【摘要】 采用等温热压缩测试和TEM分析研究铝锂合金的流变行为与组织演化规律。结果表明:合金的热塑性变形过程受热激活控制,当变形温度低于410℃时,流变曲线具有明显的峰值应力,曲线由加工硬化、动态软化和稳定阶段3个阶段组成;当变形温度高于410℃后,峰值应力不明显。随应变量的增加,合金组织演化规律为产生大量无规则缠结位错→"多边化"形成"位错墙"→分割原始晶粒成若干亚晶→亚晶合并长大并同时经受变形→重复上述过程。应变量的增加导致大量空位产生,刃型位错更易攀移、重组和对消,晶内形成亚晶组织。求解得到合金的材料常数如下:结构因子A为2.787×1016;变形激活能Q为217.397 k J/mol;应力指数n为6.11656;应力水平参数α为0.012568 mm2/N。应变速率和温度对合金流变应力的影响可以用包含Arrhenius等式的Z参数表示。更多还原

【Abstract】 The flow behavior and microstructure evolution of Al-Li alloy were investigated by isothermal compression tests and TEM analysis. The results show that the hot plastic deformation of the alloy is heat activation process. The flow curve consists of work hardening, dynamic softening and stabilization stage, and it has obvious peak stress when the deformation temperature is below 410 ℃. Otherwise, when the deformation temperature is above 410 ℃, the peak stress is not obvious. The microstructure evolution of the test alloy experiences irregular dislocation tangles→polygonization forming dislocation walls→segmentation of the original grain into several subgrains→the coalescence and growth of subgrains undergoing deformation→repeating the above process with increasing the strains. And increasing the strain causing the increase in the number of vacancies, leading to edge dislocation easier to climb, rearrangement and annihilation and formation of subgrains in intragranular. The constants of alloy material are obtained as follows:structure factor A of 2.787×1016, deformation activation energy Q of 217.397 k J/mol, stress exponent n of 6.11656,stress level parameter α of 0.012568 mm2/N. The effects of strain rate and temperature on the hot deformation behavior were represented by Zener-Hollomon parameter including Arrhenius term.更多还原