Cover Story
- 2026
- 2025
- 2024
- 2023
2026, 55(5):1209-1215.
DOI: 10.12442/j.issn.1002-185X.20250197
Abstract:
Pu-Ga alloys are vital nuclear materials. However, the nucleation and growth of helium bubbles significantly affect their microstructural evolution and mechanical properties. In this work, a phase-field model was developed to simulate the formation and evolution of helium bubbles in Pu-Ga alloys during room-temperature aging. The model analyzed the morphological evolution of helium bubbles under different aging time and temperatures. According to phase-field simulation results, the variation curves of average diameter and number density of bubbles were obtained. The results show that at room temperature, bubble size and spatial distribution remain nearly unchanged, while the number density increases linearly. These simulation results align well with published experimental data. Further analysis indicates that aging temperature primarily affects growth kinetics of bubbles by influencing point defect mobility rate. In contrast, the exceptionally low diffusion coefficient at room temperature is the key factor leading to the unique evolution trends observed in bubble size and number density. This study provides a mesoscale theoretical model for accurately predicting the growth behavior of helium bubble in Pu-Ga alloys.
Pu-Ga alloys are vital nuclear materials. However, the nucleation and growth of helium bubbles significantly affect their microstructural evolution and mechanical properties. In this work, a phase-field model was developed to simulate the formation and evolution of helium bubbles in Pu-Ga alloys during room-temperature aging. The model analyzed the morphological evolution of helium bubbles under different aging time and temperatures. According to phase-field simulation results, the variation curves of average diameter and number density of bubbles were obtained. The results show that at room temperature, bubble size and spatial distribution remain nearly unchanged, while the number density increases linearly. These simulation results align well with published experimental data. Further analysis indicates that aging temperature primarily affects growth kinetics of bubbles by influencing point defect mobility rate. In contrast, the exceptionally low diffusion coefficient at room temperature is the key factor leading to the unique evolution trends observed in bubble size and number density. This study provides a mesoscale theoretical model for accurately predicting the growth behavior of helium bubble in Pu-Ga alloys.
2026, 55(4):1078-1089.
DOI: 10.12442/j.issn.1002-185X.20250305
Abstract:
Discontinuously reinforced titanium matrix composites (DRTMCs) exhibit advantages such as light weight, high strength, and heat resistance, demonstrating broad application prospects in aerospace, consumer electronics, and other fields. Inspired by the multi-scale architectures of natural materials, the design of DRTMCs has evolved from uniformly distributed single reinforcements to architecture reinforcement configurations, and further to the coordinated design and regulation of multi-scale reinforcement architectures coupled with hierarchical titanium matrix. This progression has enriched their microstructure, leading to the formation of multi-scale heterogeneous structures. Such structures fully leverage synergistic strengthening mechanisms to enhance strengthening efficiency. Moreover, these composites effectively avoid strain localization to ensure favorable plasticity while maintaining excellent damage resistance. This review summarizes typical configuration design strategies and their evolutionary pathways in DRTMCs, elucidates the underlying strengthening-toughening mechanisms, and proposes future research directions based on current advancements to advance the application of high-performance titanium matrix composites in critical fields.
Discontinuously reinforced titanium matrix composites (DRTMCs) exhibit advantages such as light weight, high strength, and heat resistance, demonstrating broad application prospects in aerospace, consumer electronics, and other fields. Inspired by the multi-scale architectures of natural materials, the design of DRTMCs has evolved from uniformly distributed single reinforcements to architecture reinforcement configurations, and further to the coordinated design and regulation of multi-scale reinforcement architectures coupled with hierarchical titanium matrix. This progression has enriched their microstructure, leading to the formation of multi-scale heterogeneous structures. Such structures fully leverage synergistic strengthening mechanisms to enhance strengthening efficiency. Moreover, these composites effectively avoid strain localization to ensure favorable plasticity while maintaining excellent damage resistance. This review summarizes typical configuration design strategies and their evolutionary pathways in DRTMCs, elucidates the underlying strengthening-toughening mechanisms, and proposes future research directions based on current advancements to advance the application of high-performance titanium matrix composites in critical fields.
2026, 55(3):665-673.
