Pub Date : 2025-02-15DOI: 10.1016/j.matchar.2025.114853
Tianbi Zhang , Lukas Berners , Jakub Holzer , T. Ben Britton
Recent advances in scanning electron microscope (SEM) based Kikuchi diffraction have demonstrated the important potential for transmission and reflection methods, like transmission Kikuchi diffraction (TKD) and electron backscatter diffraction (EBSD). Furthermore, with the advent of compact direct electron detectors (DED) it has been possible to place the detector in a variety of configurations within the SEM chamber. This motivates the present work where we explore the similarities and differences of the different geometries that include on-axis TKD & off-axis TKD using electron transparent samples, as well as more conventional EBSD. Furthermore, we compare these with the newest method called “reflection Kikuchi diffraction” RKD where the sample is placed flat in the chamber and the detector is placed below the pole piece. Through remapping collected diffraction patterns, all these methods can be used to generate an experimental “diffraction sphere” that can be used to explore diffraction from any scattering vector from the unit cell, as well as the ability to perform band profile analysis. This diffraction sphere approach enables us to further probe specific differences between the methods, including for example thickness effects in TKD that can result in the generation of diffraction spots, as well as electron scattering path length effects that result in excess and deficiency variations, as well as inversion of bands in experimental patterns.
{"title":"Comparison of Kikuchi diffraction geometries in the scanning electron microscope","authors":"Tianbi Zhang , Lukas Berners , Jakub Holzer , T. Ben Britton","doi":"10.1016/j.matchar.2025.114853","DOIUrl":"10.1016/j.matchar.2025.114853","url":null,"abstract":"<div><div>Recent advances in scanning electron microscope (SEM) based Kikuchi diffraction have demonstrated the important potential for transmission and reflection methods, like transmission Kikuchi diffraction (TKD) and electron backscatter diffraction (EBSD). Furthermore, with the advent of compact direct electron detectors (DED) it has been possible to place the detector in a variety of configurations within the SEM chamber. This motivates the present work where we explore the similarities and differences of the different geometries that include on-axis TKD & off-axis TKD using electron transparent samples, as well as more conventional EBSD. Furthermore, we compare these with the newest method called “reflection Kikuchi diffraction” RKD where the sample is placed flat in the chamber and the detector is placed below the pole piece. Through remapping collected diffraction patterns, all these methods can be used to generate an experimental “diffraction sphere” that can be used to explore diffraction from any scattering vector from the unit cell, as well as the ability to perform band profile analysis. This diffraction sphere approach enables us to further probe specific differences between the methods, including for example thickness effects in TKD that can result in the generation of diffraction spots, as well as electron scattering path length effects that result in excess and deficiency variations, as well as inversion of bands in experimental patterns.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114853"},"PeriodicalIF":4.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-14DOI: 10.1016/j.matchar.2025.114851
Pengfei Gao , Jikang Fan , Baihao Cai , Jian Zhang , Dongqing Yang , Yong Peng , Kehong Wang
To establish process standards for arc-based directed energy deposition (DED-Arc) of the self-developed, low-cost Co-free maraging steel welding wire, the effect of different interlayer temperatures (50 °C and 350 °C) on the microstructure and mechanical properties of thin-walled components was studied. At an interlayer temperature of 50 °C, the average grain size of the specimens reached 14.06 μm, with high-angle grain boundaries (HAGBs) accounting for 49.5 %. The austenite content was 6.8 %, and the geometrically necessary dislocation (GND) density was 1.99 × 1014 m−2. When the interlayer temperature was increased to 350 °C, the average grain size increased significantly to 31.33 μm, accompanied by a decrease in the proportion of HAGBs to 45.5 %. Additionally, the austenite content rose to 11.8 %, while the GND density decreased to 1.71 × 1014 m−2. For specimens tested at an interlayer temperature of 50 °C, the tensile strength in the X-direction reached 1211.8 MPa with an elongation of 11.7 %, while in the Z-direction, it was 1186.6 MPa with an elongation of 8.7 %. However, increasing the interlayer temperature to 350 °C resulted in a decrease in tensile strength to 996.8 MPa and an increase in elongation to 23.4 % for X-direction specimens. Similarly, in the Z-direction, the tensile strength decreased to 969.1 MPa with an elongation of 22.2 %. Notably, increasing the interlayer temperature from 50 °C to 350 °C significantly enhanced impact toughness by adding up to 42.5 J/cm2 for X-direction specimens and by 32.4 J/cm2 for Z-direction specimens. The microhardness values of the deposited components were 352.4 HV and 300.3 HV at interlayer temperatures of 50 °C and 350 °C, respectively.
