Pub Date : 2024-11-19DOI: 10.1016/j.matchar.2024.114559
Stefano Felicioni , Elisa Padovano , Federica Bondioli , Paolo Fino
An in-depth characterization of microstructure and mechanical properties of CuCrZr alloy processed by electron beam powder bed fusion (EB-PBF) additive manufacturing technology was performed with the aim to investigate the effect the thermal history of the material during the building process has on the properties of printed parts. Fully dense samples with a relative density up to 99.77 ± 0.04 % were successfully obtained in optimized conditions. The samples in the as-built condition exhibit an anisotropic microstructure dependent on the energetic input. An extensive microstructural transformation occurs alongside the precipitation and segregation of chromium-rich species, driven by the elevated thermal conditions during the deposition process. This unique thermal evolution can be properly investigated and exploited to eliminate the need for further post-processing heat treatments. To identify and quantify the precipitations within the microstructure, scanning and transmission electron microscopy together with electron backscattered diffraction were used.
{"title":"CuCrZr alloy obtained via electron-beam powder bed fusion: Microstructural insights and precipitation behaviour","authors":"Stefano Felicioni , Elisa Padovano , Federica Bondioli , Paolo Fino","doi":"10.1016/j.matchar.2024.114559","DOIUrl":"10.1016/j.matchar.2024.114559","url":null,"abstract":"<div><div>An in-depth characterization of microstructure and mechanical properties of CuCrZr alloy processed by electron beam powder bed fusion (EB-PBF) additive manufacturing technology was performed with the aim to investigate the effect the thermal history of the material during the building process has on the properties of printed parts. Fully dense samples with a relative density up to 99.77 ± 0.04 % were successfully obtained in optimized conditions. The samples in the as-built condition exhibit an anisotropic microstructure dependent on the energetic input. An extensive microstructural transformation occurs alongside the precipitation and segregation of chromium-rich species, driven by the elevated thermal conditions during the deposition process. This unique thermal evolution can be properly investigated and exploited to eliminate the need for further post-processing heat treatments. To identify and quantify the precipitations within the microstructure, scanning and transmission electron microscopy together with electron backscattered diffraction were used.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114559"},"PeriodicalIF":4.8,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723138","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 : 2024-11-18DOI: 10.1016/j.matchar.2024.114567
L.S. Toth , W. Skrotzki , A. Pukenas , Yu. Ivanisenko , N. Yazbek
Nano-sized powder composed of single crystals of an Au-13 at.%Pd alloy was produced by inert gas condensation (IGC). Uniaxial compaction of the powder was applied in two stages: already within the IGC chamber at 2 GPa pressure, followed by another compaction stage at 6 GPa, outside the chamber. This processing resulted in a weak 〈110〉 fiber texture of the compressed alloy. The crystallographic texture formation during compaction was simulated using different polycrystal plasticity models. The experimental texture evolution was faithfully reproduced using the relaxed constraints polycrystal plasticity model complemented with a grain boundary sliding approach.
{"title":"Texture formation during compaction of nanocrystalline metal powder","authors":"L.S. Toth , W. Skrotzki , A. Pukenas , Yu. Ivanisenko , N. Yazbek","doi":"10.1016/j.matchar.2024.114567","DOIUrl":"10.1016/j.matchar.2024.114567","url":null,"abstract":"<div><div>Nano-sized powder composed of single crystals of an Au-13 at.%Pd alloy was produced by inert gas condensation (IGC). Uniaxial compaction of the powder was applied in two stages: already within the IGC chamber at 2 GPa pressure, followed by another compaction stage at 6 GPa, outside the chamber. This processing resulted in a weak 〈110〉 fiber texture of the compressed alloy. The crystallographic texture formation during compaction was simulated using different polycrystal plasticity models. The experimental texture evolution was faithfully reproduced using the relaxed constraints polycrystal plasticity model complemented with a grain boundary sliding approach.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114567"},"PeriodicalIF":4.8,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723131","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 : 2024-11-17DOI: 10.1016/j.matchar.2024.114562
Xiangnan Feng , Mingtao Zhang , Tao Jiang , Yunfei Xie , Zhonggang Sun , Wenya Li
Additive Friction Stir Deposition (AFSD), an emerging solid-based additive manufacturing technology, has demonstrated significant potential in the fabrication of high-strength aluminum alloys. In this study, a 22 mm thick 2024 aluminum alloy deposit having ten layers was for the first time successfully fabricated using the AFSD technique. The correlation between the microstructure evolution and mechanical properties within the deposit was revealed. The results indicated that the deposit exhibited very fine recrystallized microstructure and excellent mechanical properties. Dynamic recrystallization occurred with the average grain sizes at the top, center, and bottom of the deposit being 3.0 μm, 4.7 μm, and 4.8 μm, respectively. The Al2CuMg (S phase) at grain boundaries of the deposit was observed to fracture due to the plastic deformation of the feedstock during the deposition process. The Vickers hardness of the deposit cross-section along the build direction (BD) changed from 125 HV of the top to 85 HV of the bottom. Better tensile properties in the TD compared to the BD were observed with the excellent tensile strength of 532 MPa and 473 MPa, and the elongation of 31.2 % and 15.2 %, respectively. The synergistically improvement of the tensile strength and elongation in the TD was attributed to the uniform microstructure and mechanical properties exhibited by each deposit layer.
