Pub Date : 2025-02-01DOI: 10.1016/j.matchar.2024.114683
Bingyuan Han , Ruihua Zhang , Jun Yang , Yuxiang Liu , Yonglin Zhao , Xianghan Gao , Han Li
In this paper, the wetting and interfacial behavior of Al-Si-Cu-Zn-Ni-xY (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 wt%) brazing filler alloys on 7072 aluminum alloy substrate are investigated. Results show that the trace element Y can effectively improve the stability of the characteristic transition temperature of brazing filler alloys and reduce the melting interval at the same time. Accroding to the results of molecular dynamics simulations and arc wetting tests, the surface wetting process of the filler alloy is of five stages, i.e., preheating film-breaking stage, initial stage, rapid diffusion stage, limited diffusion stage and stabilization stage. When the content of Y in the Al-Si-Cu-Zn-Ni-Y brazing alloy increased from 0 wt% to 0.8 wt%, the wetting diffusion area of the brazing alloy increased from 261.298 mm2 to 305.658 mm2, and the wetting angle decreased from 18.28°to 12.857°。The microstructure shows that element Y can purify the wetted interface because Y reacts easily with Al2(Cu,Ni) in the brazing alloy to form Al4.4(Cu,Ni)6.6Y phase. The latter phase distributes discretely along the wetting interface and thus, the fluidity of the brazing alloy is improved.
{"title":"Effect of Y contents on surface wetting and interfacial behavior of Al-Si-Cu-Zn-Ni-xY brazing filler alloys on 7072 aluminum alloy","authors":"Bingyuan Han , Ruihua Zhang , Jun Yang , Yuxiang Liu , Yonglin Zhao , Xianghan Gao , Han Li","doi":"10.1016/j.matchar.2024.114683","DOIUrl":"10.1016/j.matchar.2024.114683","url":null,"abstract":"<div><div>In this paper, the wetting and interfacial behavior of Al-Si-Cu-Zn-Ni-<em>x</em>Y (<em>x</em> = 0, 0.2, 0.4, 0.6, 0.8, 1.0 wt%) brazing filler alloys on 7072 aluminum alloy substrate are investigated. Results show that the trace element Y can effectively improve the stability of the characteristic transition temperature of brazing filler alloys and reduce the melting interval at the same time. Accroding to the results of molecular dynamics simulations and arc wetting tests, the surface wetting process of the filler alloy is of five stages, i.e., preheating film-breaking stage, initial stage, rapid diffusion stage, limited diffusion stage and stabilization stage. When the content of Y in the Al-Si-Cu-Zn-Ni-Y brazing alloy increased from 0 wt% to 0.8 wt%, the wetting diffusion area of the brazing alloy increased from 261.298 mm<sup>2</sup> to 305.658 mm<sup>2</sup>, and the wetting angle decreased from 18.28°to 12.857°。The microstructure shows that element Y can purify the wetted interface because Y reacts easily with Al<sub>2</sub>(Cu,Ni) in the brazing alloy to form Al<sub>4.4</sub>(Cu,Ni)<sub>6.6</sub>Y phase. The latter phase distributes discretely along the wetting interface and thus, the fluidity of the brazing alloy is improved.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114683"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131008","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 : 2025-02-01DOI: 10.1016/j.matchar.2024.114650
Mahdi Mahmoudiniya , Anne-Sophie Thorr , Roumen H. Petrov , Marcel J.M. Hermans , Leo A.I. Kestens
Wire arc additive manufacturing (WAAM) is a significant area of interest within the field of additive manufacturing (AM). In the present research, WAAM technology was employed to deposit a Ni-based alloy on a ductile cast iron substrate to fabricate a bimetallic structure of Ni-45 %Fe alloy and ductile cast iron. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron back scattered diffraction (EBSD) and X-ray diffraction (XRD) were used to study phase transformations, microstructure and crystallographic texture development in interfacial regions as well as deposited material. The mechanical properties were also studied using micro-hardness and profilometry-based indentation plastometry (PIP) measurements. The results showed that a wide variety of phases are generated within the heat-affected zone (HAZ) and partially melted zone (PMZ). These phases form complex microstructures with single and double shell morphology. The deposited alloy has a face-centred cubic (FCC) structure, with some carbides and graphite that are formed during the solidification of the first deposited layer. The compositional changes were also observed across the interface. The texture of the deposited alloy showed around 30° deviation from 〈100〉 II building direction due to the shape and overlap of the melt pools. The present results provide a better understanding of interface development mechanisms during WAAM of bimetallic structures. The peak of the hardness across the interface was observed in PMZ because of the formation of a martensitic matrix. The PIP measurements showed that the and the of deposited alloy are lower than the cast iron base metal.
