Effects of doping technologies on mechanical properties and microstructures of RExOy doped molybdenum alloys

Mo-La alloy powders were all prepared by a novel nanoparticle spray doping technology and a conventional solid-liquid spraying technology respectively. Mo-La alloy powders were fabricated into 1.8 mm-diameter wires by powder metallurgy and thermomechanical processing. The mechanical properties of these wires were determined at room temperature and 1773 K, their microstructures observed by transmission electron microscope (TEM). The results show that with the same addition of doped elements, the comprehensive mechanical properties of Mo-La alloy synthesized by the nanosized powder spray doping technology were about 50% higher than those of the conventional solid-liquid doping process. The results attribute to the reason that the nanoparticle spray doping technology is liable to provide much more La2O3 particles compared with the conventional solid-liquid doping process, and that the particles, whose sizes are three orders smaller than that of the solid-liquid doping process, are much more homogeneously distributed in the intragranular and intergranular molybdenum substrates. The excellent dispersion strengthening effects of the novel doping technology were quantitatively analyzed by Fisher theory.