grants N00014-11-1-0670 and N00014-14-1-0658.