{"title":"Wire arc additive manufacturing of NiFe alloy/ductile cast iron bimetallic structure; phase transformations, microstructure and crystallographic texture","authors":"Mahdi Mahmoudiniya , Anne-Sophie Thorr , Roumen H. Petrov , Marcel J.M. Hermans , Leo A.I. Kestens","doi":"10.1016/j.matchar.2024.114650","DOIUrl":"10.1016/j.matchar.2024.114650","url":null,"abstract":"<div><div>Wire arc additive manufacturing (WAAM) is a significant area of interest within the field of additive manufacturing (AM). In the present research, WAAM technology was employed to deposit a Ni-based alloy on a ductile cast iron substrate to fabricate a bimetallic structure of Ni-45 %Fe alloy and ductile cast iron. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron back scattered diffraction (EBSD) and X-ray diffraction (XRD) were used to study phase transformations, microstructure and crystallographic texture development in interfacial regions as well as deposited material. The mechanical properties were also studied using micro-hardness and profilometry-based indentation plastometry (PIP) measurements. The results showed that a wide variety of phases are generated within the heat-affected zone (HAZ) and partially melted zone (PMZ). These phases form complex microstructures with single and double shell morphology. The deposited alloy has a face-centred cubic (FCC) structure, with some carbides and graphite that are formed during the solidification of the first deposited layer. The compositional changes were also observed across the interface. The texture of the deposited alloy showed around 30° deviation from 〈100〉 II building direction due to the shape and overlap of the melt pools. The present results provide a better understanding of interface development mechanisms during WAAM of bimetallic structures. The peak of the hardness across the interface was observed in PMZ because of the formation of a martensitic matrix. The PIP measurements showed that the <span><math><msub><mi>σ</mi><mi>y</mi></msub></math></span> and the <span><math><mi>UTS</mi></math></span> of deposited alloy are lower than the cast iron base metal.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114650"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130688","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 : 2025-02-01DOI: 10.1016/j.matchar.2024.114708
Yulai Xu , Lijun Fan , Liuyang Li , Liqin Shen , Xiaofei Wu , Xingyu Wang , Zhilong Tan
Effect of cobalt on microstructures and mechanical properties of Nimonic 80A has been investigated. Room temperature tensile strength increases by about 8.8%, and stress-rupture life at 750 °C/310 MPa increases by about 53.0% of 5Co alloy. Area fraction of γ' linearly increases from about 59.6% to 65.6% and average diameter of γ' significantly decreases from about 21.0 to 6.6 nm with the increased Co content after full heat treatment. The γ' exhibits a coherent orientation relationship with γ on {100} and {110}. Area fraction of γ' decreases and average size of γ' increases after stress-rupture test for each alloy due to the coarsening of approximately spherical γ' particles, but addition of Co can stabilize γ' phase because the average size of γ' in 5Co alloy is smaller than that in 2Co alloy. The lattice misfit of γ'/γ increases with the increased Co content both before and after stress-rupture test, but the lattice misfit for each alloy slightly decreases after stress-rupture test compared with that after full heat treatment. The addition of Co can easily lead to the appearance of numerous dislocations, and significantly varied interplanar spacing of {111} and {200} in γ phase. The blocky Cr23C6 carbide prefers to precipitate at GBs with an orientation relationship with the nearby γ matrix on {100}, the Cr23C6 carbide can suppress the movement of dislocations and grain boundaries, which benefits better mechanical properties.
