Abstract
This study was conducted to evaluate the microstructure evolution of the blended elemental powder metallurgy Ti2AlNb alloy with a 2.0 wt% LaB6 addition and the effects of LaB6 doping on the microstructure and mechanical properties of the alloy. The results showed that the microstructure evolution could be divided into two stages. During the first stage, the reaction between Ti and Al powders was dominant. During the second stage, the Nb-enriched area disappeared gradually and microstructural homogeneity was enhanced with the diffusion of Nb. It was demonstrated that the LaB6 phase could be transformed into La2O3, (Ti, Nb)B and the (Ti, Nb)3B2 transition phase in the sintering process. LaB6 addition inhibited the precipitation of the brittle α2 phase and refined the microstructure. Compared with the alloy without LaB6, the Ti2AlNb alloy with 2 wt% LaB6 had 31.5% and 38.4% improvements in the fracture strain at 25 °C and 650 °C, respectively, and its yield strength was also increased.
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