As a critical strategic material for aero-engines and industrial gas turbines, the composition/process design, optimization and process control of superalloys remain at the core of industry concerns. The present work focuses on addressing practical challenges in the development and production of superalloys and their components. It identifies key influencing factors in typical processes within the manufacturing workflow and employs a combination of advanced characterization techniques such as synchrotron radiation and high-throughput experimental methods. This integrated approach enables the design and optimization of critical process parameters for superalloy manufacturing, thereby providing foundational support for enhancing process technology, product performance, research and development efficiency, and reducing costs. Taking representative manufacturing processes involving liquid-solid and solid-solid phase transformations as examples, we explore precision tailoring strategies and validation methods for key stages including master alloy melting/remelting, synergistic particle size/morphology control in gas atomization, shrinkage porosity control during casting solidification, powder storage/desorption treatments, powder consolidation through hot isostatic pressing（HIP） and heat treatment procedures. In addition, optimal usage conditions are investigated for auxiliary materials or consumables integral to superalloy production, particularly ceramics, isothermal forging dies and brazing repair materials. Notably, the research on process tailoring reveals significant phenomena: （1）the impact of oxygen existence forms in cast and powder metallurgy alloys; （2）the influence of the initial microstructural state of alloys on the phase transformation temperature during HIP consolidation and heat treatment; （3）the formation and control of abnormal phases and defects in cast, powder metallurgy and additive manufacturing alloys, along with repair materials for brazing and ceramic refractories. The aforementioned findings establish a theoretical foundation for optimizing and tailoring superalloy process parameters and achieving precise manufacturing control, while also providing feasible technical pathways for industrial implementation.

TiAl alloys have attracted much attention due to its excellent specific strength, specific stiffness, and high-temperature performance, which has great potential for application in the aerospace industry. With the development of aerospace technology, the performance requirements for its equipment and service materials have further increased. Thermomechanical treatment plays a very important role in the field of manufacturing technology of aerospace equipment. The mature preparation processes for TiAl alloys are mainly ingot metallurgy and powder metallurgy. TiAl alloys are obtained by both processes require subsequent thermomechanical treatment. Combining the processes of deformation with heat treatment, the microstructure of TiAl alloys can be effectively controlled, thereby improving the room-temperature brittleness and fracture toughness of alloys. On the basis of fully understanding the thermoplastic deformation behavior of TiAl alloys, further research on different hot working methods and processes, process parameter design and control of TiAl alloys are of great significance for reducing the processing cost of TiAl alloy products as well as promoting their production and application. This article mainly reviews the development status of thermomechanical treatment of TiAl alloys.The research progress in the thermoplastic deformation behavior as well as microstructure control of hotworking （hot forging, hot rolling, hot extrusion） and subsequent heat treatment of TiAl alloys is summarized. On the basis, this article proposes the development directions in thermomechanical treatment of TiAl alloys. The first is the research on thermomechanical treatment process of TiAl composite materials. On the basis of high-throughput material design, exploring the hot working and post-treatment process routes suitable for TiAl composites, is expected to develop a new type of TiAl material with excellent high-temperature comprehensive performance. The second is the optimization design of hot working process for large-sized TiAl alloy components. Combining machine learning methods to optimize the hot working parameters of large-sized TiAl alloy components, as well as predict the microstructure evolution during hot working, and developing new mold materials to effectively control the processing temperature, are expected to significantly improve the controllability and stability in the forming process of large-sized TiAl components. The third is the development of low-cost thermomechanical treatment technology of TiAl alloys, such as no package hot working technology and single-step heat treatment process. The fourth is the thermomechanical treatment control of new microstructures for TiAl alloys. On the basis of introducing nanostructures to refine the microstructure of TiAl alloys, a new type of TiAl alloy microstructure design is expected to carry out by thermomechanical treatment to further enhance the performance of TiAl alloys. The fifth is the efficient screening of thermomechanical treatment process parameters for TiAl alloys. Integrating multidisciplinary knowledge, constructing a large database of components, hot working/heat treatment parameters, microstructure, and properties, can reduce the costs and cycles of researches.

