Pub Date : 2025-02-15DOI: 10.1016/j.ijrmhm.2025.107099
Yuwei Ye , Baoshan Zhu , Luoyang Zheng , Zhihui Zhou , Yan Xue , Hao Chen , Zhuopeng Tan , Shufang Zhang
WC-based cemented carbides with different NbC amounts (0, 1, 2, 3, 4, and 5 wt%) were prepared by the liquid phase sintering method. When the NbC amount was low, it was uniformly distributed in the cemented carbide and reduced the grain size of WC grains. With the increase of NbC amount, the inhibitory effect of WC grain was weakened, and the (Nb, W)C solid solution was gradually formed. The hardness and impedance modulus (|Z|0.01Hz) of the cemented carbide increased to 1546 ± 7 kg/mm2 and 2200 ± 31 Ω cm2 at 2 wt% NbC. In addition, for additions of 2 wt% NbC, the corrosion current density (icorr) was 4.849 ± 0.5 × 10−6 A/cm2, the coefficient of friction (COF), 0.287 ± 0.004 and the lowest wear rate of 0.85 ± 0.03 × 10−5 mm3/(N⋅m) was observed. Therefore, the WC-based cemented carbides with 2 wt% NbC additive had the best comprehensive properties.
{"title":"Microstructure, mechanical, electrochemical and tribological performances of WC-based cemented carbides with different NbC amounts","authors":"Yuwei Ye , Baoshan Zhu , Luoyang Zheng , Zhihui Zhou , Yan Xue , Hao Chen , Zhuopeng Tan , Shufang Zhang","doi":"10.1016/j.ijrmhm.2025.107099","DOIUrl":"10.1016/j.ijrmhm.2025.107099","url":null,"abstract":"<div><div>WC-based cemented carbides with different NbC amounts (0, 1, 2, 3, 4, and 5 wt%) were prepared by the liquid phase sintering method. When the NbC amount was low, it was uniformly distributed in the cemented carbide and reduced the grain size of WC grains. With the increase of NbC amount, the inhibitory effect of WC grain was weakened, and the (Nb, W)C solid solution was gradually formed. The hardness and impedance modulus (|Z|<sub>0.01Hz</sub>) of the cemented carbide increased to 1546 ± 7 kg/mm<sup>2</sup> and 2200 ± 31 Ω cm<sup>2</sup> at 2 wt% NbC. In addition, for additions of 2 wt% NbC, the corrosion current density (i<sub>corr</sub>) was 4.849 ± 0.5 × 10<sup>−6</sup> A/cm<sup>2</sup>, the coefficient of friction (COF), 0.287 ± 0.004 and the lowest wear rate of 0.85 ± 0.03 × 10<sup>−5</sup> mm<sup>3</sup>/(N⋅m) was observed. Therefore, the WC-based cemented carbides with 2 wt% NbC additive had the best comprehensive properties.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"129 ","pages":"Article 107099"},"PeriodicalIF":4.2,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.ijrmhm.2025.107094
José Manuel Córdoba Gallego
A mechanically induced self-sustaining reaction was carried out to synthesize a Ti0.9Ta0.1C0.5N0.5/Co powdered cermets, and then they were sintered by spark plasma sintering. Microstructural parameters effects studied by image analysis, and chemical composition (studied by Rietveld analysis) on the microhardness, hardening rate, fracture toughness, transverse rupture strength, and Young's modulus were related to the sintering conditions. The optimization of the sintering conditions (1150 °C, 30 MPa, and 8 min' dwell time) drove to a homogeneous microstructure and outstanding mechanical properties. Also, the tantalum was suggested to influence the interfacial energies of the system, yielding a stronger hard phase skeleton.