{"title":"Additive friction stir deposition of an Al-Cu-Mg alloy: Microstructure evolution and mechanical properties","authors":"Xiangnan Feng , Mingtao Zhang , Tao Jiang , Yunfei Xie , Zhonggang Sun , Wenya Li","doi":"10.1016/j.matchar.2024.114562","DOIUrl":"10.1016/j.matchar.2024.114562","url":null,"abstract":"<div><div>Additive Friction Stir Deposition (AFSD), an emerging solid-based additive manufacturing technology, has demonstrated significant potential in the fabrication of high-strength aluminum alloys. In this study, a 22 mm thick 2024 aluminum alloy deposit having ten layers was for the first time successfully fabricated using the AFSD technique. The correlation between the microstructure evolution and mechanical properties within the deposit was revealed. The results indicated that the deposit exhibited very fine recrystallized microstructure and excellent mechanical properties. Dynamic recrystallization occurred with the average grain sizes at the top, center, and bottom of the deposit being 3.0 μm, 4.7 μm, and 4.8 μm, respectively. The Al<sub>2</sub>CuMg (S phase) at grain boundaries of the deposit was observed to fracture due to the plastic deformation of the feedstock during the deposition process. The Vickers hardness of the deposit cross-section along the build direction (BD) changed from 125 HV of the top to 85 HV of the bottom. Better tensile properties in the TD compared to the BD were observed with the excellent tensile strength of 532 MPa and 473 MPa, and the elongation of 31.2 % and 15.2 %, respectively. The synergistically improvement of the tensile strength and elongation in the TD was attributed to the uniform microstructure and mechanical properties exhibited by each deposit layer.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114562"},"PeriodicalIF":4.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723690","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 : 2024-11-17DOI: 10.1016/j.matchar.2024.114548
Shuyao Liu , Xibin Wang , Hongtao Chen , Pai Wang , Zhibing Liu
Surface materials endure significant mechanical and thermal loads during machining, leading to microstructural changes and the formation of metamorphic layers. These layers exhibit altered crystallographic characteristics, such as grain size, misorientation angles, and dislocation density, resulting in mechanical properties that differ from the bulk material. This study examines the microstructural evolution of the metamorphic layer using electron back-scattered diffraction (EBSD) and X-ray diffraction (XRD). Based on microstructure characterization, a 3D reconstruction method was developed using a representative volume element (RVE). The crystal plasticity finite element method (CPFEM) was employed to establish the relationship between the microstructure and micromechanical properties, including microhardness, elastic modulus, and yield stress. The proposed method was validated by comparing simulation results with experimental data obtained from micro-pillar compression tests and nanoindentation tests. The results demonstrated a strong correlation in stress-strain curves, and the microhardness measurement error at indentation depths of 400 nm was less than 10 %.
