淬火-回火工艺对Ti-46Al-xB合金柱状晶组织的影响

研究了淬火-回火工艺对Ti-46Al-x B合金柱状晶组织的影响。研究发现,淬火-回火工艺对Ti-46Al-x B合金的柱状晶组织具有明显的细化效果。这主要是由于温度梯度的增加和冷却过程中发生固态相变使晶界或相界面上原子错配,从而形成大量的位错,位错对晶界具有"钉扎"作用,从而细化Ti Al基合金柱状晶组织。结果表明,通过合金化元素B和热处理工艺的共同作用可以获得更为细小的Ti Al基合金柱状晶组织。这主要是由于随着B含量的增加,硼化物的析出量增加,而硼化物对位错线的进一步扩展起到了阻碍作用。从而促进了位错对晶界的"钉扎"作用,进一步细化了Ti Al基合金柱状晶组织。

Effect of Quenching-Tempering Technology on Columnar Structure in Ti-46Al-xB Alloys

The effect of the quenching-tempering process on the columnar structure in Ti-46Al-xB alloys was investigated. It is found that the columnar structures of Ti-46Al-xB alloys are evidently refined by the quenching-tempering process. The reason is that the increase of the temperature gradient and the solid state phase transformation during cooling process lead to atomic mismatch in grain boundary or phase interface, and then a large number of dislocations are formed, which can pin the grain boundary. The experimental results show that finer columnar structure of TiAl-based alloys can be obtained by addition of alloying element B and the heat treatment process. Besides, the addition of B element can impede the extension of dislocations, promoting the effect of anchoring of dislocation, and then the columnar structures are further refined in TiAl-based alloys