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用透射电子显微术和X射线能谱术研究了Ti_3Al-11Nb(Ti-12.5wt%Al-21wt%Nb)合金热锻棒材在热处理过程中的相变特征。结果表明,合金在1100℃加热后缓冷到室温的样品其组织由α_2+β相组成。与α_2相相比,β相明显地表现出Al含量低而Nb含量高。1200℃油淬样品的组织由α_2+B2相组成,二相含量大致相近。1200℃水淬样品由单一的B2相组成。水淬并经750℃时效的样品中析出两种形态的α_2相:首先由晶界析出的较粗的α_2相以及在晶内普遍析出的弥散的α_2相。
The phase transition characteristics of hot forged Ti_3Al-11Nb (Ti-12.5wt% Al-21wt% Nb) alloy during heat treatment were investigated by transmission electron microscopy and X-ray energy dispersive spectroscopy. The results show that the microstructure of the samples annealed to room temperature after being heated at 1100 ℃ consists of α_2 + β phase. Compared with α_2 phase, β phase obviously shows low Al content and high Nb content. The microstructure of samples hardened at 1200 ℃ is composed of α_2 + B2 phases, and the content of two phases is similar. 1200 ℃ water quenching sample consists of a single B2 phase composition. Two kinds of α_2 phases were precipitated in water quenched and aged at 750 ℃. The coarse α_2 phase firstly precipitated from the grain boundary and the dispersed α_2 phase precipitated in the crystal.