{"title":"Investigation on micro-mechanics properties of machined metamorphic layer based on crystal plasticity finite element method","authors":"Shuyao Liu , Xibin Wang , Hongtao Chen , Pai Wang , Zhibing Liu","doi":"10.1016/j.matchar.2024.114548","DOIUrl":"10.1016/j.matchar.2024.114548","url":null,"abstract":"<div><div>Surface materials endure significant mechanical and thermal loads during machining, leading to microstructural changes and the formation of metamorphic layers. These layers exhibit altered crystallographic characteristics, such as grain size, misorientation angles, and dislocation density, resulting in mechanical properties that differ from the bulk material. This study examines the microstructural evolution of the metamorphic layer using electron back-scattered diffraction (EBSD) and X-ray diffraction (XRD). Based on microstructure characterization, a 3D reconstruction method was developed using a representative volume element (RVE). The crystal plasticity finite element method (CPFEM) was employed to establish the relationship between the microstructure and micromechanical properties, including microhardness, elastic modulus, and yield stress. The proposed method was validated by comparing simulation results with experimental data obtained from micro-pillar compression tests and nanoindentation tests. The results demonstrated a strong correlation in stress-strain curves, and the microhardness measurement error at indentation depths of 400 nm was less than 10 %.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114548"},"PeriodicalIF":4.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723134","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 : 2024-11-17DOI: 10.1016/j.matchar.2024.114560
Shihua Xiang , Xiaofang Yang , Lu Wang , Youcai Qiu , Jingxiao Li , Yanxiang Liang
CuNb nanocomposite wires prepared by accumulative drawing and bundling (ADB) exhibit multiscale microstructures: the size of Cu ranges from micrometer to nanometer, and Nb is nano-scale. In this work, Electron backscattering diffraction (EBSD) and precession electron diffraction (PED) are used to characterize the textures of micron−/submicron-scale and nano-scale Cu (Nb), respectively. The results indicate that the texture of Cu at different size scales varies significantly. Micron- and submicron-scale Cu shows noticeable texture gradients along the radial direction of wires, whereas nano-scale Cu and Nb fibers have homogeneously distributed textures. Micron-scale Cu has a 〈111〉 texture in wire center region and a random texture in edge; submicron-scale Cu develops a strong 〈100〉 texture in center and a < 111> texture in edge region; nano-scale Cu and Nb fibers exhibit strong 〈111〉 and 〈110〉 textures throughout the wire, respectively. Dynamic recrystallization during deformation leads to weakening of the texture strength in micron-scale Cu, while almost negligible effects on the texture of submicron- and nano-scale Cu/Nb due to the size and interface effects.
{"title":"Size effect on texture of multiscale Cu in CuNb nanocomposite wires","authors":"Shihua Xiang , Xiaofang Yang , Lu Wang , Youcai Qiu , Jingxiao Li , Yanxiang Liang","doi":"10.1016/j.matchar.2024.114560","DOIUrl":"10.1016/j.matchar.2024.114560","url":null,"abstract":"<div><div>Cu<img>Nb nanocomposite wires prepared by accumulative drawing and bundling (ADB) exhibit multiscale microstructures: the size of Cu ranges from micrometer to nanometer, and Nb is nano-scale. In this work, Electron backscattering diffraction (EBSD) and precession electron diffraction (PED) are used to characterize the textures of micron−/submicron-scale and nano-scale Cu (Nb), respectively. The results indicate that the texture of Cu at different size scales varies significantly. Micron- and submicron-scale Cu shows noticeable texture gradients along the radial direction of wires, whereas nano-scale Cu and Nb fibers have homogeneously distributed textures. Micron-scale Cu has a 〈111〉 texture in wire center region and a random texture in edge; submicron-scale Cu develops a strong 〈100〉 texture in center and a < 111> texture in edge region; nano-scale Cu and Nb fibers exhibit strong 〈111〉 and 〈110〉 textures throughout the wire, respectively. Dynamic recrystallization during deformation leads to weakening of the texture strength in micron-scale Cu, while almost negligible effects on the texture of submicron- and nano-scale Cu/Nb due to the size and interface effects.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114560"},"PeriodicalIF":4.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723139","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 : 2024-11-17DOI: 10.1016/j.matchar.2024.114558
Kewei Li , Huansheng He , Jingwen Zhang , Liming Yu , Tianyu Du , Qiuzhi Gao , Chenxi Liu , Huijun Li , Yongchang Liu , Yuehua Liu , Baoxin Du
Cu-alloyed martensitic heat-resistant steels are considered promising structural materials in advanced ultra-supercritical (USC) plants. In this work, the evolution of Cu-rich particles (CRPs) and Laves phases (LPs) in the G115 steel and the corresponding effects on microstructure recovery were systematically studied via interrupted creep. Most CRPs precipitated within the lath interior during tempering process and started to precipitate along the lath boundaries during creep. The interior-precipitated CRPs were gradually decomposed due to dislocation cutting effect, resulting in the decrease of their number density. The precipitation of CRPs along the lath boundaries could induce the heterogeneous precipitation of LPs owing to the decrease of nucleation barrier. The number density of LPs rapidly increased during the transient stage but started to decrease during the steady-stage stage due to the coarsening behaviors of Ostwald ripening and swallowing adjacent M23C6 particles. The larger size and decreased number density of LPs and CRPs considerably weakened their pinning force for dislocations and boundaries, leading to an intense microstructure recovery during the accelerated stage. Eventually, the large area of recrystallized grains and subgrains with low hardness and the accumulation of cavities resulted in the creep fracture.