{"title":"Microstructure evolution and improved mechanical properties of a cobalt modified nickel-based superalloy","authors":"Yulai Xu , Lijun Fan , Liuyang Li , Liqin Shen , Xiaofei Wu , Xingyu Wang , Zhilong Tan","doi":"10.1016/j.matchar.2024.114708","DOIUrl":"10.1016/j.matchar.2024.114708","url":null,"abstract":"<div><div>Effect of cobalt on microstructures and mechanical properties of Nimonic 80A has been investigated. Room temperature tensile strength increases by about 8.8%, and stress-rupture life at 750 °C/310 MPa increases by about 53.0% of 5Co alloy. Area fraction of γ' linearly increases from about 59.6% to 65.6% and average diameter of γ' significantly decreases from about 21.0 to 6.6 nm with the increased Co content after full heat treatment. The γ' exhibits a coherent orientation relationship with γ on {100} and {110}. Area fraction of γ' decreases and average size of γ' increases after stress-rupture test for each alloy due to the coarsening of approximately spherical γ' particles, but addition of Co can stabilize γ' phase because the average size of γ' in 5Co alloy is smaller than that in 2Co alloy. The lattice misfit of γ'/γ increases with the increased Co content both before and after stress-rupture test, but the lattice misfit for each alloy slightly decreases after stress-rupture test compared with that after full heat treatment. The addition of Co can easily lead to the appearance of numerous dislocations, and significantly varied interplanar spacing of {111} and {200} in γ phase. The blocky Cr<sub>23</sub>C<sub>6</sub> carbide prefers to precipitate at GBs with an orientation relationship with the nearby γ matrix on {100}, the Cr<sub>23</sub>C<sub>6</sub> carbide can suppress the movement of dislocations and grain boundaries, which benefits better mechanical properties.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114708"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130905","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 : 2025-02-01DOI: 10.1016/j.matchar.2025.114714
Abdelkader Khalfallah , Sid Ahmed Amzert , Fahd Arbaoui , Nacereddine Titouche , Noureddine Selmi , Piotr Bazarnik , Hiba Azzeddine , Thierry Baudin , François Brisset , Yi Huang , Terence G. Langdon
The corrosion behavior of a commercial Al-6061 alloy was explored in a 3.5 % (wt%) NaCl solution after high-pressure torsion (HPT) processing at room temperature for numbers of revolutions of N = 0, 1/2, 2 and 10 turns. The microstructures revealed by electron backscatter diffraction (EBSD) showed excellent grain refinement from 121 ± 5 to 0.44 ± 0.1 μm after N = 10 turns with a high fraction of high-angle grain boundaries (∼65 %). The results from electrochemical tests demonstrate that HPT processing significantly improves the corrosion resistance and reduces the corrosion rate due to a combination of grain refinement, an increased dislocation density and texture weakening. The corrosion mechanism was not affected by the HPT processing and found to be controlled by charge transfer. The corrosion morphology of the HPT-processed sample taken through N = 10 turns and observed after 14 days of immersion showed a smooth surface except for the presence of some corrosion microcracks around large particles enriched with Zn and Fe elements.