{"title":"Effect of interlayer temperature on the microstructure and mechanical properties of new Co-Free maraging steel fabricated by arc-based directed energy deposition","authors":"Pengfei Gao , Jikang Fan , Baihao Cai , Jian Zhang , Dongqing Yang , Yong Peng , Kehong Wang","doi":"10.1016/j.matchar.2025.114851","DOIUrl":"10.1016/j.matchar.2025.114851","url":null,"abstract":"<div><div>To establish process standards for arc-based directed energy deposition (DED-Arc) of the self-developed, low-cost Co-free maraging steel welding wire, the effect of different interlayer temperatures (50 °C and 350 °C) on the microstructure and mechanical properties of thin-walled components was studied. At an interlayer temperature of 50 °C, the average grain size of the specimens reached 14.06 μm, with high-angle grain boundaries (HAGBs) accounting for 49.5 %. The austenite content was 6.8 %, and the geometrically necessary dislocation (GND) density was 1.99 × 10<sup>14</sup> m<sup>−2</sup>. When the interlayer temperature was increased to 350 °C, the average grain size increased significantly to 31.33 μm, accompanied by a decrease in the proportion of HAGBs to 45.5 %. Additionally, the austenite content rose to 11.8 %, while the GND density decreased to 1.71 × 10<sup>14</sup> m<sup>−2</sup>. For specimens tested at an interlayer temperature of 50 °C, the tensile strength in the X-direction reached 1211.8 MPa with an elongation of 11.7 %, while in the <em>Z</em>-direction, it was 1186.6 MPa with an elongation of 8.7 %. However, increasing the interlayer temperature to 350 °C resulted in a decrease in tensile strength to 996.8 MPa and an increase in elongation to 23.4 % for X-direction specimens. Similarly, in the <em>Z</em>-direction, the tensile strength decreased to 969.1 MPa with an elongation of 22.2 %. Notably, increasing the interlayer temperature from 50 °C to 350 °C significantly enhanced impact toughness by adding up to 42.5 J/cm<sup>2</sup> for X-direction specimens and by 32.4 J/cm<sup>2</sup> for <em>Z</em>-direction specimens. The microhardness values of the deposited components were 352.4 HV and 300.3 HV at interlayer temperatures of 50 °C and 350 °C, respectively.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114851"},"PeriodicalIF":4.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436700","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 : 2025-02-14DOI: 10.1016/j.matchar.2025.114852
Y. Shi , S.N. Lan , J.Q. Yao , H.J. Huang , K. Wang , S.R. Li , X.W. Liu , Z.T. Fan
The strength-ductility trade-off of alloys has always been one of the key issues hindering the development of the metal industry. Herein, we found that the minor addition of Nb could strength FCC/BCC and BCC/B2 phase boundaries of multi-principal elements alloy (MPEA) and promoted the content of BCC phases. The ultimate tensile strength over 920 MPa with uniform elongation of 34.1 % at 873 K is accomplished in Fe31.75Ni27.75Cr25Al10Ti5Nb0.5 MPEA, which increased by 101.8 % in uniform elongation and 23.0 % in ultimate tensile strength in comparison to the Fe32Ni28Cr25Al10Ti5 MPEA. These findings provide a microalloying strategy to upgrade high-temperature mechanical properties within a strength and ductility window perhaps more effectively than existing strengthening and toughening approaches.
{"title":"Effective strengthening and toughening in multi-principal elements alloy via Nb addition at elevated temperature","authors":"Y. Shi , S.N. Lan , J.Q. Yao , H.J. Huang , K. Wang , S.R. Li , X.W. Liu , Z.T. Fan","doi":"10.1016/j.matchar.2025.114852","DOIUrl":"10.1016/j.matchar.2025.114852","url":null,"abstract":"<div><div>The strength-ductility trade-off of alloys has always been one of the key issues hindering the development of the metal industry. Herein, we found that the minor addition of Nb could strength FCC/BCC and BCC/B2 phase boundaries of multi-principal elements alloy (MPEA) and promoted the content of BCC phases. The ultimate tensile strength over 920 MPa with uniform elongation of 34.1 % at 873 K is accomplished in Fe<sub>31.75</sub>Ni<sub>27.75</sub>Cr<sub>25</sub>Al<sub>10</sub>Ti<sub>5</sub>Nb<sub>0.5</sub> MPEA, which increased by 101.8 % in uniform elongation and 23.0 % in ultimate tensile strength in comparison to the Fe<sub>32</sub>Ni<sub>28</sub>Cr<sub>25</sub>Al<sub>10</sub>Ti<sub>5</sub> MPEA. These findings provide a microalloying strategy to upgrade high-temperature mechanical properties within a strength and ductility window perhaps more effectively than existing strengthening and toughening approaches.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114852"},"PeriodicalIF":4.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474579","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 : 2025-02-14DOI: 10.1016/j.matchar.2025.114850
A. Szewczyk , A. Wójcik , W. Maziarz , N. Schell , R. Chulist
Three different martensitic crystal structures i.e. 10M, 14M, and NM of NiMnGa-based alloys, occurring in different forms, such as powders, polycrystalline melt-spun ribbons, and bulk single crystals were characterized in detail. The crystal structure of materials having the same chemical compositions and martensitic structures but existing in different forms were evaluated using high-energy synchrotron radiation, showing significant changes in lattice parameters. Additionally, the samples examined by high-resolution TEM imaging and electron diffraction showed local structure changes including variations of stacking fault sequence, and lattice distortion at the grain and twin boundaries. The changes in lattice parameters of unit cells as well as the intensity of modulation reflections have been discussed in terms of microstructure (single variant, multivariant state), internal stresses, dislocation density, atomic shuffling, periodic and partially periodic atom displacements. Moreover, the effect of heat treatment on microstrain level, dislocation density, and formation of martensitic structures was investigated.
