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Effect of hydrogenation on microstructure and mechanical properties of new zirconium alloy

INTERMETALLICS 2025年 178卷

作者： Wang, Ying Wang, Ruiping Wang, Zeming Xiao, Zonglin Niu, Shiyu Yang, Xu Yang, Zhenwen Tianjin Univ Sch Mat Sci & Engn Tianjin Key Lab Adv Joining Technol Tianjin 300350 Peoples R China Nucl Power Inst China Chengdu 610041 Peoples R China

The zirconium alloy was thermo-hydrogen processed with 0.02 wt% and 0.2 wt% hydrogen, and the impact of hydrogen content on the microstructure and mechanical properties of the alloy was investigated. The hydrides in the hydrogen-treated alloys were identified as S-ZrH1.66, which exhibit a semi-coherent boundary with the alpha-Zr matrix and an orientation relationship of (0001)alpha-Zr//(111)S. The hydride platelets tend to align in lines parallel to the rolling direction (RD) and transverse direction (TD) at a slow cooling rate after thermo-hydrogenation. Thermo-hydrogen processing introduced additional intragranular secondary phases characterized as largersized ZrFe2 compared to those present in the raw alloy. The tensile strength and elongation of the zirconium alloys decrease with increasing hydrogen content due to the elevated hardness and brittleness of the hydrides. Specifically, the tensile strength decreases from 476 MPa without hydrogen to 449 MPa with 200 ppm hydrogen and 433 MPa with 2000 ppm hydrogen. The elongation of specimens without hydrogen was 38.4 %, whereas specimens with 200 ppm and 2000 ppm hydrogen exhibited reductions of 6.3 % and 42.7 %, respectively. Specimens with 2000 ppm hydrogen exhibited significantly low elongation due to the increased quantity and size of hydride lines.

关键词： Zirconium alloy S -hydrides Mechanical properties microstructure development

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The effects of deposited layer thickness on the material and geometrical properties of L-DED processed AISI D2 tool steel

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CANADIAN METALLURGICAL QUARTERLY 2025年第2期64卷 383-395页

作者： Omar, S. M. T. Plucknett, K. P. Dalhousie Univ Dept Mech Engn Halifax NS B3H 4R2 Canada

This research focuses on the influences of the deposited layer thickness upon the material characteristics, dimensional accuracy, and also the surface roughness of AISI D2 tool steel processed by laser directed energy deposition (L-DED);while layer thickness was varied, the remaining L-DED system parameters were retained at fixed values. After laser deposition, the D2 specimens were assessed without applying any subsequent machining steps. Sample dimensional accuracy was assessed through both manual measurement and computational methods, with the latter using confocal laser scanning microscopy (CLSM). It was shown that increasing the layer thickness decreases the extent of sample overbuilding. The use of lower layer thicknesses reduced the top surface roughness. However, a monotonic effect was not observed for side surface roughness in relation to the deposited layer thickness. In addition, the microstructures of the L-DED samples were evaluated using a combination of scanning electron microscopy (SEM) with associated energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). It is shown that a dendritic morphology is formed for the L-DED processed samples, with a columnar grain structure. Furthermore, the primary crystalline phase generated with the dendritic structure was found to be austenite. The indentation hardness values for the L-DED fabricated parts were noted to be larger for thinner deposited layer thicknesses. Cette recherche se concentre sur les influences de l'& eacute;paisseur de la couche d & eacute;pos & eacute;e sur les caract & eacute;ristiques du mat & eacute;riau, la pr & eacute;cision dimensionnelle, ainsi que la rugosit & eacute;de surface de l'acier & agrave;outils AISI D2 trait & eacute;par d & eacute;p & ocirc;t d'& eacute;nergie dirig & eacute;par laser (L-DED);tandis qu'on variait l'& eacute;paisseur de la couche, on a conserv & eacute;& agrave;des valeurs fixes le reste des param & egrave;tres du syst & egrave;me L-DED. Apr

关键词： Dimensional accuracy Hardness Laser direct energy deposition Layer thickness microstructure development Surface roughness

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Analysis of the influence of the gas velocity, particle size and nucleation temperature on the thermal history and microstructure development in the tool steel during atomization

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JOURNAL OF ALLOYS AND COMPOUNDS 2014年第S1期615卷 S217-S223页

作者： Behulova, M. Mesarosova, J. Grgac, P. Slovak Univ Technol Bratislava Fac Mat Sci & Technol Trnava Trnava 91724 Slovakia