{"title":"Corrosion performance of Al-6061 alloy after high-pressure torsion processing","authors":"Abdelkader Khalfallah , Sid Ahmed Amzert , Fahd Arbaoui , Nacereddine Titouche , Noureddine Selmi , Piotr Bazarnik , Hiba Azzeddine , Thierry Baudin , François Brisset , Yi Huang , Terence G. Langdon","doi":"10.1016/j.matchar.2025.114714","DOIUrl":"10.1016/j.matchar.2025.114714","url":null,"abstract":"<div><div>The corrosion behavior of a commercial Al-6061 alloy was explored in a 3.5 % (wt%) NaCl solution after high-pressure torsion (HPT) processing at room temperature for numbers of revolutions of <em>N</em> = 0, 1/2, 2 and 10 turns. The microstructures revealed by electron backscatter diffraction (EBSD) showed excellent grain refinement from 121 ± 5 to 0.44 ± 0.1 μm after <em>N</em> = 10 turns with a high fraction of high-angle grain boundaries (∼65 %). The results from electrochemical tests demonstrate that HPT processing significantly improves the corrosion resistance and reduces the corrosion rate due to a combination of grain refinement, an increased dislocation density and texture weakening. The corrosion mechanism was not affected by the HPT processing and found to be controlled by charge transfer. The corrosion morphology of the HPT-processed sample taken through <em>N</em> = 10 turns and observed after 14 days of immersion showed a smooth surface except for the presence of some corrosion microcracks around large particles enriched with Zn and Fe elements.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114714"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130908","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 : 2025-02-01DOI: 10.1016/j.matchar.2024.114669
Jin-Bum Kim, Junha Lee, In-Gyeong Kim, Yong-Bum Park, Se-Eun Shin
{"title":"Erratum to “The effect of thermomechanical treatment on the electrodeposited Invar alloy for FMM” [Matarials Characterization, Volume 210, (2024) 113809]","authors":"Jin-Bum Kim, Junha Lee, In-Gyeong Kim, Yong-Bum Park, Se-Eun Shin","doi":"10.1016/j.matchar.2024.114669","DOIUrl":"10.1016/j.matchar.2024.114669","url":null,"abstract":"","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114669"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130911","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}
The η-Ni6AlNb in GH4169D could pin grain boundaries, and hinder crack propagation. However, the dissolution of the η phase at 1020 °C causes the notch sensitivity in GH4169D. So low-melting-point alloys, Cu-30Ag-32Zn-1Sn (wt%) (CuAgZnSn), were employed to achieve high-strength brazing of GH4169D at different brazing temperatures (850, 870, 890, 910, and 930 °C) for 30 min and 890 °C for different holding time (10, 60, and 120 min). The influence of the brazing process on the interface microstructure, mechanical properties, and fracture behavior of GH4169D/CuAgZnSn/GH4169D joints was investigated. The brazed seam (BS) was mainly composed of (Cu, Zn)ss and (Ag, Zn)ss. The BS achieved isothermal solidification at 890 °C for 30 min and an ordered solid solution Cu2NiZn formed at 890 °C for 60 min. Meanwhile, the content of (Ag, Cu, Zn)ss decreased. However, as the holding time increased from 60 min to 120 min, the content of (Ag, Cu, Zn)ss increased from 0.7 % to 40.3 %. This was mainly because of the reduced solid solubility of Ag in the (Cu, Zn, Ni)ss as the Ni increased. The interface structure of the brazed joint at 890 °C for 60 min was GH4169D/Cu2NiZn + Cr-rich (Cr, Ni, Cu)ss/Cu2NiZn + Ag-rich (Ag, Cu, Zn)ss + Cu-rich (Cu, Zn, Ni, Cr)ss/Cu2NiZn + Cr-rich (Cr, Ni, Cu)ss/GH4169D. The shear strength of the joints reached 708 MPa. As the holding times increased, the crack initiated from the BS/substrates interface with drastic changes in hardness to the BS. The fracture morphology changed from typical brittle cleavage fracture characteristics to dimples and cleavage steps.