Optimizing the directional solidification process of nickel-based superalloys is pivotal for enhancing the quality of hot-end castings in aero-engines. Traditional process optimization methods have heavily relied on empirical trial-and-error approaches, whereas numerical simulation technology is increasingly emerging as a pivotal tool. This paper presents a comprehensive review of the latest advancements in numerical simulation pertaining to the directional solidification process of nickel-based superalloys. It emphasizes modeling methodologies, simulation outcomes, and their practical applications in process optimization and defect control（such as stray grains and freckles） across various multi-physics fields, encompassing temperature fields, fluid flow and solute transport, stress-strain fields, and microstructural aspects（grains and dendrites）. A synthesis of current research reveals that numerical simulation studies still grapple with several shortcomings: a high degree of dependence on approximate boundary conditions in models; inadequate refinement and limited global optimization capabilities within process windows; incomplete numerical representations of certain crystalline defects and complex defect interactions; and substantial computational resource demands for high-fidelity microstructural simulations. To tackle these challenges, future research trends are anticipated to concentrate on deepening and integrating multi-physics and cross-scale coupling models, leveraging artificial intelligence-driven simulation and optimization, enhancing the precise characterization of solidification mechanisms in multi-component alloys, and strengthening experimental-simulation collaborative validation systems through the integration of in-situ characterization techniques with simulations. By advancing in these areas, numerical simulation technology is poised to play a pivotal role in achieving precise control over the morphology and properties of complex castings, while effectively mitigating defects.

High-temperature high-entropy alloys（HEAs）show potential to surpass traditional Ni-based alloys through multi-principal element synergy and microstructural regulation. This review systematically examines three systems: high-entropy superalloys（HESAs）, refractory HEAs（RHEAs） and refractory high-entropy superalloys（RSAs）. HESAs emulate the γ/γ′ dual-phase structure of Ni-based alloys, achieving comparable strength at 800-1000 ℃. RHEAs utilize refractory elements to form high-melting-point solid solutions with superior performance above 1200 ℃. RSAs innovate with BCC/B2 nanobasket structures, outperforming Ni-based alloys across 25-1200 ℃. Current challenges include poor room-temperature ductility, oxidation resistance and phase stability, demanding breakthroughs in multi-scale microstructure control, dynamic phase transformation mechanisms and high-throughput design. Future directions prioritize multi-objective composition optimization, advanced processing, cross-scale characterization, and service-condition evaluation systems to guide extreme-environment applications like aeroengine components and nuclear reactors, etc.

IN718 superalloy is extensively utilized in the aerospace and nuclear industries due to its outstanding oxidation resistance, heat-corrosion resistance, good structural stability, fatigue performance and safety reliability. It is one of irreplaceable materials for the hot-end components of next-generation advanced aircraft engines. Recently, laser powder bed fusion（LPBF） technology has developed as an innovative rapid prototyping technique, transcending the limitations of traditional shaping methods and structural designs. This technology has realized one-step laser near-net shaping of complex thin-walled structures, demonstrating substantial application potential. However, during the laser additive manufacturing process, the thin-walled surfaces are exposed to high laser input energy, which can readily induce warping, deformation, and even cracking, significantly impacting the service performance of these structures. To address these challenges, this work provides an overview of the working principle and recent advancements in LPBF technologies. It systematically analyses the multi-scale microstructural evolution and precipitation phase behavior of IN718 superalloy thin wall fabricated by LPBF. Special emphasis is placed on the initiation, propagation mechanisms and mitigation strategies for metallurgical defects, including optimized thin-walled structural designs, laser forming process parameters and alloy composition. In addition, the strengthening mechanisms underlying the mechanical properties of IN718 superalloy thin wall at both room and high temperatures are analyzed and discussed. Finally, the work summarizes the existing challenges such as insufficient critical performance under harsh conditions and future development directions of superalloy thin wall fabricated by LPBF, including establishment of laser forming process databases specialized for superalloy thin wall, investigation of solidification defect formation and novel control strategies in superalloy thin wall fabricated by LPBF, and optimization of the chemical composition design for high-performance superalloy thin-walled components.

