Influence of processing on the microstructure of nickel aluminum bronze (NAB)

Nickel-aluminum bronze (NAB) alloys are commonly used for marine applications such as propellers by the U.S. Navy. These NAB components conventionally manufactured using casting techniques, but recent interest has shifted to possibility of additive manufacturing (AM) processes. The following literature review discusses microstructural evolution (nominally) Cu-9Al-5Ni-5Fe-1Mn in cast, wrought, friction stir processed, arc-welded, electron beam welded and laser-welded conditions. exhibit a complex microstructure, consisting mixture five κ precipitates distributed an α or β’ martensitic matrix. size, morphology, distribution these phases sensitive changes cooling rate thermal history those imposed AM welding. Although microstructure is well documented under conditions, no continuous diagrams have been developed describe phase transformations arc laser processing conditions NAB. As such, this investigates reports related arc, laser-based processes associated microstructures properties. Studies reported additively with improved properties compared cast material, differences microstructure. At moderate rates, arc-based processing, consists Widmanstätten various phases, which become more refined increasing rate. This leads improvement tensile wire-arc direct energy deposited NAB, > 17% increase yield strength 90% ductility when material. rapid rates representative primarily twin-related martensite nanoscale phases. significant (>60–100%) at expense (<−30%) Additionally, previous studies that from high corrosion resistance There also evidence conventional heat treatments need be optimized materials. report includes methods challenges characterizing provides recommendations future research.