Microstructure and low-cycle fatigue behavior of spray-formed Al–Li alloy 2195 extruded plate were investigated in this work. The spray-formed alloy after hot extrusion experiment was treated with solid solution treatment and artificial aging. Microstructure analysis indicated the aged plate was dominated by elongated unrecrystallized grains, and had a rolling-type texture along extrusion direction with the highest intensity at Brass component. The existence of T₁ phase strengthened the alloy crucially, but δ′ phase was basically absent. Then, the fully-reversed strain-controlled low-cycle fatigue tests were conducted at total strain amplitudes ranging from 0.4% to 1.0% for samples along two orthogonal directions. The stress-strain hysteresis loops were acquired, and the cyclic stress response curves were derived. At low strain amplitudes (0.4–0.5%), the initial cyclic hardening was slight and followed by a cyclic stability, while at higher strain amplitudes (0.6–1.0%), the alloy merely presented a continuously increasing cycle hardening behavior. Moreover, the fatigue life model based on the total strain energy was built and found to be suitable to predict life. Finally, the fatigue fractography observation showed that the fatigue source is relatively concentrated and the fracture surface had typical fatigue striations at 0.5% strain amplitude, while multiple cracks originated on the sample surface and the final fracture zone showed a ductile characteristic at 1.0%. The deformed microstructure near fracture surfaces were observed, and it was found that the cyclic hardening and stability were closely associated with the interaction between moving dislocations and obstacles including (sub)grain boundaries and secondary phase particles against them.

在这项工作中，研究了喷射成形的Al-Li合金2195挤压板的组织和低周疲劳行为。热挤压实验后的喷射成形合金经过固溶处理和人工时效处理。显微组织分析表明，时效钢板以未结晶的细长晶粒为主，并且沿挤压方向具有滚动型织构，在黄铜成分处具有最高强度。T ₁的存在相虽然对合金起到了至关重要的作用，但基本上没有δ'相。然后，沿两个正交方向对样品进行完全反向应变控制的低周疲劳测试，总应变幅度在0.4％至1.0％的范围内。获得了应力-应变磁滞回线，并得出了循环应力响应曲线。在较低的应变幅度（0.4–0.5％）下，初始的循环硬化是轻微的，然后具有循环稳定性，而在较高的应变幅度（0.6–1.0％）下，合金仅表现出持续增加的循环硬化行为。此外，建立了基于总应变能的疲劳寿命模型，发现该模型适合预测寿命。最后，疲劳形貌观察结果表明，疲劳源相对集中，断裂面在0.5％应变幅度下具有典型的疲劳条纹，而试样表面产生了多个裂纹，最终断裂带在1.0％处表现出延性。观察到断裂表面附近的变形微观结构，发现循环硬化和稳定性与运动位错和障碍物（包括（子）晶界和反对它们的第二相粒子）之间的相互作用密切相关。