Article
Chemistry, Physical
Sihan Cheng, Jiaqi Wang, Yunsheng Wu, Xuezhi Qin, Lanzhang Zhou
Summary: The effects of Fe content on the microstructure, thermal stability, and tensile properties of a Ni-Fe-Cr based superalloy used in advanced ultra-supercritical power plants were investigated. It was found that Fe content influenced the precipitation behavior and morphology of different phases in the alloy. Fe content improved the ductility but slightly reduced the strength of the alloy. Long-term thermal exposure resulted in a phase transformation of gamma ' phase from spherical to cubic shape in the alloy with 35% Fe content. The coarsening rate of gamma ' phase decreased with increasing Fe content due to the restricted diffusion of Fe atoms. The change in yield strength with particle size was explained by dislocation shearing and Orowan bowing models. Precipitation of harmful Laves phase at intermediate stage of thermal exposure led to a more rapid reduction in yield strength when Fe content was 35%.
Article
Nanoscience & Nanotechnology
Yayun Li, Pingwei Xu, Wei Jiang, Lei Zhou, Zihao Jiang, Yilong Liang, Yu Liang
Summary: The effect of ultrasonic surface rolling process (USRP) and post-treatment on the microstructure and elevated-temperature tensile properties of ATI 718Plus were investigated. The study found that the USRP-treated samples exhibited a gradient distribution of eta-Ni-3(Al0.5Nb0.5) phase and recrystallized grains on the surface, which stabilized the trans-scale grain hierarchy. This heterogeneous microstructure promoted the accumulation of high-density geometrically necessary dislocations near the grain boundaries and resulted in additional hardening during plastic deformation, resulting in improved tensile properties at high temperatures.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Chemistry, Physical
Xiaosheng Zhou, Haokai Dong, Yushuai Wang, Meini Yuan
Summary: In this study, a Fe-Cr-Ni-Al-Ti ferritic superalloy was fabricated by hot isostatic pressing (HIP) and the types and evolution of precipitates were investigated. The results showed that the precipitates could be completely dissolved during solution treatment at 1100 degrees C, while they underwent morphological evolution and coalescence after aging at 700 degrees C. The alloy exhibited high tensile strength and elongation, but failure may occur at the initiation of cracks.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Nanoscience & Nanotechnology
Shengyu Zhou, Minghao Hu, Chong Li, Qianying Guo, Liming Yu, Haimin Ding, Yongchang Liu
Summary: The correlation between microstructure-properties in a Ni-based superalloy and the coprecipitation of gamma'/gamma'' phases has been extensively studied. Experimental results show that a high amount of compact gamma'/gamma'' phases contributes to the tensile strength of the alloy, which decreases with the coarsening of the gamma'/gamma'' structures. The gamma'/gamma'' phases can hinder the motion of dislocations, and their size influences the deformation mechanisms.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Nanoscience & Nanotechnology
Peng Liu, Rui Zhang, Yong Yuan, Chuanyong Cui, Faguang Liang, Xi Liu, Yuefeng Gu, Yizhou Zhou, Xiaofeng Sun
Summary: The study investigated the influence of nitrogen content on a newly developed Ni-Fe based superalloy for ultra-supercritical power plant applications beyond 700℃. The results showed that an increase in nitrogen content promoted changes in carbide morphology and grain boundary phase formation, with little effect on yield and tensile strength but significantly improving ductility. The alloy exhibited a mixture fracture mode and a dominant deformation mechanism of gamma ' bypassing via Orowan looping.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Gang Liu, Lingbing Kong, Xueshan Xiao, Soran Birosca
Summary: Lowering the Ti/Al ratio results in slightly smaller average gamma' size and higher volume fraction of gamma'. Moreover, gamma' in samples with low ratios retains spherical morphologies after long-term ageing compared to high ratio samples, which transform to cuboidal shape in later ageing stage due to higher lattice misfit. Clear M23C6 carbides coarsening at grain boundary and growth toward grain interior in lower ratio samples during ageing process.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Bao Wan, Xiao-Qiang Li, Cun-Liang Pan, Dong-Yu Li, Sheng-Guan Qu, Chao Yang
Summary: A novel Ti-Zr-Fe-Cu-Ni-Co-Mo filler metal was used to join TiAl to GH536, and the effects of brazing temperature on interfacial microstructure and chemical composition were analyzed. The shear strength and brazing seam thickness initially increased and then decreased with increasing brazing temperature, with joint performance being controlled by brazing seam thickness and formation of intermetallic compounds.
Article
Materials Science, Multidisciplinary
Hongyu Chen, Junming Gou, Wentao Jia, Xin Song, Tianyu Ma
Summary: This study investigates the origin of appealing hard magnetic properties in non-equiatomic magnetic high-entropy alloys through detailed microstructural and chemical analysis. The results show that the as-cast alloy has a hierarchically heterogeneous microstructure with nano-arrays enriched or depleted with ferromagnetic element. The aspect ratio and elemental concentration of the nano-arrays can be manipulated by magnetic annealing, significantly enhancing the coercivity.