DOI: 10.12442/j.issn.1002-185X.20250081
Abstract:
To address the issues of rapid cooling rate during the solidification in underwater welding and the deterioration of the microstructure and properties, this work conducted local dry underwater welding experiments on 2205 duplex stainless steel using adjustable ring-mode laser. Meanwhile, compared with in-air welds, the effects of the power ratio between center and ring lasers on weld formation, microstructure and mechanical properties were investigated. The results show that the center laser mainly affects the penetration depth. With the increase in proportion of central power, the oxidation degree and surface roughness of the weld become more severe. In terms of microstructure, the underwater weld exhibits an increase in Widmanst?tten austenite content, but a decrease in or even disappearance of intragranular austenite, compared to welds produced with the same parameters in air. With the increase in proportion of ring laser, the austenite content in the weld shows no significant change, the grain size and aspect ratio of the weld decrease, the directionality of columnar crystal growth on both sides of the weld weakens, and the number of low-angle grain boundary increases. In terms of performance, the underwater joints exhibit slightly higher tensile strength but lower elongation than those welds in air. As the proportion of ring laser power increases from 1/3 to 2/3, the elongation of underwater joints increases by about 50%.
To address the issues of rapid cooling rate during the solidification in underwater welding and the deterioration of the microstructure and properties, this work conducted local dry underwater welding experiments on 2205 duplex stainless steel using adjustable ring-mode laser. Meanwhile, compared with in-air welds, the effects of the power ratio between center and ring lasers on weld formation, microstructure and mechanical properties were investigated. The results show that the center laser mainly affects the penetration depth. With the increase in proportion of central power, the oxidation degree and surface roughness of the weld become more severe. In terms of microstructure, the underwater weld exhibits an increase in Widmanst?tten austenite content, but a decrease in or even disappearance of intragranular austenite, compared to welds produced with the same parameters in air. With the increase in proportion of ring laser, the austenite content in the weld shows no significant change, the grain size and aspect ratio of the weld decrease, the directionality of columnar crystal growth on both sides of the weld weakens, and the number of low-angle grain boundary increases. In terms of performance, the underwater joints exhibit slightly higher tensile strength but lower elongation than those welds in air. As the proportion of ring laser power increases from 1/3 to 2/3, the elongation of underwater joints increases by about 50%.
2026, 55(2):345-364.
DOI: 10.12442/j.issn.1002-185X.20250370
Abstract:
Refractory metals, including tungsten (W), tantalum (Ta), molybdenum (Mo), and niobium (Nb), play a vital role in industries, such as nuclear energy and aerospace, owing to their exceptional melting temperatures, thermal durability, and corrosion resistance. These metals have body-centered cubic crystal structure, characterized by limited slip systems and impeded dislocation motion, resulting in significant low-temperature brittleness, which poses challenges for the conventional processing. Additive manufacturing technique provides an innovative approach, enabling the production of intricate parts without molds, which significantly improves the efficiency of material usage. This review provides a comprehensive overview of the advancements in additive manufacturing techniques for the production of refractory metals, such as W, Ta, Mo, and Nb, particularly the laser powder bed fusion. In this review, the influence mechanisms of key process parameters (laser power, scan strategy, and powder characteristics) on the evolution of material microstructure, the formation of metallurgical defects, and mechanical properties were discussed. Generally, optimizing powder characteristics, such as sphericity, implementing substrate preheating, and formulating alloying strategies can significantly improve the densification and crack resistance of manufactured parts. Meanwhile, strictly controlling the oxygen impurity content and optimizing the energy density input are also the key factors to achieve the simultaneous improvement in strength and ductility of refractory metals. Although additive manufacturing technique provides an innovative solution for processing refractory metals, critical issues, such as residual stress control, microstructure and performance anisotropy, and process stability, still need to be addressed. This review not only provides a theoretical basis for the additive manufacturing of high-performance refractory metals, but also proposes forward-looking directions for their industrial application.
Refractory metals, including tungsten (W), tantalum (Ta), molybdenum (Mo), and niobium (Nb), play a vital role in industries, such as nuclear energy and aerospace, owing to their exceptional melting temperatures, thermal durability, and corrosion resistance. These metals have body-centered cubic crystal structure, characterized by limited slip systems and impeded dislocation motion, resulting in significant low-temperature brittleness, which poses challenges for the conventional processing. Additive manufacturing technique provides an innovative approach, enabling the production of intricate parts without molds, which significantly improves the efficiency of material usage. This review provides a comprehensive overview of the advancements in additive manufacturing techniques for the production of refractory metals, such as W, Ta, Mo, and Nb, particularly the laser powder bed fusion. In this review, the influence mechanisms of key process parameters (laser power, scan strategy, and powder characteristics) on the evolution of material microstructure, the formation of metallurgical defects, and mechanical properties were discussed. Generally, optimizing powder characteristics, such as sphericity, implementing substrate preheating, and formulating alloying strategies can significantly improve the densification and crack resistance of manufactured parts. Meanwhile, strictly controlling the oxygen impurity content and optimizing the energy density input are also the key factors to achieve the simultaneous improvement in strength and ductility of refractory metals. Although additive manufacturing technique provides an innovative solution for processing refractory metals, critical issues, such as residual stress control, microstructure and performance anisotropy, and process stability, still need to be addressed. This review not only provides a theoretical basis for the additive manufacturing of high-performance refractory metals, but also proposes forward-looking directions for their industrial application.