{"title":"Spark plasma sintering influence on microstructure and mechanical properties of Ti:Ta/carbonitride ceramic matrix composites","authors":"José Manuel Córdoba Gallego","doi":"10.1016/j.ijrmhm.2025.107094","DOIUrl":"10.1016/j.ijrmhm.2025.107094","url":null,"abstract":"<div><div>A mechanically induced self-sustaining reaction was carried out to synthesize a Ti<sub>0.9</sub>Ta<sub>0.1</sub>C<sub>0.5</sub>N<sub>0.5</sub>/Co powdered cermets, and then they were sintered by spark plasma sintering. Microstructural parameters effects studied by image analysis, and chemical composition (studied by Rietveld analysis) on the microhardness, hardening rate, fracture toughness, transverse rupture strength, and Young's modulus were related to the sintering conditions. The optimization of the sintering conditions (1150 °C, 30 MPa, and 8 min' dwell time) drove to a homogeneous microstructure and outstanding mechanical properties. Also, the tantalum was suggested to influence the interfacial energies of the system, yielding a stronger hard phase skeleton.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"128 ","pages":"Article 107094"},"PeriodicalIF":4.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.ijrmhm.2025.107097
Song Huang , Huachen Liu , Liangcai Du , Lichao Gong , Yunqi Xie , Qianqian Kong , Zhenhua Yao
Selective laser melting (SLM) combined with post-processing is a common method for fabricating complex-shaped cermets components. This study utilized SLM-fabricated samples and employed vacuum sintering as a post-processing technique to investigate the effects of different post-processing temperatures (1350 °C, 1375 °C, 1400 °C, 1425 °C, 1450 °C) on the microstructure and mechanical properties of TiC-35 wt% Ni cermets. The results showed that using SLM printing parameters of 240 W laser power and 300 mm/s scanning speed produced well-formed samples. As the sintering temperature increased, the sintering mechanism gradually transitioned from solid-phase sintering to liquid-phase sintering. Relative density, hardness, bending strength, and fracture toughness showed a trend of first increasing and then decreasing. At 1400 °C, peak values were achieved: 97.7 % relative density, 82.7 HRA hardness, 901.8 MPa bending strength, and 8.72 MPa·m1/2 fracture toughness. Beyond this temperature, excessive grain growth and an increase in the brittle Ni3Ti phase led to a decline in mechanical properties. Vacuum sintering could be a promising post-processing technique for eliminating SLM-related defects and enhancing mechanical properties.
{"title":"Effects of different post-processing temperatures on the microstructure and mechanical properties of TiC-Ni cermets fabricated by selective laser melting","authors":"Song Huang , Huachen Liu , Liangcai Du , Lichao Gong , Yunqi Xie , Qianqian Kong , Zhenhua Yao","doi":"10.1016/j.ijrmhm.2025.107097","DOIUrl":"10.1016/j.ijrmhm.2025.107097","url":null,"abstract":"<div><div>Selective laser melting (SLM) combined with post-processing is a common method for fabricating complex-shaped cermets components. This study utilized SLM-fabricated samples and employed vacuum sintering as a post-processing technique to investigate the effects of different post-processing temperatures (1350 °C, 1375 °C, 1400 °C, 1425 °C, 1450 °C) on the microstructure and mechanical properties of TiC-35 wt% Ni cermets. The results showed that using SLM printing parameters of 240 W laser power and 300 mm/s scanning speed produced well-formed samples. As the sintering temperature increased, the sintering mechanism gradually transitioned from solid-phase sintering to liquid-phase sintering. Relative density, hardness, bending strength, and fracture toughness showed a trend of first increasing and then decreasing. At 1400 °C, peak values were achieved: 97.7 % relative density, 82.7 HRA hardness, 901.8 MPa bending strength, and 8.72 MPa·m<sup>1</sup>/<sup>2</sup> fracture toughness. Beyond this temperature, excessive grain growth and an increase in the brittle Ni<sub>3</sub>Ti phase led to a decline in mechanical properties. Vacuum sintering could be a promising post-processing technique for eliminating SLM-related defects and enhancing mechanical properties.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"128 ","pages":"Article 107097"},"PeriodicalIF":4.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.ijrmhm.2025.107096
Tongwei Zhang , Longwu Liu , Xue Jiang , Ying Liu , Yong Han
Tungsten heavy alloys (WHAs) hold extensive and promising application prospects in the defense industry as well as the aerospace filed because of their high melting point, high strength, and low thermal expansion coefficient. However, the grain size of WHAs prepared by conventional liquid phase sintering is coarse, which limits the further improvement of their mechanical properties. Designing high-entropy alloys (HEAs) as the binder phase provides a novel way to inhibit tungsten grain coarsening and improve the properties of WHAs due to the hysteresis diffusion effect of HEAs. In our previous research, a fine-grain and ultrahigh-strength WHA with non-equiatomic Ni5.5Fe2.5CoCr HEA as the binder phase was designed and successfully fabricated through the spark plasma sintering (SPS)method. In this study, vacuum heat treatment was adopted to further enhance the strength - toughness matching performance of the material. A systematic investigation was carried out on the impacts of the heat treatment process on the microstructure and mechanical properties of the 90W-Ni5.5Fe2.5CoCr alloy. The results show that the single - heat - treatment process exerts little influence on the microstructure and properties of 90 W-Ni5.5Fe2.5CoCr alloy. In contrast, the two - step heat - treatment process can remarkably optimize the distribution of the precipitated phases within the alloy. This optimization effectively enhances the plasticity of the alloy. Specifically, the fracture elongation can be increased from approximately 10 % to around 16 %. Moreover, it has been discovered that dislocations are predominantly distributed at the interface between the binder phase and the W phase. This distribution pattern is conducive to promoting the plastic - deformation capacity of the alloy.
