The influence of modification route on the properties of W-0.3 wt% Y2O3 powder and alloy prepared by nano-in-situ composite method

To produce high-performance W-Y2O3 material, a novel powder synthesis process named nano-in-situ composite method is proposed in this article. This process mainly includes nano-in-situ composite heterogeneous precipitation, spray drying, calcination and hydrogen-thermal reduction, subsequent with conventional sintering. In order to improve the performance of the alloy, powder modification is introduced during powder synthesis. The influence of powder modification on the properties of powder and corresponding alloys were investigated systematically. Results show that, Y2O3 uniform inlaid tungsten structure composite powder can be prepared by nano-in-situ composite method, and the mechanism of nano in-situ composite synthesis was analyzed. The modified W-Y2O3 composite powders of after calcination display better dispersity, lower oxygen content, smaller particle size, and its sintering bodies displayed higher density, and higher hardess. The particle size and oxygen content of the synthesized powders can reach 160 nm and 0.21%, respectively. This powders have high sintering activity. They can be sintered to near full density at 1880 degrees C by conventional sintering method. Whereas the W-Y2O3 composite material prepared by non-modified powders display smaller grains, better tensile strength and a more uniform distribution of the second phase. The sintered alloy has W grain sizes of only 1-2 mu m, which is beneficial for its mechanical properties. And its tensile strength and microhardness at room temperature can is 445.4 MPa, 614HV, respectively. Compared with the previously reported preparing method, which is usually mechanical alloying (MA) or wet chemical method followed by SPS or hot pressing, this method can effectively improve the density and mechanical properties of W-Y2O3 composite material. Additionally, this method uses the conventional sintering, so it is suitable for engineering production. (C) 2018 Elsevier B.V. All rights reserved.