【摘要】：對Ti-50Al-6Nb(at%)合金進行不同生長速度下的定向凝固實驗,研究了生長速度對微觀組織演變、相變路徑、微觀偏析和硬度值的影響。結(jié)果表明,在較低的生長速度下(≤10μm/s),凝固過程為完全β相凝固,固液界面隨生長速度的增加發(fā)生平胞枝轉(zhuǎn)變,最終得到α2/γ層片組織(在10μm/s時為α2/γ+B2相的組織),其中層片結(jié)構(gòu)與生長方向呈45°或0°夾角。在較高速度(≥15μm/s)時,初生相為α相,固液界面為規(guī)則枝晶生長。最終組織為α2/γ層片組織,并與生長方向呈90°夾角。該成分合金的硬度值隨著生長速度的增加而增加。與其它合金相比,該成分合金的硬度值較小。
[Abstract]:The effects of growth rate on microstructure evolution, phase transition path, micro segregation and hardness of Ti-50Al-6Nb (at%) alloy were investigated by unidirectional solidification experiments at different growth rates. The results show that at a low growth rate (10 渭 m / s), the solid-liquid interface is completely 尾-phase solidified, and the solid-liquid interface changes with the increase of the growth rate. Finally, 偽 _ 2 / 緯 lamellar structure (偽 _ 2 / 緯 _ 2 phase at 10 渭 m / s) was obtained, in which the lamellar structure and growth direction were 45 擄or 0 擄. At higher speed (鈮，

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