{"title":"Effect of heat treatment on microstructure and mechanical properties of tungsten heavy alloy with a non-equiatomic Ni5.5Fe2.5CoCr high-entropy binder","authors":"Tongwei Zhang , Longwu Liu , Xue Jiang , Ying Liu , Yong Han","doi":"10.1016/j.ijrmhm.2025.107096","DOIUrl":"10.1016/j.ijrmhm.2025.107096","url":null,"abstract":"<div><div>Tungsten heavy alloys (WHAs) hold extensive and promising application prospects in the defense industry as well as the aerospace filed because of their high melting point, high strength, and low thermal expansion coefficient. However, the grain size of WHAs prepared by conventional liquid phase sintering is coarse, which limits the further improvement of their mechanical properties. Designing high-entropy alloys (HEAs) as the binder phase provides a novel way to inhibit tungsten grain coarsening and improve the properties of WHAs due to the hysteresis diffusion effect of HEAs. In our previous research, a fine-grain and ultrahigh-strength WHA with non-equiatomic Ni<sub>5.5</sub>Fe<sub>2.5</sub>CoCr HEA as the binder phase was designed and successfully fabricated through the spark plasma sintering (SPS)method. In this study, vacuum heat treatment was adopted to further enhance the strength - toughness matching performance of the material. A systematic investigation was carried out on the impacts of the heat treatment process on the microstructure and mechanical properties of the 90W-Ni<sub>5.5</sub>Fe<sub>2.5</sub>CoCr alloy. The results show that the single - heat - treatment process exerts little influence on the microstructure and properties of 90 W-Ni<sub>5.5</sub>Fe<sub>2.5</sub>CoCr alloy. In contrast, the two - step heat - treatment process can remarkably optimize the distribution of the precipitated phases within the alloy. This optimization effectively enhances the plasticity of the alloy. Specifically, the fracture elongation can be increased from approximately 10 % to around 16 %. Moreover, it has been discovered that dislocations are predominantly distributed at the interface between the binder phase and the W phase. This distribution pattern is conducive to promoting the plastic - deformation capacity of the alloy.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"128 ","pages":"Article 107096"},"PeriodicalIF":4.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.ijrmhm.2025.107095
Zhi Zhao, Xuan Yao, Chao Hou, Tielong Han, Erqi Yang, Xiaotong Zheng, Xinyu Li, Xiaoyan Song
Conventional fabrication methods for WCu composites possess several limitations on the ultimate densification and comprehensive performance of products. Here we propose an innovative protocol to prepare WCu via photochemical reactions at ambient conditions. Specifically engineered polymeric reagent guided the continuous growth of Cu within W matrix and enhanced the affinity among W/Cu phases, whose combination led to well densified WCu composite. Our strategy completely avoided thermally induced grain growth and flipped the immiscible nature of W/Cu interfaces. It was even possible to simultaneously fabricate and shape products using patterned light field. This strategy provides new insight on fabricating metallic composites.
