Ti2AlNb板材的热拉伸行为和微观组织演化机理

Hot tensile behavior and microstructure evolution mechanism of Ti2AlNb sheet

摘要:

本文通过高温拉伸试验研究了Ti-22Al-24.5Nb-0.5Mo合金在温度范围为910~1040℃、应变速率为0.0001~0.1-1条件下的高温变形行为。建立了B2/β+O、α2+B2/β+O和α2+B2/β三个不同相区的Arrhenius方程，并通过多种微观组织观察技术研究了微观组织演化机理。结果表明：在B2/β+O、α2+B2/β+O和α2+B2/β三个相区的激活能分别为759.43kJ/mol，516.71kJ/mol和438.59kJ/mol。微观组织演化主要是O相晶粒的动态再结晶和B2/β相晶粒的动态回复，在B2/β+O相区的软化机制是片层O相晶粒的球化，而在α2+B2/β+O相区的软化机制是B2/β相晶粒的动态再结晶及局部剪切带的形成。

Abstract:

The hot tensile behavior of Ti-22Al-24.5Nb-0.5Mo (at.%) alloy was investigated by the hot tensile tests at the temperature 910-1040°C and the strain rate 0.0001s-1-0.1s-1. The Arrhenius equations were calculated at the three different phase fields and the microstructure evolution mechanisms were studied by microstructure observation. The results show that the activated energies were 759.43kJ/mol, 516.71kJ/mol and 438.59kJ/mol at B2/β+O, α2+B2/β+O and α2+B2/β phase fields, respectively. The microstructure evolution were dominated by dynamic recrystallization of O-phase and dynamic recovery of B2/β phase grains, and the softening mechanism was the globularization of O lamellar grains at B2/β+O phase field, while the softening mechanism was dynamic recrystallization and shear bands of the B2/β-phase grains α2+ B2/β+O.