The paper deals with the analysis of the influence of the nitrogen gas velocity, particle size and nucleation temperature on the microstructure development in the tool steel of ledeburite type Ch12MF4 in the process of atomization. Three main types of solidification microstructures were identified using microscopic analysis in rapidly solidified powder particles: dendritic, cellular (grain-refined) and compound, representing the mixture of dendritic and cellular microstructures. It can be supposed that the transition from initially dendritic to compound and cellular or grain-refined microstructure occurs by the mechanism of thermally induced fragmentation of dendrites during quasi-isothermal period of solidification if additionally the recalescence temperature is sufficiently high. The microstructures documented the procedure of dendrites fragmentation and following spheroidization of dendrite fragments in rapidly solidified powder particles from the Ch12MF4 alloy are presented. Applying developed mathematical model of cooling and solidification of a single spherical droplet in atomization process, the influence of nitrogen gas velocity and other parameters as nucleation temperature on the thermal history of a droplet with various diameters during atomization is studied. Based on the comparison of results of mathematical modeling and microstructural observations, the thermophysical conditions for the transition from dendritic to cellular (grain-refined) microstructure development in the rapidly solidified powder particles from the Ch12MF4 steel are predicted. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Tool steel of ledeburite type Gas atomization Undercooling Rapid solidification Dendrite fragmentation microstructure development

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microstructure and mechanical behavior of TaxHf1-xC-SiC fabricated by reactive hot-pressing: Effect of Ta:Hf ratio

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JOURNAL OF THE AMERICAN CERAMIC SOCIETY 2024年第10期107卷 6974-6984页

作者： Ni, Dewei Qin, Yanyan Dong, Shaoming Univ Chinese Acad Sci Hangzhou Inst Adv Study Hangzhou Peoples R China Chinese Acad Sci Shanghai Inst Ceram State Key Lab High Performance Ceram & Superfine M Shanghai 200050 Peoples R China Chinese Acad Sci Shanghai Inst Ceram Struct Ceram & Composites Engn Res Ctr Shanghai Peoples R China

TaxHf1-xC are promising candidates for many applications under harsh environments due to their unique properties. Up until now, low-temperature densification is still a big challenge for these ceramics. Moreover, the effect of Ta:Hf ratio on microstructure development and mechanical behavior of the ceramics is not clear. In this work, highly dense TaxHf1-xC-SiC ceramics (x = 0.2, 0.4, 0.6, 0.8) were fabricated at 1700 degrees C by a novel reactive hot-pressing processing with 8 wt% Si as sintering aid, which present excellent mechanical properties. Fracture toughness of the ceramics is higher than 6.3 MPam(1/2), with the highest toughness achieved in Ta0.6Hf0.4C-SiC (8.5 MPam(1/2)). With the increase of Ta content, hardness of the ceramics tends to increase, while the bending strength tends to decrease. The highest bending strength is achieved in Ta0.2Hf0.8C-SiC (637 MPa), and the highest hardness is achieved in Ta0.8Hf0.2C-SiC (17.6 GPa). This work lays the foundation for the composition design of TaxHf1-xC-based ceramics and composites.

关键词： low-temperature densification mechanical properties microstructure development reactive hot-pressing TaxHf1-xC

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Influence of thermal history on the crystallization behavior of high-Bs Fe-based amorphous alloys

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Science China(Physics,Mechanics & Astronomy) 2023年第5期66卷 173-180页

作者： Bowen Zang Lijian Song Richard Parsons Jie Shen Meng Gao Yan Zhang Juntao Huo Yonghao Sun Fushan Li Kiyonori Suzuki Jun-Qiang Wang Weihua Wang CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application TechnologyNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Department of Materials Science and Engineering Monash UniversityClayton VIC 3800Australia Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

A crucial step in creating cutting-edge soft magnetic alloys is the nanocrystallization of Fe-based amorphous ***,it is unclear how the thermal history affects the *** this work,high-precision nanocalorimetry and in-situ hightemperature transmission electron microscopy are used to systematically examine how the pre-annealing relaxation process affects the nanocrystallization of Fe-based amorphous *** discover that the glass with more thermal energy storage will crystallize into superb nanocrystalline structures with exceptionally advanced soft *** soft magnetic properties of Fe-B nanocrystalline alloys can be improved by increasing the relaxation *** finding provides solid and clear evidence for the influences of thermal history on crystallization behavior for Fe-based amorphous alloys,which is helpful for designing advanced soft magnetic nanocrystalline alloys.

