Oxide/metal interface enhancement for improved dispersion strengthening mechanism in oxide-strengthened tungsten

Abstract

The addition of secondary ceramic particles has shown to be effective in enhancing the mechanical properties of tungsten alloys. The diverse strengthening effects observed with various secondary particles necessitate further investigation. Herein, three ultrafine-grained, oxide-dispersed-strengthened tungsten alloys were prepared using solution combustion synthesis combined with low-temperature sintering. We thoroughly investigated the influence of Al2O3, La2O3, and Y2O3 on the microstructure and mechanical properties of tungsten, as well as their respective strengthening mechanisms. A detailed comparison revealed discrepancies between the yield strength experimentally measured and the theoretically predicted strength based on conventional grain refinement strengthening and dispersion strengthening theories, highlighting the significance of the intrinsic nature of dispersed oxides. Electron microscopy analysis and density functional theory calculations revealed that, compared to other oxides, the heterogeneous interface of Al2O3 with W exhibited minimal lattice distortion and the highest work of separation, resulting in a robust interface bonding. The prepared W-Al2O3 alloy showed exceptional performance with Vickers hardness HV0.2 of 698.9 and yield strength of 2488 MPa. Its yield strength surpassed that of W-Y2O3 and W-La2O3 alloys, as well as other commonly reported refractory metal materials.