{"title":"Evolution of Cu-rich particles and Laves phases in a novel Cu-alloyed martensitic heat-resistant steel during interrupted creep and the corresponding effects on microstructural recovery","authors":"Kewei Li , Huansheng He , Jingwen Zhang , Liming Yu , Tianyu Du , Qiuzhi Gao , Chenxi Liu , Huijun Li , Yongchang Liu , Yuehua Liu , Baoxin Du","doi":"10.1016/j.matchar.2024.114558","DOIUrl":"10.1016/j.matchar.2024.114558","url":null,"abstract":"<div><div>Cu-alloyed martensitic heat-resistant steels are considered promising structural materials in advanced ultra-supercritical (USC) plants. In this work, the evolution of Cu-rich particles (CRPs) and Laves phases (LPs) in the G115 steel and the corresponding effects on microstructure recovery were systematically studied via interrupted creep. Most CRPs precipitated within the lath interior during tempering process and started to precipitate along the lath boundaries during creep. The interior-precipitated CRPs were gradually decomposed due to dislocation cutting effect, resulting in the decrease of their number density. The precipitation of CRPs along the lath boundaries could induce the heterogeneous precipitation of LPs owing to the decrease of nucleation barrier. The number density of LPs rapidly increased during the transient stage but started to decrease during the steady-stage stage due to the coarsening behaviors of Ostwald ripening and swallowing adjacent M<sub>23</sub>C<sub>6</sub> particles. The larger size and decreased number density of LPs and CRPs considerably weakened their pinning force for dislocations and boundaries, leading to an intense microstructure recovery during the accelerated stage. Eventually, the large area of recrystallized grains and subgrains with low hardness and the accumulation of cavities resulted in the creep fracture.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114558"},"PeriodicalIF":4.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723691","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 : 2024-11-17DOI: 10.1016/j.matchar.2024.114557
Jun Takahashi , Kazuto Kawakami , Shinya Teramoto
The hydrogen trapping sites associated with epsilon carbide (ε-carbide) and cementite precipitates in high‑silicon martensitic steels tempered at different temperatures were investigated by direct observation using atom probe tomography (APT) combined with a deuterium charging method. Charged deuterium was obviously trapped within film-like ε-carbide precipitates in steel tempered at 400 °C. In contrast, no charged deuterium was observed in fine spheroidal cementite precipitates in steel tempered at 500 °C. However, in undeformed pearlitic steel, deuterium was weakly segregated at/near the lamellar cementite/ferrite interface. First-principles calculations have predicted that both ε-carbide and cementite have stable sites for hydrogen within their carbides, but diffusion barriers for hydrogen are too high to reach these sites. APT analysis indicated that the undeformed cementite (Fe3C) has a stoichiometric carbon composition of 25 at. % without carbon vacancies, whereas ε-carbide has much lower carbon concentrations than the stoichiometric composition (Fe2C), indicating high concentrations of carbon vacancies in ε-carbide. The high concentrations of carbon vacancies increased stable sites in ε-carbide and facilitated hydrogen diffusion by providing low-barrier diffusion pathways, enhancing its hydrogen-trapping ability. The difference in hydrogen trapping behavior between the two carbides is therefore attributed to the presence or absence of low-barrier diffusion pathways in the carbides, driven by the high concentrations of carbon vacancies.