{"title":"High-strength GH4169D joint brazed with medium temperature Cu-30Ag-32Zn-1Sn filler metal","authors":"Xin Jiang, Honggang Dong, Liangliang Zhang, Zhiwei Qin, Yinchen Wang, Bomin Zhao, Peng Li","doi":"10.1016/j.matchar.2024.114662","DOIUrl":"10.1016/j.matchar.2024.114662","url":null,"abstract":"<div><div>The η-Ni<sub>6</sub>AlNb in GH4169D could pin grain boundaries, and hinder crack propagation. However, the dissolution of the η phase at 1020 °C causes the notch sensitivity in GH4169D. So low-melting-point alloys, Cu-30Ag-32Zn-1Sn (wt%) (CuAgZnSn), were employed to achieve high-strength brazing of GH4169D at different brazing temperatures (850, 870, 890, 910, and 930 °C) for 30 min and 890 °C for different holding time (10, 60, and 120 min). The influence of the brazing process on the interface microstructure, mechanical properties, and fracture behavior of GH4169D/CuAgZnSn/GH4169D joints was investigated. The brazed seam (BS) was mainly composed of (Cu, Zn)<sub>ss</sub> and (Ag, Zn)<sub>ss</sub>. The BS achieved isothermal solidification at 890 °C for 30 min and an ordered solid solution Cu<sub>2</sub>NiZn formed at 890 °C for 60 min. Meanwhile, the content of (Ag, Cu, Zn)<sub>ss</sub> decreased. However, as the holding time increased from 60 min to 120 min, the content of (Ag, Cu, Zn)<sub>ss</sub> increased from 0.7 % to 40.3 %. This was mainly because of the reduced solid solubility of Ag in the (Cu, Zn, Ni)<sub>ss</sub> as the Ni increased. The interface structure of the brazed joint at 890 °C for 60 min was GH4169D/Cu<sub>2</sub>NiZn + Cr-rich (Cr, Ni, Cu)<sub>ss</sub>/Cu<sub>2</sub>NiZn + Ag-rich (Ag, Cu, Zn)<sub>ss</sub> + Cu-rich (Cu, Zn, Ni, Cr)<sub>ss</sub>/Cu<sub>2</sub>NiZn + Cr-rich (Cr, Ni, Cu)<sub>ss</sub>/GH4169D. The shear strength of the joints reached 708 MPa. As the holding times increased, the crack initiated from the BS/substrates interface with drastic changes in hardness to the BS. The fracture morphology changed from typical brittle cleavage fracture characteristics to dimples and cleavage steps.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114662"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131005","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 : 2025-02-01DOI: 10.1016/j.matchar.2024.114642
Erika Zaiser , Andrea Fantin , Anna M. Manzoni , René Hesse , Daniel M. Többens , Wei-Che Hsu , Hideyuki Murakami , An-Chou Yeh , Michael J. Pavel , Mark L. Weaver , Huihui Zhu , Yuan Wu , Florian Vogel
In this study, we examine a high entropy superalloy (HESA-Y1: Ni49.37Co20Cr7Fe4Al11.6Ti6Re1Mo0.5W0.5Hf0.03 at%), focusing on hierarchical microstructure formation and its effects on mechanical properties. Thermodynamic modeling using Thermo-Calc predicts equilibrium phase fractions, compositions, and transition temperatures, which are validated by experimental data from differential scanning calorimetry (DSC). Transmission electron microscopy (TEM) reveals that secondary aging induces nanometer-sized γ particles within γ' precipitates, forming a hierarchical γ/γ' microstructure. Atom probe tomography (APT) confirms supersaturation of γ' precipitates with γ-forming elements (Co, Cr, Fe), driving γ particle formation, and measures interfacial widths between γ' and γ phases. Partitioning coefficients derived from APT align with Thermo-Calc predictions for most elements. Vickers microhardness testing shows an increase of about 50 HV in the hierarchical microstructure compared to the conventional one. In situ synchrotron X-ray diffraction (XRD) from 25 to 750 °C determines a small, negative lattice misfit δ between γ and γ' phases, suggesting enhanced microstructural stability, consistent with Thermo-Calc calculations. Our methodological approach enables measurement of the unconstrained lattice parameter of phase-extracted γ' in a single-crystal XRD setup. Due to their small size and low volume fraction, γ particles do not produce distinct reflections in the X-ray diffractogram. Elucidating hierarchical microstructures across multiple scales, we establish that the presence of Re and Hf and controlled aging processes lead to enhanced mechanical properties, offering valuable insights for the design of advanced high entropy superalloys.
