变形条件对2091铝锂合金高温变形组织的影响

THE EFFECT OF DEFORMATION VARIABLES ON THE STRUCTURES OF 2091 ALUMINIUM-LITHIUM ALLOY AT ELEVATED TEMPERATURES

利用圆柱样品轴对称等温压缩实验研究了２０９１Ａｌ－Ｌｉ合金高温塑性变形组织特征，分析了合金在变形过程中的组织变化规律。试验应变速率和温度范围分别为１０－３～１０．０ｓ－１和３００～５００℃。结果表明，２０９１合金在高温塑性变形时主要形成亚晶组织。随变形温度升高和应变速率降低，亚晶尺寸增大，亚晶界处的位错排列更为简单和完整。变形时的软化机制主要为动态回复，动态再结晶只在较高的温度和较低的应变速率情况下才出现。仅发生动态回复时形成的平均亚晶尺寸和变形条件之间满足ＨａｌｌＰｅｔｃｈ关系。

The features of the high temperature deformation structures of 2091 Al-Li alloy have been investigated in the present work with the aid of isothermal axisymmetric compression testing of cylinder specimens. the evolution of the deformation structures has been analyzed. The tested temperature and strain rate of interest were in the ranges of 10-3 10.0s-1 and 300 ～ 500 ℃,respectively. The results showed that the subgrain structures had been predominately developed during the plastic deformation of 2091 AI-Li alloy at elevated temperatures. The subgrain size increased with the increase of temperature and decrease of strain rate, While the dislocations arranged into more simple and perfect configurations near subgrain boundaries. The main restoration mecharism was confirmed to be dynamic recovery. Dynamic recrystallization could be solely activated at relatively higher temperatures and lower strain rates.The relationship between the average subgrain size and the deformation variables,including temperature and strain rate, was represented in the form of HallPetch relationship when the alloy was only softened by dynamic recovery.