通过原子探针层析成像（APT）直接观察结合氘充电法，研究了在不同温度下回火的高硅马氏体钢中与ε-碳化物（ε-carbide）和雪明碳化物沉淀相关的氢捕获位点。在 400 °C 回火的钢中，带电氘被明显地截留在薄膜状的ε-碳化物沉淀中。相反，在 500 °C 回火的钢中，细小的球状雪明碳化物沉淀中未观察到带电氘。不过，在未变形的珠光体钢中，氘在片状雪明碳化物/铁素体界面处或附近有弱偏析。第一性原理计算预测，ε-碳化物和雪明碳酸盐在其碳化物中都有氢的稳定位点，但氢的扩散障碍太高，无法到达这些位点。APT 分析表明，未变形的雪明碳化物（Fe3C）的化学计量碳成分为 25%，不含碳空位，而ε-碳化物的碳浓度远低于化学计量碳成分（Fe2C），表明ε-碳化物中存在高浓度的碳空位。高浓度的碳空位增加了ε-碳化物中的稳定位点，并通过提供低阻扩散途径促进了氢扩散，从而提高了其捕氢能力。因此，两种碳化物在捕氢行为上的差异可归因于碳化物中是否存在由高浓度碳空位驱动的低势垒扩散途径。
{"title":"Difference in hydrogen trapping behaviors between epsilon carbide and cementite in steels","authors":"Jun Takahashi , Kazuto Kawakami , Shinya Teramoto","doi":"10.1016/j.matchar.2024.114557","DOIUrl":"10.1016/j.matchar.2024.114557","url":null,"abstract":"<div><div>The hydrogen trapping sites associated with epsilon carbide (ε-carbide) and cementite precipitates in high‑silicon martensitic steels tempered at different temperatures were investigated by direct observation using atom probe tomography (APT) combined with a deuterium charging method. Charged deuterium was obviously trapped within film-like ε-carbide precipitates in steel tempered at 400 °C. In contrast, no charged deuterium was observed in fine spheroidal cementite precipitates in steel tempered at 500 °C. However, in undeformed pearlitic steel, deuterium was weakly segregated at/near the lamellar cementite/ferrite interface. First-principles calculations have predicted that both ε-carbide and cementite have stable sites for hydrogen within their carbides, but diffusion barriers for hydrogen are too high to reach these sites. APT analysis indicated that the undeformed cementite (Fe<sub>3</sub>C) has a stoichiometric carbon composition of 25 at. % without carbon vacancies, whereas ε-carbide has much lower carbon concentrations than the stoichiometric composition (Fe<sub>2</sub>C), indicating high concentrations of carbon vacancies in ε-carbide. The high concentrations of carbon vacancies increased stable sites in ε-carbide and facilitated hydrogen diffusion by providing low-barrier diffusion pathways, enhancing its hydrogen-trapping ability. The difference in hydrogen trapping behavior between the two carbides is therefore attributed to the presence or absence of low-barrier diffusion pathways in the carbides, driven by the high concentrations of carbon vacancies.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114557"},"PeriodicalIF":4.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723137","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}
This article addresses advanced high-strength Ni-Cr-Mo-V steels developed by different processing routes. First, three preliminary microstructures containing ferrite-pearlite, ferrite-martensite, and fully martensitic were made. These microstructures were also subjected to the cold-rolling with a 25 % thickness reduction. Ultimately, intercritical treatment (IT) was performed on non-deformed and deformed preliminary microstructures at a given temperature and time. The phase characterization through optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), and electron backscattered diffraction (EBSD) revealed a fine-tuned microstructure in the intercritically treated steel with non-deformed fully martensitic preliminary microstructure. There were lath-like ferrite with a finer size, lath-like new martensite, tempered martensite, higher geometrically necessary dislocations (GNDs) density, and a higher fraction of coincident site lattice boundaries (CSLBs) in this steel. Such formed microstructure could well tailor mechanical performance and lead to achieving the best strength-elongation-toughness synergy. At this condition, yield strength, ultimate tensile strength, elongation, tensile toughness, and Charpy impact energy were 1205±31 MPa, 1366±33 MPa, 13.1±1.0 %, 168.4±11.0 MJ/m3, and 83±5 J, respectively. It was found that the steel with a cold-rolled fully martensitic microstructure consisted of a complex microstructure after IT among the intercritically treated steels with deformed preliminary microstructures. Ultra-fine ferrite with lath and polygonal morphologies, lath-like martensite, blocky-like martensite, higher GNDs density, and more fraction of CSLBs were detected in this steel. Such a complex microstructure attained extraordinary strength-elongation-toughness synergy. Yield strength, ultimate tensile strength, elongation, tensile toughness, and Charpy impact energy equaled 1175±19 MPa, 1402±25 MPa, 11.7±0.4 %, 150.8±13.0 MJ/m3, and 102±2 J, respectively. Dimple and cleavage features were observed in the fracture surfaces of all intercritically treated steels after performing uniaxial tensile and Charpy impact tests at the room temperature. Failure and toughening mechanisms were comprehensively discussed, as well.