Traditionally, the creep performance of superalloys are characterized under isothermal and constant-stress conditions. However, in the service environments of aero-engines, internal cooling introduces notable through-thickness temperature gradients within turbine blade materials. Consequently, examining the creep behavior of single-crystal alloys under such temperature gradients holds considerable engineering significance. This study conducts a series of temperature-gradient creep experiments based on a Ni₃Al-based superalloy. Temperature gradients of 10⁵ K/m and 5×10⁴ K/m are imposed. The results indicate that temperature gradients exert a substantial influence on specimens creep rupture life. Specifically, compared to isothermal creep, the application of a 10⁵ K/m gradient leads to an almost 46% extension in creep life, whereas a 5×10⁴ K/m gradient results in about 30% improvement. Fractographic and microstructural analyses reveal enhanced anisotropy on the fracture surface under temperature gradients. Furthermore, the oxidation behavior varies markedly across different temperature zones: the high-temperature region exhibits a denser, thinner oxide layer, whereas the low-temperature region displays a porous, thicker oxide layer. In the 10⁵ K/m gradient specimen, the low-temperature area exhibits a rafted γ′ structure, while the high-temperature area shows a de-rafted morphology, suggesting differing strain rates between these regions.

Stress rupture tests are conducted on DD10 alloy specimens with two distinct wall thicknesses at conditions of 1000 ℃/200 MPa and 1100 ℃/100 MPa. The stress damage characteristics of these specimens and the reasons for the thin-wall effect are analysisd. The findings reveal that, under both test conditions, the stress rupture life of thinner specimens is markedly shorter compared to thicker ones, indicating a pronounced thin-wall effect in DD10 alloy. Although the reduction in effective bearing area due to oxidation does expedite the creep process to some extent, the variation in effective stress increase across different wall thicknesses is minimal, within a range of just 6%. This suggests that the augmentation in effective stress stemming from oxidation is not the primary catalyst behind the thin-wall effect. Microstructural observations of the surface and longitudinal sections of the fracture reveal that, under both test conditions, the cavities and cracks in thinner specimens are smaller in size than those in thicker specimens. Furthermore, the relationship between the stress intensity factor（K） and crack length（l） indicates that, for cracks of equivalent size in specimens with varying wall thicknesses, thinner specimens exhibit a higher stress intensity factor at the crack tip, rendering the crack more prone to propagation. Consequently, thinner specimens have a shorter critical size for crack instability expansion. The disparity in this critical size among specimens with different wall thicknesses is pinpointed as a crucial factor contributing to the thin-wall effect.

In order to investigate the effect of low-angle grain boundary（LAGB） on the high-temperature creep behavior of a second-generation nickel-based single-crystal（SX） superalloy, the high-temperature creep fracture and interrupted experiments are carried out at 1100 ℃/137 MPa using plate-shaped samples with different grain boundary misorientations. The results show that after standard heat treatment, fine MC carbides are formed at the LAGB with the misorientation of 7° in alloy GB-7, while blocky M₆C carbides are formed at the LAGB with the misorientation of 12° in alloy GB-12. The high temperature creep life of the investigated alloys decreases with increasing the misorientation degree. The creep life of alloy GB-12 is only 40% of that of the single crystal alloy. Further investigation reveals that LAGB migration occurrs in both the GB-7 and GB-12 alloys during high-temperature creep, but the migration distance of the GB-12 alloy is lower than that of the GB-7 alloy. Blocky M₆C carbides in alloy GB-12 hinder the grain boundary migration, leading to strain concentrations at the LAGB region. Cracks tend to initiate at the low-angle grain boundary either inside GB-12 alloy or on its surface, leading to a significant reduction in its creep life. This study can provide guidance and data support for improving the tolerance of LAGBs in high-temperature creep.

