In this paper, the evolution of primary α (α_p) and its effect on microtexture during post-deformation heat treatment of Ti6242S alloy were investigated. It was found that in the obtained bimodal microstructures, there existed three types of α/α misorientation angles in elongated α_p grains, and their formation was closely related to the BOR (Burgers orientation relationship) between α_p and the neighboring β grains. During the heat treatment, the boundary splitting tended to refine α_p grains, which was not only associated with α/α misorientation angle, but also the BOR between α_p and β phases. If the effect of pre-deformation on the diffusion rate of solute elements was considered, the boundary splitting time quantitatively predicted by the Mullins model was greatly underestimated. Meanwhile, the crystallographic orientation distributions of bimodal microstructures were inhomogeneous, and the microtextured areas were formed. This was because when α_p and the neighboring β grains obeyed a BOR, secondary α (α_s) colony preferentially precipitated at α_p/β interface and occupied a larger area, and α_s colony kept a similar orientation with the α_p. Moreover, α_s colonies enhanced the pre-existing α_p texture components, which led to local area displaying a cluster of α phase with similar orientations.

本文研究了 Ti6242S 合金变形后热处理过程中初生α ( α _p )的演变及其对显微组织的影响。发现在获得的双峰显微组织中，拉长的α _p晶粒中存在三种类型的α/α错取向角，它们的形成与α _p与相邻β晶粒之间的BOR（Burgers取向关系）密切相关。在热处理过程中，边界分裂趋向于细化α _p晶粒，这不仅与α/α取向角有关，而且与α _p和β相。如果考虑预变形对溶质元素扩散速率的影响，则大大低估了Mullins模型定量预测的边界分裂时间。同时，双峰微结构的晶体取向分布不均匀，形成了微织构区。这是因为当α _p和相邻的β晶粒服从 BOR 时，次生 α ( α _s ) 菌落优先沉淀在α _p /β界面并占据更大的面积，并且α _s菌落保持与α _p相似的取向. 此外，α _s菌落增强了预先存在的α _p纹理成分，导致局部区域显示出具有相似方向的α相簇。