2026, 55(1):105-115.
DOI: 10.12442/j.issn.1002-185X.20250150
Abstract:
Wire arc additive manufacturing (WAAM) holds significant application value in the aerospace field, but the instability of heat input leads to prominent issues such as poor geometric conformity and numerous internal defects in aluminum alloy thin-walled components. To address the restrictions of traditional methods in multi-physics coupling optimization, this study proposed a data-driven solution by constructing a dataset of process parameters (current, scanning speed and wire feed rate) and forming quality (path/interlayer wall thickness consistency and porosity). A back propagation (BP) neural network model was established and optimized using the genetic algorithm (GA), combined with the non-dominated sorting genetic algorithm II (NSGA-II) for multi-objective optimization. The results show that the optimized GA-BP model significantly improves the prediction accuracy of path wall thickness consistency and porosity, but its optimization effect on interlayer wall thickness consistency prediction is restricted. Four types of optimization strategies are proposed based on the 50 Pareto solution sets obtained through NSGA-II, and validation tests indicate the model prediction error of 8.89%, accurately achieving the collaborative optimization of forming quality indicators.
Wire arc additive manufacturing (WAAM) holds significant application value in the aerospace field, but the instability of heat input leads to prominent issues such as poor geometric conformity and numerous internal defects in aluminum alloy thin-walled components. To address the restrictions of traditional methods in multi-physics coupling optimization, this study proposed a data-driven solution by constructing a dataset of process parameters (current, scanning speed and wire feed rate) and forming quality (path/interlayer wall thickness consistency and porosity). A back propagation (BP) neural network model was established and optimized using the genetic algorithm (GA), combined with the non-dominated sorting genetic algorithm II (NSGA-II) for multi-objective optimization. The results show that the optimized GA-BP model significantly improves the prediction accuracy of path wall thickness consistency and porosity, but its optimization effect on interlayer wall thickness consistency prediction is restricted. Four types of optimization strategies are proposed based on the 50 Pareto solution sets obtained through NSGA-II, and validation tests indicate the model prediction error of 8.89%, accurately achieving the collaborative optimization of forming quality indicators.
2025, 54(12):2985-2992.
DOI: 10.12442/j.issn.1002-185X.20250168
Abstract:
The high-temperature mechanical properties of Ta-8W-2Hf alloy doped with Re (1wt%) and C (0.01wt%) were investigated at room temperature, 1300 °C, and 1500 °C. Results show that fine and dispersed precipitates Ta2C are detected in crystallized TaWHfReC alloy, which significantly enhance mechanical properties of the alloy. The strength of TaWHfReC alloy is much higher than that of TaWHf alloy, especially at 1300 and 1500 °C. At 1300 °C, the ultimate tensile strength of the TaWHf alloy is 322 MPa, while that of the TaWHfReC alloy reaches 392 MPa. When the temperature rises to 1500 °C, precipitated-phase strengthening remains effective in the TaWHfReC alloy, achieving an ultimate tensile strength of 268 MPa. Additionally, at 1300 °C, the elongation of the TaWHfReC alloy reaches 23.5%, which is nearly twice of that of the TaWHf alloy. The significant improvement in the mechanical properties of the TaWHfReC alloy at elevated temperatures is primarily attributed to the interaction between dislocations and the fine Ta2C precipitated phase. The fine and uniformly distributed particles effectively inhibit dislocation motion and exhibit a pronounced strengthening effect at high temperatures.
The high-temperature mechanical properties of Ta-8W-2Hf alloy doped with Re (1wt%) and C (0.01wt%) were investigated at room temperature, 1300 °C, and 1500 °C. Results show that fine and dispersed precipitates Ta2C are detected in crystallized TaWHfReC alloy, which significantly enhance mechanical properties of the alloy. The strength of TaWHfReC alloy is much higher than that of TaWHf alloy, especially at 1300 and 1500 °C. At 1300 °C, the ultimate tensile strength of the TaWHf alloy is 322 MPa, while that of the TaWHfReC alloy reaches 392 MPa. When the temperature rises to 1500 °C, precipitated-phase strengthening remains effective in the TaWHfReC alloy, achieving an ultimate tensile strength of 268 MPa. Additionally, at 1300 °C, the elongation of the TaWHfReC alloy reaches 23.5%, which is nearly twice of that of the TaWHf alloy. The significant improvement in the mechanical properties of the TaWHfReC alloy at elevated temperatures is primarily attributed to the interaction between dislocations and the fine Ta2C precipitated phase. The fine and uniformly distributed particles effectively inhibit dislocation motion and exhibit a pronounced strengthening effect at high temperatures.
