Structure and Properties of Heat-Resistant Alloys NiAl-Cr-Co-X (X = La, Mo, Zr, Ta, Re) and Fabrication of Powders for Additive Manufacturing

The NiAl-Cr-Co-X alloys were produced by centrifugal self-propagating high-temperature synthesis (SHS) casting. The effects of dopants X = La, Mo, Zr, Ta, and Re on combustion, as well as the phase composition, structure, and properties of the resulting cast alloys, have been studied. The greatest improvement in overall properties was achieved when the alloys were co-doped with 15% Mo and 1.5% Re. By forming a ductile matrix, molybdenum enhanced strength characteristics up to the values sigma(ucs) = 1604 +/- 80 MPa, sigma(ys) = 1520 +/- 80 MPa, and epsilon(pd) = 0.79%, while annealing at T = 1250 celcius and t = 180 min improved strength characteristics to the following level: sigma(ucs) = 1800 +/- 80 MPa, sigma(ys) = 1670 +/- 80 MPa, and epsilon(pd) = 1.58%. Rhenium modified the structure of the alloy and further improved its properties. The mechanical properties of the NiAl, ZrNi5, Ni0.92Ta0.08, (Al,Ta)Ni-3, and Al(Re,Ni)(3) phases were determined by nanoindentation. The three-level hierarchical structure of the NiAl-Cr-Co+15%Mo alloy was identified. The optimal plasma treatment regime was identified, and narrow-fraction powders (fraction 8-27 mu m) characterized by 95% degree of spheroidization and the content of nanosized fraction <5% were obtained.

Automated summary

The production and properties of NiAl-Cr-Co-X alloys were studied. Co-doping with Mo and Re significantly improved overall properties, enhancing strength characteristics by forming a ductile matrix. Mo increased strength, while Re modified the structure and further improved properties.