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Turbine blades are the most demanding components in aircraft engines, and their performance is related to the safety of the whole engine. Due to the complex service environment and harsh service conditions of blades, various types of damage cannot be prevented in service. Therefore, it is of great engineering and economic significance to study the service damage of blades. In this paper, the directional solidification alloy turbine blade after actual service was selected as the research object. The cross section position of 80% upper height of the blade was intercepted, and the qualitative and quantitative microstructure analysis was carried out by SEM and EDS analysis. The results show that there are two different types of γ' phases in this leaf. One kind of γ' phase has small size and regular shape, the other has large size and irregular shape. The degree of microscopic damage among different parts of the blade is characterized with the help of dimensional distribution characterization of the γ' phase of each part, combined with the analysis of hardness testing of each part of the cross-section.The results show that the service conditions of different parts are different, and the degree of microstructure damage is different. In addition, matrix crack and coating crack in some parts of blade are summarized and analyzed.

This study explored the structural stability, elastic properties, structural transformation, and critical concentration of Ni3Al and Ni3M (M = Ti, Ta, Nb) using L12, D024, and DO22 structures, along with three-dimensional supercells featuring stacking faults along [ 10 1 ¯ ] , [ 01 1 ¯ ] , [111] directions. First-principles calculations revealed that the most stable structures for Ni3Al, Ni3Ti, Ni3Ta, and Ni3Nb are L12, D024, DO22, and DO22, respectively. Notably, the bulk modulus, Young′s modulus, shear modulus, and isotropy of Ni3Ti, Ni3Ta, and Ni3Nb surpassed those of Ni3Al, with increased ductility, except for Ni3Ti. By substituting Al atoms with 0–8 Ti, Ta, and Nb atoms in a 32-atom Ni3Al structure, the critical concentration for the transformation from L12 to D024 or DO22 ranged between 18.75 at. % and 21.88 at. %, and between 15.63 at. % and 18.75 at. %, respectively. This critical concentration was influenced by the dynamic interplay among Ti, Ta, Nb, and Al atoms interacting with Ni atoms. The structural transformation from L12 to D024 or DO22 can be attributed to the reduction in the superlattice extrinsic stacking fault energies or the anti-phase boundary energies, respectively, a consequence of the redistribution of charge density between Ti, Ta, Nb atoms and Ni atoms. [ABSTRACT FROM AUTHOR]

The prediction method of creep curve based on Zc parameter is proposed. The Zc parameter method is capable of effectively predicting creep curves and parameters (creep rate, minimum creep rate, and creep rupture life) under various experimental conditions, even with limited data. The predicted results are in accordance with experimental data, and all predictions are entirely within a 95% confidence interval, demonstrating the predictive reliability of the Zc method. Furthermore, on the premise of ensuring the accuracy of prediction, the setting of creep rupture strain for predicting creep rupture time using the Zc parameter method has a considerable range of options. Highlights: The creep curves predicted based on the Zc parameter method are good.Data scatter is considered and ±95% reliability is given.The creep parameters can be predicted by the Zc parameter method. [ABSTRACT FROM AUTHOR]

High‐temperature damage characteristics related to the deformation behavior of Sanicro 25 alloy were investigated under stress‐controlled cyclic loading. The results show that the strain curves exhibited creep‐like strain characteristics. The increase in mean stress increased the strain rate and weakened the life. Comparatively, the increase in stress amplitude only accelerated the tertiary‐regime strain rate, leading to a decrease in life and fracture strain. Microcrack initiation at grain boundaries and primary Z phases at different stress amplitudes can be evidenced by the observation of micro‐voids and high geometrically necessary dislocation densities around them. Subsequently, the increase in stress amplitude can significantly affect crack propagation. Dislocation accumulation at the transgranular crack tip caused by cyclic stress can assist the propagation of the transgranular crack at higher stress amplitude (σa=130MPa). Conversely, transgranular cracks are easily suppressed and stop propagating at grain boundaries under constant loading (σa=0MPa). The main reason was that the stress concentration of the transgranular crack tip at grain boundaries was dissipated through discontinuous dynamic recrystallization. Highlights: The HT damage evolution characteristics related mechanical response was investigated.Acceleration of creep‐dominated third‐regime strain rate by stress amplitude is revealed.The change of stress amplitude affected damage characteristics was discussed using EBSD.The cracking propagation mode was affected by the DDRX of transgranular crack tip at GBs. [ABSTRACT FROM AUTHOR]

The polished rod area and the lower thread of a Cd-plated and passivated stud assembled on a SEC (essential service water) pump in a nuclear power plant was corroded after being used for two months. The appearance and composition of the corroded stud were analyzed and a simulated assembly experiment was conducted. The results showed that the corrosion of the Cd-plated stud was mainly caused by combination of long-term exposure to seawater immersion and unsatisfactory quality of the Cd coating. Some suggestions for elimination of such problem were given. [ABSTRACT FROM AUTHOR]