钛合金片层组织在两相区变形时流动应力随应变的增加普遍表现为快速硬化和持续软化的特征. 为了研究该流动软化的机理, 采用等温热压缩实验研究了TC11合金片层组织在温度890-995 ℃和应变速率0.01-10 s-1范围内的热变形行为. 理论计算表明α/β片层界面(α片层内孪晶界)产生的 Hall-Petch强化效应远大于片层束集边界. TC11合金片层组织高温变形的流动软化机理可归结为硬滑移模式向软滑移模式转变导致Hall-Petch强化效应的减弱.
The flow stress has a considerable flow softening after a peak strain hardening at very low strains for Ti alloys with lamellar structure during subtransus deformation. In order to study the mechanism of such flow softening behavior, the deformation behavior of TC11 Ti alloy with a lamellar structure was studied using isothermal hot compression tests under a temperature range of 890-995 ℃ and a strain rate range of 0.01-10 s-1. Theoretical calculation shows the Hall-Petch strengthening effects induced by α/β interface as well as the twin boundary in $\alpha$ lamellar are far more significant than that of the colony boundary. The flow softening can be related to reduction of Hall-Petch strengthening effects due to transfer from the hard slip mode to the soft one.
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