{"title":"Developing advanced high strength Ni-Cr-Mo-V steels with a superlative strength-elongation-toughness synergy through different processing routes","authors":"Farzad Badkoobeh , Shahram Raygan , Jafar Rassizadehghani , Tae-Yang Kwak , Bong-Hwan Kim","doi":"10.1016/j.matchar.2024.114556","DOIUrl":"10.1016/j.matchar.2024.114556","url":null,"abstract":"<div><div>This article addresses advanced high-strength Ni-Cr-Mo-V steels developed by different processing routes. First, three preliminary microstructures containing ferrite-pearlite, ferrite-martensite, and fully martensitic were made. These microstructures were also subjected to the cold-rolling with a 25 % thickness reduction. Ultimately, intercritical treatment (IT) was performed on non-deformed and deformed preliminary microstructures at a given temperature and time. The phase characterization through optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), and electron backscattered diffraction (EBSD) revealed a fine-tuned microstructure in the intercritically treated steel with non-deformed fully martensitic preliminary microstructure. There were lath-like ferrite with a finer size, lath-like new martensite, tempered martensite, higher geometrically necessary dislocations (GNDs) density, and a higher fraction of <span><math><mo>∑</mo><mn>3</mn></math></span> coincident site lattice boundaries (CSLBs) in this steel. Such formed microstructure could well tailor mechanical performance and lead to achieving the best strength-elongation-toughness synergy. At this condition, yield strength, ultimate tensile strength, elongation, tensile toughness, and Charpy impact energy were 1205±31 MPa, 1366±33 MPa, 13.1±1.0 %, 168.4±11.0 MJ/m<sup>3</sup>, and 83±5 J, respectively. It was found that the steel with a cold-rolled fully martensitic microstructure consisted of a complex microstructure after IT among the intercritically treated steels with deformed preliminary microstructures. Ultra-fine ferrite with lath and polygonal morphologies, lath-like martensite, blocky-like martensite, higher GNDs density, and more fraction of <span><math><mo>∑</mo><mn>3</mn></math></span> CSLBs were detected in this steel. Such a complex microstructure attained extraordinary strength-elongation-toughness synergy. Yield strength, ultimate tensile strength, elongation, tensile toughness, and Charpy impact energy equaled 1175±19 MPa, 1402±25 MPa, 11.7±0.4 %, 150.8±13.0 MJ/m<sup>3</sup>, and 102±2 J, respectively. Dimple and cleavage features were observed in the fracture surfaces of all intercritically treated steels after performing uniaxial tensile and Charpy impact tests at the room temperature. Failure and toughening mechanisms were comprehensively discussed, as well.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114556"},"PeriodicalIF":4.8,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723140","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 : 2024-11-16DOI: 10.1016/j.matchar.2024.114561
Chuan-jiang Wu , Liang Zhang , Si-yong Gu , Nan Jiang , Hyoung Seop Kim , Yu-hao Chen
The wetting behavior of Sn-1.0Ag-0.5Cu-xTi (SAC-xTi, where x = 2, 4, 6) powder on the AlN surface was investigated. The SAC-xTi powder developed a high-quality tin-based metallization layer on the AlN surface when heated at 900 °C for 30 min. The pre-metallized AlN was successfully soldered to the Cu substrate using SAC solder paste at 250 °C. The wetting angle gradually increased with rising Ti content in SAC, achieving a minimum wetting angle of 8.2° with SAC-2Ti powder on the AlN surface. Additionally, there was observed a homogeneous and sequential flat pre-metallized layer on the surface of AlN. However, the layer becomes discontinuous as the Ti content increases, leading to the appearance of significant surface irregularities (bumps). Low-temperature preparation of Cu/SAC/pre-metallized AlN joints with the typical microstructures of: Cu/Cu3Sn layer/Cu6Sn5 layer/β-Sn layer (containing Ag3Sn and Cu6Sn5)/TiN layer/AlN. The pre-metallized layer significantly influenced the shear strength of the joints, which decreased with increasing Ti content. The shear strength of joints with pre-metallized layers formed using SAC-2Ti peaked at 24.27 MPa. As Ti content increased, the fracture paths gradually approached the AlN surface from the solder matrix.