{"title":"Photochemical fabrication of metallic composites: Synergize metal growth with interfacial bonding by polymers","authors":"Zhi Zhao, Xuan Yao, Chao Hou, Tielong Han, Erqi Yang, Xiaotong Zheng, Xinyu Li, Xiaoyan Song","doi":"10.1016/j.ijrmhm.2025.107095","DOIUrl":"10.1016/j.ijrmhm.2025.107095","url":null,"abstract":"<div><div>Conventional fabrication methods for W<img>Cu composites possess several limitations on the ultimate densification and comprehensive performance of products. Here we propose an innovative protocol to prepare W<img>Cu via photochemical reactions at ambient conditions. Specifically engineered polymeric reagent guided the continuous growth of Cu within W matrix and enhanced the affinity among W/Cu phases, whose combination led to well densified W<img>Cu composite. Our strategy completely avoided thermally induced grain growth and flipped the immiscible nature of W/Cu interfaces. It was even possible to simultaneously fabricate and shape products using patterned light field. This strategy provides new insight on fabricating metallic composites.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"128 ","pages":"Article 107095"},"PeriodicalIF":4.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.ijrmhm.2025.107093
S. Srinivasan, J. Gillham, J. Marshall
Cemented tungsten carbides (cWCs) and reactive sintered borides (RSB) are novel radiation-dense materials that are recent candidates as reactor shielding for compact spherical tokamaks (cST). This work investigates the use of pressure-less sinter-fusing methods for joining dissimilar materials for use in activating environments. Pressure-less sinter-fusing shows promise as a relatively non-invasive joining method for dissimilar materials, and it can be performed in an inert atmosphere or under vacuum. Sinter-fusing as a method for joining low-activation cWC and RSB materials to mild steels was investigated using various braze alloy mixtures as a paste and metal foils. A selection of low-activation braze alloys was investigated to join cWC and RSB to steel using sinter-fusing at 1300 °C in Ar for 2 h. Low-activating braze alloys were based on Cu and Fe as the major components with additions including Cr, Zr, Ti, C, B and Si as minor components. SEM-EDX was used to assess the quality of bonding and diffusion of the braze compounds post-sintering. The Vickers hardness mechanical test was carried out for the base materials and the joint interface, and the fracture toughness values were calculated from the hardness data. Results show that both brazing paste and foils have achieved well joints with no cracks and pores, but Cu foil-based joints shown superior to that of brazing paste concerning their mechanical properties.
{"title":"Low-activation joining methods for cWC and RSBs on steel for nuclear applications","authors":"S. Srinivasan, J. Gillham, J. Marshall","doi":"10.1016/j.ijrmhm.2025.107093","DOIUrl":"10.1016/j.ijrmhm.2025.107093","url":null,"abstract":"<div><div>Cemented tungsten carbides (cWCs) and reactive sintered borides (RSB) are novel radiation-dense materials that are recent candidates as reactor shielding for compact spherical tokamaks (cST). This work investigates the use of pressure-less sinter-fusing methods for joining dissimilar materials for use in activating environments. Pressure-less sinter-fusing shows promise as a relatively non-invasive joining method for dissimilar materials, and it can be performed in an inert atmosphere or under vacuum. Sinter-fusing as a method for joining low-activation cWC and RSB materials to mild steels was investigated using various braze alloy mixtures as a paste and metal foils. A selection of low-activation braze alloys was investigated to join cWC and RSB to steel using sinter-fusing at 1300 °C in Ar for 2 h. Low-activating braze alloys were based on Cu and Fe as the major components with additions including Cr, Zr, Ti, C, B and Si as minor components. SEM-EDX was used to assess the quality of bonding and diffusion of the braze compounds post-sintering. The Vickers hardness mechanical test was carried out for the base materials and the joint interface, and the fracture toughness values were calculated from the hardness data. Results show that both brazing paste and foils have achieved well joints with no cracks and pores, but Cu foil-based joints shown superior to that of brazing paste concerning their mechanical properties.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"129 ","pages":"Article 107093"},"PeriodicalIF":4.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.ijrmhm.2025.107092
Jian Yang , Shenghui Lu , Jijun Yang
NbMoVCrSix high-entropy alloy coatings with different Si contents were prepared, and the evolution in microstructure, mechanical properties, and wear behavior of the coatings was investigated comprehensively. The results showed that the coating structure transformed from the body-centered cubic phase to fully amorphous structure. With the trace Si doping, the hardness of the coating improved significantly, which was dominated by the effects of fine grain strengthening and solid solution strengthening. Meanwhile, the average friction coefficient and wear rate were decreased remarkably due to the improved hardness and toughness, and the formation of lubricating tribo-oxide layer containing SiO2. However, when Si doping was excessive, the comprehensive properties of the coating deteriorated seriously due to the reduced hardness and limited deformation ability.
