Preparation and sintering properties of nanometer W−30Cu−La₂O₃ powders

Tungsten copper oxide precursor powders were prepared by low temperature self-propagation method with tungstic acid, copper nitrate, and cerium nitrate hexahydrate as the raw materials, glycine as the fuel, ammonium nitrate as the accelerant. Nanometer W–30Cu–La₂O₃ composite powders were obtained by hydrogen reduction, and the W–30Cu–La₂O₃ alloys were prepared by sintering in hydrogen atmosphere. The effects of molar ratios of tungstate with glycine and ammonium nitrate on phase, morphology, and properties of the precursor powders and the reduced composite powders were investigated. The relative density, microstructure, and comprehensive properties of the W–30Cu–La₂O₃ alloys at different sintering temperatures were analyzed. The results show that the optimal molar ratio of tungstic acid with glycine and ammonium nitrate is 1:10 and 1:25, respectively. The powders have good uniformity, the specific surface area is 6.6271 m²·g⁻¹, and the powder size is 100～200 nm. The optimal sintering temperature is 1350 ℃. The relative density, bending strength, Vickers hardness, and thermal expansion coefficient of the alloys sintered at 1350 ℃ is 99.0%, 1205 MPa, HV 307, and 9.17×10⁻⁶ K⁻¹, respectively. The microstructure is fine and uniform, and the fracture morphology is ductile fracture.