Pure molybdenum (PM) and La₂O₃ dispersion strengthened Mo alloy (ODS-Mo) were prepared by powder metallurgy through two different mixing method (solid-solid or SS mixing and solid-liquid or SL mixing). After annealed at 1050 °C for 1 h, the PM, SS-Mo and SL-Mo were compared in microstructure and mechanical properties. The microstructural examinations showed that the PM was mostly recrystallized with rather coarse grains, but the ODS-Mo alloys remained fine elongated grains. This discrepancy is due to a higher recrystallization temperature held in the ODS-Mo alloys. The uniaxial testing results showed that the ODS-Mo had higher tensile mechanical properties compared to the PM, which are attributed to the remarkable strengthening and ductilizing effect induced by the La₂O₃ particles. The low cycle fatigue (LCF) testing results revealed that the PM experienced cyclic hardening behaviors, while the ODS-Mo alloys exhibited cyclic softening behaviors. The Basquin-Manson-Coffin analyses results demonstrated that the ODS-Mo possessed a higher fatigue ductility and longer fatigue life than the PM. Two kinds of cracks, i.e., cleavage cracks and intergranular cracks, were experimentally observed to coexist on the fracture surface. In particular in the SL-Mo alloy, the two crack interacted and propagated forward until final fracture, leading to a step-like crack growth path and concomitantly enhanced fatigue ductility. In addition, different cycling dislocation structures were revealed between the PM and ODS-Mo alloys. Cycle fatigue mechanisms responsible for the fatigue behaviors and microstructure evolution during LCF testing were discussed. The best LCF resistance combined with superior uniaxial tensile mechanical properties found in the SL-Mo alloy were rationalized.

采用两种不同的混合方法（固-固或SS混合以及固-液或SL混合），通过粉末冶金法制备了纯钼（PM）和La ₂ O ₃弥散强化钼合金（ODS-Mo）。在1050°C退火1 h后，比较了PM，SS-Mo和SL-Mo的微观结构和力学性能。显微组织检查表明，PM大多以较粗的晶粒重结晶，但ODS-Mo合金仍为细的细长晶粒。这种差异是由于ODS-Mo合金中保持较高的再结晶温度引起的。单轴测试结果表明，ODS-Mo比PM具有更高的拉伸机械性能，这归因于La ₂诱导的显着增强和延展作用。Ø ₃粒子。低循环疲劳（LCF）测试结果表明，PM经历了循环硬化行为，而ODS-Mo合金则表现出循环软化行为。Basquin-Manson-Coffin分析结果表明，ODS-Mo比PM具有更高的疲劳延展性和更长的疲劳寿命。实验上观察到断裂表面共存在两种裂缝，即劈裂裂缝和晶间裂缝。特别是在SL-Mo合金中，两个裂纹相互作用并向前传播，直到最终断裂，从而导致了阶梯状的裂纹扩展路径并随之增强了疲劳延展性。此外，在PM和ODS-Mo合金之间发现了不同的循环位错结构。讨论了在LCF测试过程中负责疲劳行为和微观结构演变的循环疲劳机理。合理化了在SL-Mo合金中发现的最佳的LCF抵抗力和优越的单轴拉伸机械性能。