{"title":"Variation of microstructure and mechanical properties of NbMoVCr high-entropy alloy coatings doped silicon","authors":"Jian Yang , Shenghui Lu , Jijun Yang","doi":"10.1016/j.ijrmhm.2025.107092","DOIUrl":"10.1016/j.ijrmhm.2025.107092","url":null,"abstract":"<div><div>NbMoVCrSi<sub>x</sub> high-entropy alloy coatings with different Si contents were prepared, and the evolution in microstructure, mechanical properties, and wear behavior of the coatings was investigated comprehensively. The results showed that the coating structure transformed from the body-centered cubic phase to fully amorphous structure. With the trace Si doping, the hardness of the coating improved significantly, which was dominated by the effects of fine grain strengthening and solid solution strengthening. Meanwhile, the average friction coefficient and wear rate were decreased remarkably due to the improved hardness and toughness, and the formation of lubricating tribo-oxide layer containing SiO<sub>2</sub>. However, when Si doping was excessive, the comprehensive properties of the coating deteriorated seriously due to the reduced hardness and limited deformation ability.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"128 ","pages":"Article 107092"},"PeriodicalIF":4.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1016/j.ijrmhm.2025.107091
Samuele Di Sturco , Giulio Marchese , Federica Bondioli , Mariangela Lombardi , Daniele Ugues , Paolo Fino , Sara Biamino
This work aims to develop and characterize molybdenum (Mo) processed by Electron Beam Powder Bed Fusion (EB-PBF). Two Mo powders with different oxygen levels were used to investigate the processability, obtaining crack-free bulk samples. The process parameter optimization resulted in a residual porosity of around 0.15 %, showing that limiting the oxygen played a key role in reducing the formation of pores. The as-fabricated Mo samples displayed columnar grains with lengths of several millimeters along the building direction composed of numerous subgrain structures created by the thermal stresses of the EB-PBF process. Moreover, the high preheating temperature, as well as the remelting combined with high residual stresses, triggered the formation of a few recrystallized grains. The Mo samples were characterized by a strong 〈001〉 crystallographic fiber orientation along the building direction. The microstructure also revealed the formation of a limited quantity of molybdenum oxides along the grain boundaries. Finally, the bending strength, hardness, Young modulus, and coefficient of thermal expansion (CTE) were determined. The Mo processed by EB-PBF presented bending strength superior to the traditional recrystallized Mo, while the Young modulus and CTE were compatible with the traditional processed Mo.
{"title":"Understanding the processability, microstructure, and mechanical properties of molybdenum processed by electron beam powder bed fusion","authors":"Samuele Di Sturco , Giulio Marchese , Federica Bondioli , Mariangela Lombardi , Daniele Ugues , Paolo Fino , Sara Biamino","doi":"10.1016/j.ijrmhm.2025.107091","DOIUrl":"10.1016/j.ijrmhm.2025.107091","url":null,"abstract":"<div><div>This work aims to develop and characterize molybdenum (Mo) processed by Electron Beam Powder Bed Fusion (EB-PBF). Two Mo powders with different oxygen levels were used to investigate the processability, obtaining crack-free bulk samples. The process parameter optimization resulted in a residual porosity of around 0.15 %, showing that limiting the oxygen played a key role in reducing the formation of pores. The as-fabricated Mo samples displayed columnar grains with lengths of several millimeters along the building direction composed of numerous subgrain structures created by the thermal stresses of the EB-PBF process. Moreover, the high preheating temperature, as well as the remelting combined with high residual stresses, triggered the formation of a few recrystallized grains. The Mo samples were characterized by a strong 〈001〉 crystallographic fiber orientation along the building direction. The microstructure also revealed the formation of a limited quantity of molybdenum oxides along the grain boundaries. Finally, the bending strength, hardness, Young modulus, and coefficient of thermal expansion (CTE) were determined. The Mo processed by EB-PBF presented bending strength superior to the traditional recrystallized Mo, while the Young modulus and CTE were compatible with the traditional processed Mo.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"129 ","pages":"Article 107091"},"PeriodicalIF":4.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-10DOI: 10.1016/j.ijrmhm.2025.107088
Lijun Jiang , Yong Liu , Shuailong Zhang , Ji Zhang , Wentao Liu , Huichao Cheng
Powder extrusion printing (PEP) of tungsten addresses the limitations of residual stress cracking and the high costs associated with direct 3D printing of powder materials. It shows significant potential for producing tungsten products with complex geometries. In this study, green parts made from fine and medium-sized tungsten powders were fabricated using PEP, followed by solvent-thermal debinding and vacuum sintering to create samples with varying densities. The rheological behavior of both feedstock, process parameters affecting print quality, solvent debinding, and microstructural evolution during sintering were investigated. The results indicate that the viscosity of fine tungsten powder feedstock is higher and more sensitive to temperature changes. Key factors influencing print quality include layer thickness, nozzle diameter, and printing speed. Solvent debinding progresses from the sample's edge towards its center, with the debinding rate primarily governed by solute dissolution and diffusion. After sintering at 1750 °C, the relative density of medium-sized tungsten powder reached only 74.0 %, whereas the fine powder achieved a density of 96.8 %. These findings confirm that extrusion 3D printing, combined with sintering, is an effective method for producing high-density tungsten parts with intricate shapes.