Article
Nanoscience & Nanotechnology
Yeshun Huang, Rui Zhang, Zijian Zhou, Peng Zhang, Jingbo Yan, Yong Yuan, Yuefeng Gu, Chuanyong Cui, Yizhou Zhou, Xiaofeng Sun
Summary: The tensile properties and deformation mechanisms of a Fe-Ni-based superalloy were investigated at 700 degrees C with different sizes of gamma ' precipitates obtained through varied aging time. The yield strength of the alloy increased first and then decreased with the increase of aging time, which was consistent with the change of critical resolved stress of deformation mechanism. The dominant deformation mode changed from weakly-coupled dislocation pairs with slip bands to Orowan looping as the size of gamma ' precipitates increased, resulting in the occurrence of peak value of strength. When the gamma ' size was above 40 nm, the dominant deformation mechanism was Orowan bowing along with stacking fault shearing, decreasing the yield strength of the alloy. When the gamma ' size was between 30 nm and 40 nm, the dominant deformation mechanism was Orowan looping with strongly-coupled dislocation pairs and the fracture mode was intergranular. Intermediate temperature brittleness occurred in the secondary aging treated alloy with a gamma ' phase size of approximately 30 nm, which was attributed to the increase in critical resolved stress and strain localization caused by the transformation of tensile deformation mechanism, and stress concentration due to dislocation entanglement at grain boundary. The sub-aging state of the alloy used for advanced ultra-supercritical plants may be a good choice for obtaining simultaneously favorable strength and ductility.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Z. Q. Zhou, P. Zhang, J. B. Yan, G. Y. Zhou, J. J. Shi, G. H. Cao, Y. Yuan
Summary: The microstructure evolution and deformation behavior of the Ni-Fe-based superalloy HT650T under creep conditions were investigated using scanning electron microscopy with electron backscattered diffraction and transmission electron microscopy. It was found that the precipitates in the alloy consisted of gamma' phases, MC and M23C6 carbides, and no gamma'-free regions were observed. With temperature and duration of creep increasing, the gamma' precipitates grew gradually but maintained their spherical shape, while the M23C6 carbides coarsened and exhibited continuous morphology in some regions. The interaction between dislocations and gamma' precipitates was controlled by the Orowan looping mechanism. Stress concentration primarily occurred at high-angle grain boundaries, and crack propagation was hindered by specific grain boundaries. The excellent creep rupture resistance of HT650T alloy was attributed to the morphology and microstructural stability of phase constituents.
MATERIALS CHARACTERIZATION
(2023)
Article
Materials Science, Multidisciplinary
Yinfei Ju, Huiyu Wang, Peng Sang, Zan Zhang, Kaiyue Li, Hongli Long, Yongsheng Li
Summary: In this study, the evolution kinetics of y'-Ni3Al phase in Ni-15Al-2Mo alloy under creep stress was investigated using phase-field modeling method, which revealed the directional diffusion of elements between y/y' phases. It was found that the increase of Al concentration and the decrease of Mo concentration both promoted the directional connection of y' phase. The difference of chemical potential and elastic potential between y phase and y' phase drove the elements directional diffusion between y/y' phases, with Mo playing a leading role.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Jianwei Teng, Xiaojuan Gong, Biaobiao Yang, Shu Yu, Ruilin Lai, Jiantao Liu, Yunping Li
Summary: The novel high-temperature alloy demonstrates excellent oxidation resistance during the oxidation process, mainly attributed to the continuous formation of Ti-rich oxide on the external surface, inhibiting the volatilization of Cr2O3, and the fine Al2O3 particles along the grain boundaries of the alloy matrix effectively blocking the inward diffusion of oxygen and outward diffusion of chromium.
Article
Nanoscience & Nanotechnology
Riddhi Sarkar, Bo Chen, Michael E. Fitzpatrick, Tim Hilditch, Daniel Fabijanic
Summary: This study reports on the adoption of TiB2 as an inoculant in the fabrication of IN718 through the direct energy deposition (DED) process. Effective grain refinement and low texture were achieved in the IN718/TiB2 samples with specific TiB2 powder size and mass fraction. Deposits made with low linear energy density were free from large grains, but had interlayer defects. Production of deposits without interlayer defects was possible by reducing the powder flow rate, although this resulted in a moderate increase in grain size. The addition of TiB2 as an inoculant reduced the Laves phase network and increased the tensile strength of IN718, but reduced its ductility.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Engineering, Mechanical
Zhou Li, Y. C. Lin, Lu Zhang, Jinhu Zheng, Jingwei Zhao, Rui Wang, Zhengyi Jiang
Summary: This study investigated the tensile properties, microstructural evolution, and deformation behaviors of a new explosive welded TA1/5083 composite sheet, revealing the formation of a wavy transition zone, predominant occurrence of slip bands on the 5083 side, and significant increase in dislocation density in the 5083 layer.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Chemistry, Physical
Yingkun Liu, Bin Yin, Peng Deng, Tongyun Hu, Chunming Deng, Min Liu, Chaoqun Wu
Summary: In this study, a 40 µm (Ni, Pt)Al coating was applied to a fourth-generation single nickel-based superalloy via electroplating followed by aluminizing. High temperature endurance test and isothermal oxidation test were conducted to investigate the microstructure evolution and interdiffusion behavior of the coating and substrate. The results showed that the microstructure of the superalloy coarsened under tensile stress and exhibited a rafting structure. The coating thickness decreased and the Al2O3 layer on the surface became incomplete under tensile stress, and stress reduced the amount of TCP phases in the interdiffusion zone between the coating and the substrate.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