{"title":"Elucidating hierarchical microstructures in high entropy superalloys: An integrated multiscale study","authors":"Erika Zaiser , Andrea Fantin , Anna M. Manzoni , René Hesse , Daniel M. Többens , Wei-Che Hsu , Hideyuki Murakami , An-Chou Yeh , Michael J. Pavel , Mark L. Weaver , Huihui Zhu , Yuan Wu , Florian Vogel","doi":"10.1016/j.matchar.2024.114642","DOIUrl":"10.1016/j.matchar.2024.114642","url":null,"abstract":"<div><div>In this study, we examine a high entropy superalloy (HESA-Y1: Ni<sub>49.37</sub>Co<sub>20</sub>Cr<sub>7</sub>Fe<sub>4</sub>Al<sub>11.6</sub>Ti<sub>6</sub>Re<sub>1</sub>Mo<sub>0.5</sub>W<sub>0.5</sub>Hf<sub>0.03</sub> at%), focusing on hierarchical microstructure formation and its effects on mechanical properties. Thermodynamic modeling using Thermo-Calc predicts equilibrium phase fractions, compositions, and transition temperatures, which are validated by experimental data from differential scanning calorimetry (DSC). Transmission electron microscopy (TEM) reveals that secondary aging induces nanometer-sized γ particles within γ' precipitates, forming a hierarchical γ/γ' microstructure. Atom probe tomography (APT) confirms supersaturation of γ' precipitates with γ-forming elements (Co, Cr, Fe), driving γ particle formation, and measures interfacial widths between γ' and γ phases. Partitioning coefficients derived from APT align with Thermo-Calc predictions for most elements. Vickers microhardness testing shows an increase of about 50 HV in the hierarchical microstructure compared to the conventional one. <em>In situ</em> synchrotron X-ray diffraction (XRD) from 25 to 750 °C determines a small, negative lattice misfit δ between γ and γ' phases, suggesting enhanced microstructural stability, consistent with Thermo-Calc calculations. Our methodological approach enables measurement of the unconstrained lattice parameter of phase-extracted γ' in a single-crystal XRD setup. Due to their small size and low volume fraction, γ particles do not produce distinct reflections in the X-ray diffractogram. Elucidating hierarchical microstructures across multiple scales, we establish that the presence of Re and Hf and controlled aging processes lead to enhanced mechanical properties, offering valuable insights for the design of advanced high entropy superalloys.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114642"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130799","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 : 2025-02-01DOI: 10.1016/j.matchar.2025.114807
Zhaotian Wang , Yongquan Ning , Qingqi Meng , Bingchao Xie , Shuo Huang , Wenyun Zhang , Beijiang Zhang
Since the concentration of refractory elements, such as W and Mo, increases in superalloys, the brittle μ phases, specifically (Co, Cr)7(W, Mo)6, tend to precipitate readily. These μ phases frequently serve as crack initiation sites, leading to a significant reduction in the lifetime of alloys. The present study focuses on the effect of μ phases on room-temperature tensile plasticity of a Ni-Co-Cr-based superalloy containing 4.0 wt% W and 4.0 wt% Mo during long-term aging. The objective is to analyze the precipitation behavior of μ phases and their influence on the elongation. With the precipitation of μ phases, W and Mo diffuse from the γ matrix into the μ phase, and meanwhile, the size and area fraction of μ phases initially increase before stabilizing. Notably, at an aging temperature of 800 °C, Mo exhibits a stronger diffusion ability compared to W. The depletion of solute atoms in the γ matrix, results the weakening of solid solution strength. Therefore, during tensile tests, more intergranular cracks propagate along the γ matrix interface near μ phases and γ' precipitates. Regarding the fracture characteristics, as the size and area fraction of μ phase increase, a greater number of dislocations pile-up near grain boundaries, leading to the formation of numerous creaks through shearing and bypassing. Moreover, the elongation significantly decreases from 17 to 19 % to 8–12 % after aging for more than 1000 h. This work enhances our understanding of μ precipitation and its effect on the material's plasticity.