{"title":"Investigation of microstructural evolution and property optimization of pure tungsten via powder extrusion 3D printing","authors":"Lijun Jiang , Yong Liu , Shuailong Zhang , Ji Zhang , Wentao Liu , Huichao Cheng","doi":"10.1016/j.ijrmhm.2025.107088","DOIUrl":"10.1016/j.ijrmhm.2025.107088","url":null,"abstract":"<div><div>Powder extrusion printing (PEP) of tungsten addresses the limitations of residual stress cracking and the high costs associated with direct 3D printing of powder materials. It shows significant potential for producing tungsten products with complex geometries. In this study, green parts made from fine and medium-sized tungsten powders were fabricated using PEP, followed by solvent-thermal debinding and vacuum sintering to create samples with varying densities. The rheological behavior of both feedstock, process parameters affecting print quality, solvent debinding, and microstructural evolution during sintering were investigated. The results indicate that the viscosity of fine tungsten powder feedstock is higher and more sensitive to temperature changes. Key factors influencing print quality include layer thickness, nozzle diameter, and printing speed. Solvent debinding progresses from the sample's edge towards its center, with the debinding rate primarily governed by solute dissolution and diffusion. After sintering at 1750 °C, the relative density of medium-sized tungsten powder reached only 74.0 %, whereas the fine powder achieved a density of 96.8 %. These findings confirm that extrusion 3D printing, combined with sintering, is an effective method for producing high-density tungsten parts with intricate shapes.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"128 ","pages":"Article 107088"},"PeriodicalIF":4.2,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-04DOI: 10.1016/j.ijrmhm.2025.107090
Uttiyoarnab Saha , Santu Dey , Chethan Konkati , Apu Sarkar , Subarna Datta , Argha Dutta , Soumita Chakraborty , Ankur Chauhan , N. Gayathri , P. Mukherjee
This study investigates the effects of 7 MeV proton irradiation on the microstructure and mechanical properties of deformed molybdenum (Mo) through a combination of experimental techniques and molecular dynamics simulations. Microstructural characterization via X-ray Diffraction Line Profile Analysis (XRDLPA) revealed high microstrain and dislocation density in unirradiated samples, which decreased and eventually saturated with irradiation. Residual resistivity measurements indicated the formation of irradiation-induced defects that reduced the electron mean free path. Transmission Electron Microscopy (TEM) confirmed the presence of a deformed microstructure in the unirradiated state and revealed the formation and growth of dislocation loops with increasing irradiation dose. Tensile testing showed enhanced yield stress and plasticity in irradiated samples, with fracture surface analysis indicating a transition towards ductile fracture at higher doses. Molecular dynamics simulations corroborated the experimental findings, showing defect saturation at high doses and the formation of ½〈111〉 dislocations, predominantly of edge character. Enhanced ductility in irradiated pre-deformed samples was attributed to the ability of these dislocations and their segments to sustain efficient slip processes. This comprehensive study provides new insights into the dynamic interplay between irradiation-induced defects and mechanical behaviour in deformed Mo, with implications for its use in radiation environments.
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