Evolution mechanism of lamellar α and interlayered β during hot compression of TC21 titanium alloy with a widmanstätten structure
Evolution mechanism of lamellar α and interlayered β during hot compression of TC21 titanium alloy with a widmanstätten structure
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DOI：
10.1016/j.cja.2021.07.008
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发表时间：
2021-09
影响因子：
5.7
通讯作者：
Xiao-ying Zheng;Ke Wang;Chenghang Zhang;R. Xin;Qing Liu
中科院分区：
文献类型：
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作者：
Xiao-ying Zheng;Ke Wang;Chenghang Zhang;R. Xin;Qing Liu
TC21钛合金作为制造飞机结构件的重要金属，近年来备受关注。对具有魏氏组织的 TC21 钛合金进行等温压缩。基于显微组织观察，系统研究了初始β晶粒、晶界α相（αGB）、层状α相和层间β相的演化。结果表明，随着高度减少的增加，αGB经历了从弯曲/扭结到断裂的演化过程，导致初始粗β晶粒轮廓相应模糊。同时，在破碎的αGB的末端发生了从α到β的显着相变。群体中层状α和层间β的演化与其变形相容性密切相关。在α群体中，层间β比层状α经历了更大的变形量。较高的畸变能促进了动态回复（DRV）和动态再结晶（DRX）的发生，在层间β中产生许多低角边界（LAB）和高角边界（HAB），从而导致β相晶粒明显细化。相反，较低的畸变能和较低的变形温度抑制了DRV/DRX的发生，并抑制了层状α的球化。此外，微观结构观察清楚地表明，剪切分离机制主导了α相从片状形态到短棒状形态的演变。
TC21 titanium alloy, as an important metal to fabricate the aircraft structural components, has attracted great attentions recently. A TC21 titanium alloy with widmanstätten structure was isothermally compressed. Based on the microstructure observation, the evolution of initial β grain, Grain Boundary α phase (αGB), lamellar α and interlayered β was systematically investigated. The results showed that, with the increasing of height reduction, the αGBunderwent an evolution process from bending/kinking to breaking inducing the corresponding blurring of initial coarse β grain outline. Meanwhile, a significant phase transformation from α to β took place at the terminations of broken αGB. The evolution of lamellar α and interlayered β in the colony was closely related to their deformation compatibility. In the α colony, the interlayered β experienced a larger deformation amount than lamellar α. The higher distortion energy promoted the occurrence of Dynamic Recovery (DRV) and Dynamic Recrystallization (DRX) to generate many Low Angle Boundaries (LABs) and High Angle Boundaries (HABs) in interlayered β, which induced an apparent grain refinement of β phase. On the contrary, the lower distortion energy and low deformation temperature suppressed the occurrence of DRV/DRX and restrained the globularization of lamellar α. Furthermore, the microstructure observation clearly revealed that the shearing separation mechanism dominated the evolution of the α phase from lamellar to short bar-like morphology.