The creep properties of a corrosion resistant single crystal superalloy at 760 ℃/800 MPa, 980 ℃/250 MPa and 1120 ℃/130 MPa are investigated. The creep fracture microstructure, fracture characteristic and dislocation morphology under different conditions are analyzed using scanning electron microscopy（SEM）and transmission electron microscopy（TEM）. The results indicate that the alloy exhibits good creep performance at 760 ℃/800 MPa, 980 ℃/250 MPa and 1120 ℃/130 MPa, with its creep curves showing similar three-stage creep characteristics. As temperature increases and stress decreases, the creep lives of the initial and acceleration stages becomes shorter, while the creep life of the steady-state stage increases. Compared to 980 ℃/250 MPa and 1120 ℃/130 MPa, the creep rate during the initial stage is faster at 760 ℃/800 MPa. Under 760 ℃/800 MPa conditions, the γ′ phase retains its cuboidal morphology. The dislocation tangles forming in the matrix channels and stacking faults forming from some dislocation cutting γ′ phase have a reinforcing effect. The creep fracture morphology of the alloy involves cleavage-like and ductile dimple mixed fracture. At 980 ℃/250 MPa and 1120 ℃/130 MPa, the alloy exhibits obvious rafting behavior and topological inversion of γ′ phase and γ phase has finished. A high-density dislocation network forming at the γ/γ′ interfaces have a reinforcing effect. No stacking faults are observed to form. Dislocations cut into the γ′ phase during the later stage of creep.The creep fracture morphology is dominated by ductile dimple fracture. At 1120 ℃/130 MPa, a small amount of lamellar σ phases precipitate along specific directions in the alloy, indicating good microstructural stability.

To meet the lightweigh requirements, the structure of castings is evolving towards thin-walled designs. Therefore, it is necessary to study the evolution characteristics of the microstructures and mechanical properties of thin-walled structures made of nickel-based superalloys. Firstly, a thin-walled casting with wall thicknesses of 1, 1.25 mm and 1.5 mm is designed. Gravity casting experiments are conducted under two different process conditions, and the microstructural analysis and mechanical property tests are carried out for two types of castings, respectively. The values of microstructural characteristics are determined, including secondary dendrite arm spacing（SDAS）, grain morphology and average grain size, as well as the size and volume percentage of the γ′ phase at different wall thicknesses of the castings under different cooling conditions. The corresponding hardness and tensile strength also are measured by experiments. The results show that SDAS increases by more than 29.9% as the wall thickness of the casting increases from 1 mm to 1.25 mm and 1.5 mm. The tensile strength of the casting fluctuates with the increase in wall thickness when the flask temperature is 900 ℃. However, the tensile strength of the casting increases as the wall thickness increases when the flask temperature is 25 ℃. The variation range of the castings cooling rates are determined through numerical simulation. The cooling rate range of castings with a sand mold temperature of 900 ℃ ranges from 16.0 ℃/s to 28.2 ℃/s while those produced with a sand mold temperature of 25 ℃ exhibit a cooling rate range of 26.2 ℃/s to 58.5 ℃/s.

The directionally solidified superalloy DZ125 is widely used as turbine blades in aero-engines. This work investigates the influence of phosphorus（P）on the microstructure, mechanical properties and crack susceptibility of DZ125 alloy. The results indicate that P primarily segregates at grain boundaries in DZ125 alloy and has little effect on γ′ phases, γ+γ′ eutectic and carbides in the alloy. When P content reaches 0.008% （mass fraction, the same below） P-rich phases form in the interdendritic regions during casting, which subsequently dissolve back into the matrix during heat treatment.When the P content is no more than 0.0039%, P shows no obvious effects on the room-temperature tensile properties or the stress rupture life at 980℃/235 MPa. However, it has a significant impact on the stress rupture life at 760℃/805 MPa: the alloy with 0.0039% P exhibits a 37% decrease in stress rupture life at 760℃/805 MPa compared to the alloy with 0.0013% P, due to the segregation of P at grain boundaries weakens the grain boundaries. When the P content reaches 0.011%, the intergranular cracks appear in the DZ125 alloy hollow turbine blades during directionally solidified process. The main reason for the increase of crack susceptibility is excessive enrichment of P at grain boundaries and precipitation of P-rich phases nearby grain boundaries, which leads to grain boundary weakening and crack initiation.