{"title":"Effect of 800 °C/10,000 h aging-induced μ phase on plasticity in Ni-Co-Cr based superalloys","authors":"Zhaotian Wang , Yongquan Ning , Qingqi Meng , Bingchao Xie , Shuo Huang , Wenyun Zhang , Beijiang Zhang","doi":"10.1016/j.matchar.2025.114807","DOIUrl":"10.1016/j.matchar.2025.114807","url":null,"abstract":"<div><div>Since the concentration of refractory elements, such as W and Mo, increases in superalloys, the brittle μ phases, specifically (Co, Cr)<sub>7</sub>(W, Mo)<sub>6</sub>, tend to precipitate readily. These μ phases frequently serve as crack initiation sites, leading to a significant reduction in the lifetime of alloys. The present study focuses on the effect of μ phases on room-temperature tensile plasticity of a Ni-Co-Cr-based superalloy containing 4.0 wt% W and 4.0 wt% Mo during long-term aging. The objective is to analyze the precipitation behavior of μ phases and their influence on the elongation. With the precipitation of μ phases, W and Mo diffuse from the γ matrix into the μ phase, and meanwhile, the size and area fraction of μ phases initially increase before stabilizing. Notably, at an aging temperature of 800 °C, Mo exhibits a stronger diffusion ability compared to W. The depletion of solute atoms in the γ matrix, results the weakening of solid solution strength. Therefore, during tensile tests, more intergranular cracks propagate along the γ matrix interface near μ phases and γ' precipitates. Regarding the fracture characteristics, as the size and area fraction of μ phase increase, a greater number of dislocations pile-up near grain boundaries, leading to the formation of numerous creaks through shearing and bypassing. Moreover, the elongation significantly decreases from 17 to 19 % to 8–12 % after aging for more than 1000 h. This work enhances our understanding of μ precipitation and its effect on the material's plasticity.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114807"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143306202","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 : 2025-02-01DOI: 10.1016/j.matchar.2024.114694
Congqing Liu , Jingjing Liao , Jun Wu , Fuen Zhang , Hongling Zhou , An Yan , Yuzhen Jia , Haiming Zhang , Quan Li , Xun Dai , Chao Sun , Baifeng Luan
Molybdenum alloys are promising materials for high-temperature gas-cooled reactor fuel cladding due to their excellent performance at elevated temperatures, favorable mechanical properties, corrosion resistance, and low neutron absorption cross-section. However, their high melting point and inherent hardness require annealing to improve processability. This study investigates the effects of vacuum annealing on the microstructure and texture evolution of rotary swaged MoRe alloys. The as-swaged alloy exhibits a fibrous structure with elongated grains along the axial direction (AD). Annealing at 1200 °C results in a bimodal microstructure, with both deformed and recrystallized grains, indicating a partially recrystallized (PRX) state. Furthermore, annealing at 1300 °C leads to a completely recrystallized (CRX) microstructure. The recrystallization mechanism is primarily driven by subgrains coalescence. The texture of the rotary swaged MoRe alloy is dominated by a strong 〈101〉//AD fiber texture, accompanied by a weaker 〈001〉//AD texture. After recrystallization, the intensity of the <101>//AD texture decreases, while the <001>//AD texture becomes more prominent. These texture changes suggest that the <001>//AD texture promotes recrystallization, whereas the <101>//AD texture hinders it. The evolution of the recrystallization texture is attributed to the preferential growth of <001>//AD grains and stress-driven grain rotation. These findings provide valuable insights for optimizing the heat treatment process of rotary swaged MoRe alloys.