关键词： amorphous alloys enthalpy relaxation nanocrystallization microstructure development soft magnetic properties

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Imaging flow focusing and isolation of aqueous fluids in synthetic quartzite: implications for permeability and retained fluid fraction in deep-seated rocks

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PROGRESS IN EARTH AND PLANETARY SCIENCE 2024年第1期11卷 40页

作者： Fujita, Wakana Nakamura, Michihiko Uesugi, Kentaro Eichheimer, Philipp Thielmann, Marcel Golabek, Gregor J. Tohoku Univ Grad Sch Sci Dept Earth Sci Sendai 9808578 Japan Japan Synchrotron Radiat Res Inst Hyogo 6795198 Japan Univ Bayreuth Bayer Geoinst D-95440 Bayreuth Germany Math2Market D-67655 Kaiserslautern Germany Nucl Waste Management Org Japan Tokyo 1080014 Japan

The microstructure of realistic fluid-rock systems evolves to minimize the overall interfacial energy, enabling local variations in fluid geometry beyond ideal models. Consequently, the permeability-porosity relationship and fluid distribution in these systems may deviate from theoretical expectations. Here, we aimed to better understand the permeability development and fluid retention in deep-seated rocks at low fluid fractions by using a combined approach of high-resolution synchrotron radiation X-ray computed microtomography imaging of synthesized rocks and numerical permeability computation. We first synthesized quartzite using a piston-cylinder apparatus at different fluid fractions and wetting properties (wetting and non-wetting systems with dihedral angles of 52 degrees and 61 degrees-71 degrees, respectively) under conditions of efficient grain growth. Although all fluids should be connected along grain edges and tubules in the homogeneous isotropic wetting fluid-rock system enabling segregation by gravitational compaction in natural settings, the fluid connectivity rapidly decreased to similar to 0 when the total fluid fraction decreased to 0.030-0.037, as the non-ideality of quartzite, including the interfacial energy anisotropy (i.e., grain faceting), became critical. In non-wetting systems, where the minimum energy fluid fraction based solely on the dihedral angle is similar to 0.015-0.035, the isolated (disconnected) fractions was 0.048-0.062. A streamline computation in the non-wetting system revealed that with decreasing total porosity, flow focusing into fewer channels maintained permeability, allowing the effective segregation of the connected fluids. These results provide insight into how non-wetting fluids segregate from rocks and exemplify the fraction of retained fluids in non-wetting systems. Thus, the findings suggest a potential way for wetting system fluids to be transported into the deep Earth's interior, and the amount of fluids dragged do

关键词： Permeability Quartzite Digital rock physics Dihedral angle microstructure development

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Degradation Susceptibility of Al-2.18Mg-1.92Li Alloy in Severe Environmental Conditions

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MATERIALS 2025年第9期18卷 1938-1938页

作者： Kozina, Franjo Brodarac, Zdenka Zovko Petric, Mitja Batic, Barbara Setina Univ Zagreb Fac Met Sisak Croatia Univ Ljubljana Fac Nat Sci & Engn Ljubljana 1000 Slovenia Inst Met & Technol Ljubljana 1000 Slovenia

Due to the specific application of aluminum-magnesium-lithium (Al-Mg-Li) alloys in the transportation industry, it is necessary to consider the influence of microstructure development on material degradation under severe environmental conditions. This degradation was simulated according to the standard test method ASTM G34-01 (2018) on a newly designed and synthesized Al-2.1Mg-1.92Li alloy in the as-cast condition. The degradation susceptibility of the alloy was estimated by measuring the changes in the sample mass and microhardness, and the pH and chemical composition of the environment with respect to the exposure time. The influence of the microstructure constituents on the degradation of the alloy was determined using metallographic analysis of the exposed surface and cross-section of the samples after testing. During the degradation, dealloying of the alpha Al matrix through Li, Mg and Al component dissolution resulted in a decrease in the mass of the samples, an increase in the pH of the environment and changes in its chemical composition. This observation was also confirmed by the results of the metallographic analysis. The degradation involved the formation of cavities around the Al8Mg5 (beta) and Al2LiMg (T) intermetallic phases through an anodic dissolution mechanism. The increase in microhardness values after exposure indicated an increase in the stress around the degradation front due to the wedge effect of the degradation products. The results of the investigation support the potential application of the synthesized Al-2.1Mg-1.92Li alloy under the severe environmental conditions defined by the ASTM G34-01 (2018) standard.

