退火温度对高纯钽棒再结晶织构及力学行为的影响

Effect of Annealing Temperature on Recrystallization Texture and Mechanical Behavior of High Purity Tantalum

摘要:

本文对冷变形后的高纯钽棒进行不同温度(850~1050℃)的退火处理,研究了退火后的微结构及织构演变规律、再结晶形核与取向的依赖性以及再结晶组织对其力学行为的影响。结果表明,冷变形组织呈{100}和{111}取向分布的纤维状结构,以()[]组分为主的α-织构。退火处理后,高纯钽棒组织分别处于回复阶段(850℃)、完全再结晶(950℃)以及晶粒长大阶段(1050℃)。随着退火温度的增加,α-织构逐渐弱化,γ-织构逐渐形成,尤其是完全再结晶后,α-织构组分完全消失。屈服强度和应变硬化能力随着退火温度的增加而降低,塑韧性得到明显改善,完全再结晶时均匀伸长率达到17.85%。当温度增加到1050℃时,二次再结晶晶粒容易发生沿晶断裂,力学性能较差。

Abstract:

In this work, the high-purity tantalum after cold deformation is annealed at different temperatures (850~1050℃). The regularity of microstructure and texture evolution, the dependence of recrystallized nucleation and orientation, and the effect of recrystallized structure on its mechanical behavior were studied after annealing. The results show that the cold-deformed microstructure is the fibrous structure with {100} and {111} orientations, which is dominated by the α-fibre of ()[] component. After annealing, the microstructure of high-purity tantalum is in the recovery stage (850°C), complete recrystallization (950°C) and grain growth stage (1050°C). With increase of annealing temperature, the α-fibre gradually weakened and then the γ-fibre gradually formed, especially the α-fibre is disappeared completely after recrystallization. The yield strength and strain hardening ability decreased with the increase of annealing temperature, and the plasticity was significantly improved, especially the uniform elongation reached 17.85% after recrystallization. When the annealing temperature is increased to 1050°C, the intergranular fracture of the secondary recrystallized grains is prone to occur, resulting in poor mechanical properties.