{"title":"The insight effect of texture components on the recrystallization behavior of MoRe alloy","authors":"Congqing Liu , Jingjing Liao , Jun Wu , Fuen Zhang , Hongling Zhou , An Yan , Yuzhen Jia , Haiming Zhang , Quan Li , Xun Dai , Chao Sun , Baifeng Luan","doi":"10.1016/j.matchar.2024.114694","DOIUrl":"10.1016/j.matchar.2024.114694","url":null,"abstract":"<div><div>Molybdenum alloys are promising materials for high-temperature gas-cooled reactor fuel cladding due to their excellent performance at elevated temperatures, favorable mechanical properties, corrosion resistance, and low neutron absorption cross-section. However, their high melting point and inherent hardness require annealing to improve processability. This study investigates the effects of vacuum annealing on the microstructure and texture evolution of rotary swaged Mo<img>Re alloys. The as-swaged alloy exhibits a fibrous structure with elongated grains along the axial direction (AD). Annealing at 1200 °C results in a bimodal microstructure, with both deformed and recrystallized grains, indicating a partially recrystallized (PRX) state. Furthermore, annealing at 1300 °C leads to a completely recrystallized (CRX) microstructure. The recrystallization mechanism is primarily driven by subgrains coalescence. The texture of the rotary swaged Mo<img>Re alloy is dominated by a strong 〈101〉//AD fiber texture, accompanied by a weaker 〈001〉//AD texture. After recrystallization, the intensity of the <101>//AD texture decreases, while the <001>//AD texture becomes more prominent. These texture changes suggest that the <001>//AD texture promotes recrystallization, whereas the <101>//AD texture hinders it. The evolution of the recrystallization texture is attributed to the preferential growth of <001>//AD grains and stress-driven grain rotation. These findings provide valuable insights for optimizing the heat treatment process of rotary swaged Mo<img>Re alloys.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114694"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130904","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}
In ceramic particle reinforced iron matrix composites, a significant increase in the volume fraction of the reinforcing phase results in enhanced strength but a dramatic decrease in toughness. This study prepared TaCp/Fe cluster-reinforced iron matrix composites through a combination of lost foam casting and in-situ reaction. During lost foam casting, tantalum wires react with gray cast iron in a solid-liquid process to form a preform. In the subsequent in-situ solid-solid reaction, carbon atoms continuously fill the lattice gaps of Ta to form TaC, which then results in the formation of a three-dimensional cluster-reinforced structure of TaCp and α-Fe around the tantalum wires. TaCp/Fe cluster-reinforced iron matrix composites have a spatial architecture combining soft and hard phases: The tantalum wires, ferrite, and the carbon-poor regions surrounding the reinforcement constitute the soft regions; TaCp and its cluster reinforcement exhibits excellent load-bearing properties. The in-situ reaction samples obtained at 1115 °C for 7 h exhibited a compressive yield strength of 419 ± 9 MPa and a strain of 21.1 ± 0.6 %, which are 1.8 times and 1.3 times that of the matrix, respectively. In conclusion, the TaCp/Fe cluster-reinforced iron matrix composites prepared by lost foam casting combined with in-situ reaction method have favorable strength-toughness matching properties.
{"title":"Preparation and formation mechanism of TaCp/Fe cluster-reinforced iron matrix composites","authors":"Nana Zhao , Zehao Zhang , Liangliang Wang , Chengxuan Zhou , Hao Chen , Lisheng Zhong , Yunhua Xu","doi":"10.1016/j.matchar.2024.114693","DOIUrl":"10.1016/j.matchar.2024.114693","url":null,"abstract":"<div><div>In ceramic particle reinforced iron matrix composites, a significant increase in the volume fraction of the reinforcing phase results in enhanced strength but a dramatic decrease in toughness. This study prepared TaC<sub>p</sub>/Fe cluster-reinforced iron matrix composites through a combination of lost foam casting and in-situ reaction. During lost foam casting, tantalum wires react with gray cast iron in a solid-liquid process to form a preform. In the subsequent in-situ solid-solid reaction, carbon atoms continuously fill the lattice gaps of Ta to form TaC, which then results in the formation of a three-dimensional cluster-reinforced structure of TaC<sub>p</sub> and α-Fe around the tantalum wires. TaC<sub>p</sub>/Fe cluster-reinforced iron matrix composites have a spatial architecture combining soft and hard phases: The tantalum wires, ferrite, and the carbon-poor regions surrounding the reinforcement constitute the soft regions; TaC<sub>p</sub> and its cluster reinforcement exhibits excellent load-bearing properties. The in-situ reaction samples obtained at 1115 °C for 7 h exhibited a compressive yield strength of 419 ± 9 MPa and a strain of 21.1 ± 0.6 %, which are 1.8 times and 1.3 times that of the matrix, respectively. In conclusion, the TaC<sub>p</sub>/Fe cluster-reinforced iron matrix composites prepared by lost foam casting combined with in-situ reaction method have favorable strength-toughness matching properties.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"220 ","pages":"Article 114693"},"PeriodicalIF":4.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130907","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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