关键词： aluminum-magnesium-lithium alloys microstructure development severe environmental conditions degradation dealloying

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On as-built microstructure and necessity of solution treatment in additively manufactured Inconel 939

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POWDER METALLURGY 2023年第1期66卷 3-11页

作者： Shaikh, Abdul Shaafi Rashidi, Masoud Minet-Lallemand, Kevin Hryha, Eduard Chalmers Univ Technol Dept Ind & Mat Sci Gothenburg Sweden Electro Opt Syst Finland Oy Lemminkaisenkatu 36 Turku 20520 Finland

Increased adoption of additively manufactured superalloys has led to the consideration of revised heat treatment approaches for these materials. The rapid cooling during additive manufacturing processes has been seen to suppress gamma prime (gamma ') precipitation, which has raised the possibilities for omitting the high-temperature solution treatment step that usually precedes ageing heat treatment for these alloys. In this work, the as-built microstructure of a high gamma prime fraction superalloy Inconel 939 is presented, where the absence of any gamma ' precipitation is notable. However, transmission electron microscopy shows the presence of nano-sized Eta (eta) phase. It is shown that the omission of solution treatment leads to the growth of the deleterious eta phase upon ageing, which results in embrittlement in tensile loading. It is concluded that at least for this particular alloy the solution treatment plays a critical role in the establishment of the required microstructure and hence cannot be omitted from the heat treatment.

关键词： Additive manufacturing laser powder bed fusion superalloy Inconel 939 heat treatment TEM microstructure development

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The influence of DED process parameters and heat-treatment cycle on the microstructure and hardness of AISI D2 tool steel

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JOURNAL OF MANUFACTURING PROCESSES 2022年 81卷 655-671页

作者： Omar, S. M. T. Plucknett, K. P. Dalhousie Univ Dept Mech Engn Halifax NS B3H 4R2 Canada

The impact of both the laser directed energy deposition (DED) process parameters and post-deposition heattreatment cycles on the microstructural characteristics and hardness are evaluated for cladding AISI D2 tool steel onto annealed AISI D2 substrates. The influences of powder feed rate, and laser scanning speed were assessed. After laser deposition, the DED samples were subjected to various tempering heat-treatment cycles. The microstructural and compositional characteristics of both the `as-printed' and heat-treated DED processed samples were investigated using scanning electron microscopy with energy dispersive X-ray spectroscopy, confocal laser scanning microscopy, and X-ray diffraction. The indentation and scratch hardness responses were assessed to evaluate the effects of various heat-treatment schedules, with comparison made to wrought D2. It was demonstrated that the microstructure of the DED processed samples had a dendritic morphology with columnar grains. Moreover, the hardness values of the DED fabricated parts were found to be higher than an annealed wrought D2, but lower than the quenched D2. Subsequent tempering of the DED printed parts resulted in a final hardness, essentially equivalent to the as-quenched level.

关键词： Tool steels Laser direct energy deposition Hardness microstructure development Tempering Heat-treatment

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ITZ properties of LWA surroundings in high strength mortar according to LWA/sand with relative humidity

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CONSTRUCTION AND BUILDING MATERIALS 2024年 451卷

作者： Pyeon, Sujeong Kim, Gyuyong Choi, Byungcheol Oh, Dayoung Leem, Yubin Kitagaki, Ryoma Nam, Jeongsoo Chungnam Natl Univ Dept Architectural Engn 99 Daehak ro Daejeon 34134 South Korea Hokkaido Univ Grad Sch Engn 5 Chome Kita 8 Jonishi Sapporo Hokkaido 0600808 Japan

The internal moisture content significantly influences the quality and durability of cement-based composite materials. However, reliable methods to analyze the moisture retention of concrete and mortar are lacking, particularly in relation to internal curing with lightweight aggregates (LWA). In this study, the internal moisture retention of mortar with different lightweight aggregate/sand (L/S) ratios was investigated while considering the absorption characteristics of LWA. Furthermore, the impact of internal moisture retention on the development of the interface transition zone (ITZ) between the LWA and cement matrix was analyzed. Additionally, compressive strength development was evaluated over different curing periods (3, 7, 28, 56, and 90 days) under internal curing conditions. The results showed that the L/S ratio, which is directly proportional to the amount of moisture absorbed, enhanced the compressive strength and plastic hardness, contributing to the development of depletion of internal moisture in the mortar was could be observed. The moisture consumption for different types of LWA was analyzed using CT scanning. XRD and SEM-EDS analyses confirmed the abundant presence of hydration products in the ITZ. This study demonstrates that the L/S ratio that considers the LWA absorption characteristics, can serve as a critical parameter for precisely correlating the curing time and compressive strength in internally cured mortars.

关键词： Lightweight aggregate Relative humidity LWA/sand Interface transition zone microstructure development

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