Although the amount of Cr in chemical composition of 7xxx series alloys is usually less than 0.1 wt%, it significantly affects the properties and microstructural evolutions during thermo-mechanical processing of these alloys. In this study, the effect of the elimination of Cr on the microstructural evolutions of ECO-7175 alloy during hot deformation is investigated. ECO-7175 alloys with and without Cr were subjected to hot compression at 350, 400, 450, and 500 °C and strain rates of 0.001, 0.01, 0.1, and 1 s⁻¹. The microstructural evolutions of the alloys were studied through Optical Microscopy, Scanning Electron Microscopy, Scanning Transmission Electron Microscopy, and Electron Backscatter Diffraction analysis. Scanning Electron Microscope and Scanning Transmission Electron Microscope observations revealed that removal of Cr eliminates ε precipitates from microstructure of the alloy. The elimination of ε precipitates that act as Zener pining agents were found to affect the kinetics of static recrystallization of the initial materials during the preheating and mechanisms of dynamic restoration of the alloy during hot deformation. Although the microstructural observations revealed that continuous dynamic recrystallization and dynamic recovery were the main restoration mechanisms for both alloys, Electron Backscatter Diffraction analysis showed that the finely dispersed ε precipitates impede movement and rearrangement of dislocations and slow down the rate of dynamic recovery and continuous dynamic recrystallization in the Cr-containing samples.

尽管7xxx系列合金化学成分中的Cr含量通常小于0.1 wt％，但在这些合金的热机械加工过程中，Cr的含量会显着影响其性能和微观组织演变。在这项研究中，研究了Cr的去除对ECO-7175合金热变形过程中组织演变的影响。将具有和不具有Cr的ECO-7175合金分别在350、400、450和500°C下进行热压缩，应变率分别为0.001、0.01、0.1和1 s ^-1。通过光学显微镜，扫描电子显微镜，扫描透射电子显微镜和电子背散射衍射分析研究了合金的微观结构演变。扫描电子显微镜和扫描透射电子显微镜的观察表明，Cr的去除消除了合金微观结构中的ε沉淀。发现消除了用作齐纳峰固定剂的ε沉淀物会影响预材料在预热过程中的静态重结晶动力学，以及在热变形过程中动态恢复合金的机理。尽管显微组织观察表明，连续动态再结晶和动态恢复是两种合金的主要恢复机制，