利用原位中子衍射室温压缩实验、EBSD和TEM等手段研究了变形速率对GH3625合金弹-塑性变形行为的影响。结果表明,GH3625合金宏观应力-应变曲线包括弹性变形阶段(施加应力σ ≤ 300 MPa)、弹-塑性转变阶段(300 MPa < σ ≤ 350 MPa)和塑性变形阶段(σ > 350 MPa),这与细观晶格应变行为一致。同时,变形速率与晶体弹性和塑性各向异性密切相关。通过特定hkl反射的晶格应变、峰宽和强度的研究结果表明,变形速率对晶体弹性各向异性影响较小,而对晶体塑性各向异性影响较大。随变形速率的增加,大角度晶界逐渐向小角度晶界转变,孪晶界的比例逐渐减小,晶粒由均匀变形向不均匀变形转变。随变形速率的增加,合金的总位错密度(ρ)先减小后增加,而几何必须位错密度(ρ^GND)单调递增,统计存储位错密度(ρ^SSD)单调递减；同时,试样在变形速率为0.2 mm/min时表现出反常的加工硬化行为,这主要与均匀变形产生的统计储存位错(SSD)有关；此外,位错强化贡献和TEM观察证实了GH3625合金的塑性变形机制以位错滑移为主,其加工硬化机制是位错强化。

GH3625 alloy is a typical polycrystalline material. The mechanical properties of a crystal within the alloy depend on the single crystal properties, lattice orientation, and orientations of neighboring crystals. However, accurate determination of single crystal properties is critical in developing a quantitative understanding of the micromechanical behavior of GH3625. In this study, the effect of deformation rate on the elastoplastic deformation behavior of GH3625 was investigated using in situ neutron diffraction room-temperature compression experiments, EBSD, and TEM. The results showed that the microscopic stress-strain curve included elastic deformation (applied stress σ ≤ 300 MPa), elastoplastic transition (300 MPa < σ ≤ 350 MPa), and plastic deformation (σ > 350 MPa) stages, which agreed with the mesoscopic lattice strain behavior. Meanwhile, the deformation rate was closely related to the crystal elastic and plastic anisotropy. The results of the lattice strain, peak width, and peak intensity reflected by the specific hkl showed that the deformation rate had little effect on the elastic anisotropy of the crystal, but had a significant effect on the plastic anisotropy of the crystal. With the increase in the deformation rate, the high angle grain boundaries gradually changed to the low angle grain boundaries, and the proportion of twin boundaries gradually reduced. Also, the grains transformed from uniform deformation to nonuniform deformation. Moreover, with the increase in deformation rate, the total dislocation density (ρ) of the alloy first decreased and then increased, whereas the geometrically necessary dislocation density (ρ^GND) monotonically increased, and the statistically stored dislocation (SSD) density (ρ^SSD) monotonically decreased. Meanwhile, the abnormal work hardening behavior of the sample at a deformation rate of 0.2 mm/min was mainly related to the SSD generated by uniform deformation. Additionally, the contribution of dislocation strengthening and TEM observation confirmed that the dominant deformation of GH3625 was dislocation slip, and its work hardening mechanism was dislocation strengthening.