Microstructure and mechanical properties of Al2O3/TiAl composite
(1.陕西省咸阳市陕西科技大学材料科学与工程学院
2.School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xianyang 712081, China)
2.School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xianyang 712081, China)
Abstract: Al2O3/TiAl composites were fabricated by PAXD (pressure-assisted exothermic dispersion) method. The effects of Nb2O5 content on the microstructure and mechanical properties of the composites were investigated. The results show that the ultimate phases of the composite consist of TiAl, Ti3Al, Al2O3 and a small amount of NbAl3. SEM reveals that a submicron γ+(α2/γ) dual phases structure can be presented after sintered at 1 200 ℃. Furthermore, with the increase of Nb2O5 content, the ratio of TiAl to Ti3Al phase decreases correspondingly, the grains of the composites are remarkably refined, and the produced Al2O3 particles are uniformly dispersed. When 6% Nb2O5 is added, the composite has the best comprehensive properties. It exhibits a Vickers hardness of 4.77 GPa and a bending strength of 642 MPa. Grain-refinement and dispersion-strengthening are the main strengthening mechanisms.
Key words: exothermic dispersion; Al2O3/TiAl composite; microstructure; mechanical properties