利用塔菲尔(Tafel)极化曲线测试方法和电化学阻抗(EIS)测试方法,研究了镍基合金925在饱和H2S盐水环境下腐蚀过程不同时段的电化学行为。结果表明:在饱和H2S盐水作用下,试验开始至第9 d时腐蚀电位一直在降低,最低-418 m V,随后腐蚀电位...利用塔菲尔(Tafel)极化曲线测试方法和电化学阻抗(EIS)测试方法,研究了镍基合金925在饱和H2S盐水环境下腐蚀过程不同时段的电化学行为。结果表明:在饱和H2S盐水作用下,试验开始至第9 d时腐蚀电位一直在降低,最低-418 m V,随后腐蚀电位逐渐升高,第17 d时腐蚀电位达-301 m V,而腐蚀电流在第5 d之前降低至1.2μA,第9 d升高至2.57μA,之后一直降低1.55μA。电化学阻抗谱显示高频区的容抗弧越来越小,扩散特征增强,可能是形成的腐蚀钝化膜不够致密。综合分析认为试验进行5 d后原有的氧化膜破坏,开始形成新的保护膜,9 d后合金钝化效果明显,合金耐腐蚀性增强。展开更多
In the present work, the orientation characteristics of residual grains during hot deformation of an age-hardening Ni-Fe-Cr alloy(Alloy 925) at different conditions were systematically analyzed through high-resolution...In the present work, the orientation characteristics of residual grains during hot deformation of an age-hardening Ni-Fe-Cr alloy(Alloy 925) at different conditions were systematically analyzed through high-resolution electron back-scatter diffraction. Based on the measurement of the kernel average misorientation, the density of geometrical necessary dislocations(GNDs) was further calculated. The orientation-dependent deformation mechanism of the residual grains was also discussed using Schmid factor difference ratio(SFDR) analysis. The results show that the deformed microstructure features typical "necklace" structures. Many distorted twin boundaries can be observed within the residual grains at 950 ℃. When the deformation temperature increases to 1150 ℃, the volume fraction of dynamic recrystallization(DRX) increases, leading to the extensive formation of primary Σ3 twin boundaries. Additionally, the GNDs are widely distributed in the residual grains, while they are rare for the recrystallized grains. The maximum GND density value can be obtained at the interface of "soft–hard" grains. The GND density also increases at higher strain rates, and the number of DRX grains significantly affects the distribution of the GND density. Moreover, based on the calculations and SFDR analysis, it can be summarized that the {100} and {111} grains are prone to deform in the uniserial slip mode and the multiple slip mode, respectively.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51701028 and 51421001)the Opening Project of Jiangsu Province Key Laboratory of High-end Structural Materials(No.HSM1901)+1 种基金the Open Research Fund from the State Key Laboratory of Rolling and Automation(No.2020RALKFKT016)the Venture&Innovation Support Program for Chongqing Overseas Returnees(No.CX2018056)。
文摘In the present work, the orientation characteristics of residual grains during hot deformation of an age-hardening Ni-Fe-Cr alloy(Alloy 925) at different conditions were systematically analyzed through high-resolution electron back-scatter diffraction. Based on the measurement of the kernel average misorientation, the density of geometrical necessary dislocations(GNDs) was further calculated. The orientation-dependent deformation mechanism of the residual grains was also discussed using Schmid factor difference ratio(SFDR) analysis. The results show that the deformed microstructure features typical "necklace" structures. Many distorted twin boundaries can be observed within the residual grains at 950 ℃. When the deformation temperature increases to 1150 ℃, the volume fraction of dynamic recrystallization(DRX) increases, leading to the extensive formation of primary Σ3 twin boundaries. Additionally, the GNDs are widely distributed in the residual grains, while they are rare for the recrystallized grains. The maximum GND density value can be obtained at the interface of "soft–hard" grains. The GND density also increases at higher strain rates, and the number of DRX grains significantly affects the distribution of the GND density. Moreover, based on the calculations and SFDR analysis, it can be summarized that the {100} and {111} grains are prone to deform in the uniserial slip mode and the multiple slip mode, respectively.