Grain refinement can effectively enhance mechanical properties of materials at low and medium temperatures, however, it may weaken the stress rupture property above the equicohesive temperature. To study the effect of grain refinement on the stress rupture property of K447A alloy, the microstructure evolutions of alloys with three grain sizes and their corresponding stress rupture mechanisms under the conditions of 760 ℃/724 MPa, 815 ℃/600 MPa, 870 ℃/365 MPa and 980 ℃/210 MPa are investigated using scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results show that the equicohesive temperature of K447A alloy lies between 815 ℃ and 870 ℃. Grain refinement shows a temperature-dependent effect on the stress rupture life of K447A alloy. At 760 ℃/724 MPa, as the grain size decreases from 5.0 mm to 1.3 mm and then to 58 μm, the stress rupture life of K447A alloy increases from 83 h to 115 h and further to 194 h, respectively. At 815 ℃/600 MPa, the stress rupture life increases from 31 h to 84 h, as the grain size decreases, and then slightly drops to 76 h. At 870 ℃/365 MPa and 980 ℃/210 MPa, the stress rupture life shows a monotonic decreases with grain refinement. Therefore, grain refinement serves as an effective technology to improve the stress rupture property of K447A alloy below 870 ℃.The stress rupture process is dominated by intragranular deformation below 815 ℃, and grain refinement mainly extends the stress rupture life by shortening the slip band length and increasing the volume fraction of γ′ phase. Above 870 ℃, grain boundary sliding dominates the stress rupture process. The deterioration of the stress rupture property due to grain refinement can be attributed to the severe grain boundary slip at high temperatures, grain boundary oxidation and the formation of brittle AlN and a low-strength precipitation free zone（PFZ）.

Titanium alloy investment castings are widely used in the aerospace industry. During the manufacturing process, titanium is prone to reacting with the ceramic shell, which leads to defects such as shell cracking and casting deformation. Therefore, it is important to investigate the temperature distribution and deformation behavior during the sintering process of ceramic shell to improve the performance of the ceramic shell and enhancing the quality of casting. An advanced Monte Carlo method is employed to establish the radiative heat transfer model. Additionally, considering the impact of thermal damage, a coupled thermo-mechanical-damage constitutive model is established. A specialized simulation software is created through secondary development based on ABAQUS to investigate the sintering process of ceramic shell. Thermo-physical parameters of the ceramic shell are measured to provide data support for the simulations. The proposed models are experimentally validated using a flat-plate specimen, and experimental results agree well with the simulated outcomes. Using the developed software, a comprehensive study is conducted on the temperature distribution and deformation behavior of the ceramic shell in an annular-stepped specimen under various process schemes. The results indicate that a non-uniform temperature distribution during the sintering process is more likely to induce significant deformation and even cracking in the shells, particularly at structural protrusions. Moreover, as the sintering temperature rises, the decreased viscosity of the glassy phase in the ceramic shell will also intensify thermal stress accumulation and localized deformation. The simulation study on the temperature distribution and deformation behavior of the ceramic shell during the sintering process provides theoretical insights and technical support for optimizing the sintering process of the ceramic shell and improving the qualification rate of titanium alloy investment castings.

Based on the hot-ended casing of K4169 superalloy as the research object, aiming at the defects such as liquid splashing, oscillation and entrained air in the linear filling process of traditional superalloy counter-gravity casting, particularly, considering the complex variable cross-section structure of the casing castings, the work explores the influence of pressurization speed on filling of such structure through hydraulic simulation experiments. The results reveal that for the variable cross-section structure, a lower pressurization speed leads to more stable liquid filling. Orthogonal experiments are conducted to ascertain the optimal filling process parameter of the casing model such as a pouring temperature of 1460 ℃, a shell temperature of 900 ℃ and an average pressurization speed of 4 kPa/s. Based on the casing model’s structure, linear and nonlinear filling pressure curves are designed, and both numerical simulations and experimental studies are performed to compare two filling methods. When comparing two filling processes with the same filling time, the nonlinear filling exhibits a 16.77% decrease in average gate speed compared to the linear filling, resulting in a more stable filling process and production of fewer overall defects in the thin wall areas of the casing. Casings filled using the linear method exhibit numerous crack defects across various regions, leading to a relatively high overall defect rate. In contrast, casings filled using the nonlinear method devoid of crack defects and contain only a few micro-pores. Non-destructive testing results also support the notion that casing castings filled by the nonlinear method have fewer defects, which validates that the nonlinear filling effectively reduces the type and quantity of defects in casing castings.