Effects of elemental Nb addition on the microstructures and mechanical properties of Ti/Al2O3 composites by pressureless sintering

摘要

Nb and Nbsub2/subOsub5/sub were used, respectively, as sintering additives for pressureless sintering of Ti/Alsub2/subOsub3/sub composites, and the effect of elemental Nb on the microstructures and mechanical properties of the composites were investigated. The X-ray diffraction results indicated that the addition of both Nb and Nbsub2/subOsub5/sub resulted in the solution of Nb in Ti. Compared to metal Nb, the addition of Nbsub2/subOsub5/sub made the composites easier to sinter, and the density of the Ti/Alsub2/subOsub3/sub composite rose with increases in the Nbsub2/subOsub5/sub addition. When metal Nb was added, the changes in flexural strength and micro-hardness were basically consistent with the variations in density. The strength of the Ti/Alsub2/subOsub3/sub composites was found to increase at first and then to decrease, however when Nbsub2/subOsub5/sub was added. The phase formation and strengthening mechanisms are illustrated. The best performance occurred when 5 vol.% Nbsub2/subOsub5/sub was added, with a relative density, micro-hardness and flexural strength of 89.3%, 5.6 GPa and 115.78 MPa, respectively.