{"title":"Shear properties of low-temperature soldered joints of aluminum nitride metallized with Sn-1.0Ag-0.5Cu-Ti alloys","authors":"Chuan-jiang Wu , Liang Zhang , Si-yong Gu , Nan Jiang , Hyoung Seop Kim , Yu-hao Chen","doi":"10.1016/j.matchar.2024.114561","DOIUrl":"10.1016/j.matchar.2024.114561","url":null,"abstract":"<div><div>The wetting behavior of Sn-1.0Ag-0.5Cu-<em>x</em>Ti (SAC-<em>x</em>Ti, where <em>x</em> = 2, 4, 6) powder on the AlN surface was investigated. The SAC-xTi powder developed a high-quality tin-based metallization layer on the AlN surface when heated at 900 °C for 30 min. The pre-metallized AlN was successfully soldered to the Cu substrate using SAC solder paste at 250 °C. The wetting angle gradually increased with rising Ti content in SAC, achieving a minimum wetting angle of 8.2° with SAC-2Ti powder on the AlN surface. Additionally, there was observed a homogeneous and sequential flat pre-metallized layer on the surface of AlN. However, the layer becomes discontinuous as the Ti content increases, leading to the appearance of significant surface irregularities (bumps). Low-temperature preparation of Cu/SAC/pre-metallized AlN joints with the typical microstructures of: Cu/Cu<sub>3</sub>Sn layer/Cu<sub>6</sub>Sn<sub>5</sub> layer/β-Sn layer (containing Ag<sub>3</sub>Sn and Cu<sub>6</sub>Sn<sub>5</sub>)/TiN layer/AlN. The pre-metallized layer significantly influenced the shear strength of the joints, which decreased with increasing Ti content. The shear strength of joints with pre-metallized layers formed using SAC-2Ti peaked at 24.27 MPa. As Ti content increased, the fracture paths gradually approached the AlN surface from the solder matrix.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114561"},"PeriodicalIF":4.8,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723692","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 : 2024-11-15DOI: 10.1016/j.matchar.2024.114554
Weifeng Xu, Chao Wang, Hongjian Lu, He Suo, Yanfei Wang, Huan Wang
The stress corrosion behavior of 7085-T7452 high-strength aluminum alloy base material (BM) and its friction stir welding (FSW) joints under varying strain rates during slow strain rate tensile (SSRT) was investigated. The results show that the stress corrosion sensitivity (ISSRT) of both the BM and FSW joints decreases with the increase of strain rate from 10−7 s−1 to 10−5 s−1. Moreover, the BM demonstrates lower ISSRT than the joints. The cracks in the joints exhibit dendritic paths along grain boundaries, with evidence of crack arrest marking (CAM) at localized areas in 3.5 wt% NaCl solution, suggesting both anodic dissolution and hydrogen-induced cracking simultaneously govern the propagation of stress corrosion cracks. There is the forced more test time in the slower strain rate, and the accumulation of stress corrosion coupling damage accelerates with the time, eventually leading to the greater degradation in the stress corrosion resistance and the higher ISSRT.
{"title":"Effect of strain rates on stress corrosion sensitivity of 7085-T7452 thick-plate friction stir welding joint","authors":"Weifeng Xu, Chao Wang, Hongjian Lu, He Suo, Yanfei Wang, Huan Wang","doi":"10.1016/j.matchar.2024.114554","DOIUrl":"10.1016/j.matchar.2024.114554","url":null,"abstract":"<div><div>The stress corrosion behavior of 7085-T7452 high-strength aluminum alloy base material (BM) and its friction stir welding (FSW) joints under varying strain rates during slow strain rate tensile (SSRT) was investigated. The results show that the stress corrosion sensitivity (I<sub>SSRT</sub>) of both the BM and FSW joints decreases with the increase of strain rate from 10<sup>−7</sup> s<sup>−1</sup> to 10<sup>−5</sup> s<sup>−1</sup>. Moreover, the BM demonstrates lower I<sub>SSRT</sub> than the joints. The cracks in the joints exhibit dendritic paths along grain boundaries, with evidence of crack arrest marking (CAM) at localized areas in 3.5 wt% NaCl solution, suggesting both anodic dissolution and hydrogen-induced cracking simultaneously govern the propagation of stress corrosion cracks. There is the forced more test time in the slower strain rate, and the accumulation of stress corrosion coupling damage accelerates with the time, eventually leading to the greater degradation in the stress corrosion resistance and the higher I<sub>SSRT</sub>.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"218 ","pages":"Article 114554"},"PeriodicalIF":4.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723132","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}
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