{"title":"Structural differences between single crystalline and polycrystalline NiMnGa-based alloys","authors":"A. Szewczyk , A. Wójcik , W. Maziarz , N. Schell , R. Chulist","doi":"10.1016/j.matchar.2025.114850","DOIUrl":"10.1016/j.matchar.2025.114850","url":null,"abstract":"<div><div>Three different martensitic crystal structures i.e. 10M, 14M, and NM of NiMnGa-based alloys, occurring in different forms, such as powders, polycrystalline melt-spun ribbons, and bulk single crystals were characterized in detail. The crystal structure of materials having the same chemical compositions and martensitic structures but existing in different forms were evaluated using high-energy synchrotron radiation, showing significant changes in lattice parameters. Additionally, the samples examined by high-resolution TEM imaging and electron diffraction showed local structure changes including variations of stacking fault sequence, and lattice distortion at the grain and twin boundaries. The changes in lattice parameters of unit cells as well as the intensity of modulation reflections have been discussed in terms of microstructure (single variant, multivariant state), internal stresses, dislocation density, atomic shuffling, periodic and partially periodic atom displacements. Moreover, the effect of heat treatment on microstrain level, dislocation density, and formation of martensitic structures was investigated.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114850"},"PeriodicalIF":4.8,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.matchar.2025.114839
M. Belfi , M. Mariani , P. Martin , M. Santofimia , A. Gruttadauria , F. Deirmina , N. Lecis , S. Barella
This study investigates the microstructural development of commercial low-alloyed AISI 4340 steel through the synergistic application of Binder Jetting and Quenching and Partitioning (QP) processes. The material in the as-sintered condition exhibited significant variations in microstructure and mechanical properties, primarily influenced by the processing route. Carbon content was influenced by the building technique as decarburization was observed at different intensities mainly during the heating stage of sintering, driven by carbothermic reduction. Vacuum-debinding was found to be optimal, leading to the most homogeneous microstructure, predominantly granular bainite with superior hardness and tensile strength. Different QP treatments were optimized considering the decarburization effect on the optimal as-sintered condition, stabilizing 4–8 % retained austenite in a martensitic matrix, with optimal results observed after isothermal holding at either 220 °C or 240 °C for 30 min. These conditions resulted in high UTS values of 1231 MPa and 1151 MPa, respectively, compared to 750 MPa in the as-sintered state. Despite high tensile properties, A% was limited by the presence of residual porosity. This study highlights the critical importance of controlled debinding and sintering atmospheres as well as decarburization-informed QP treatments in achieving desirable microstructural and mechanical properties in additively manufactured AISI 4340 steel components.
{"title":"Microstructural development via synergic application of Binder jJetting and Quenching and Partitioning (QP) on commercial AISI 4340","authors":"M. Belfi , M. Mariani , P. Martin , M. Santofimia , A. Gruttadauria , F. Deirmina , N. Lecis , S. Barella","doi":"10.1016/j.matchar.2025.114839","DOIUrl":"10.1016/j.matchar.2025.114839","url":null,"abstract":"<div><div>This study investigates the microstructural development of commercial low-alloyed AISI 4340 steel through the synergistic application of Binder Jetting and Quenching and Partitioning (QP) processes. The material in the as-sintered condition exhibited significant variations in microstructure and mechanical properties, primarily influenced by the processing route. Carbon content was influenced by the building technique as decarburization was observed at different intensities mainly during the heating stage of sintering, driven by carbothermic reduction. Vacuum-debinding was found to be optimal, leading to the most homogeneous microstructure, predominantly granular bainite with superior hardness and tensile strength. Different QP treatments were optimized considering the decarburization effect on the optimal as-sintered condition, stabilizing 4–8 % retained austenite in a martensitic matrix, with optimal results observed after isothermal holding at either 220 °C or 240 °C for 30 min. These conditions resulted in high UTS values of 1231 MPa and 1151 MPa, respectively, compared to 750 MPa in the as-sintered state. Despite high tensile properties, A% was limited by the presence of residual porosity. This study highlights the critical importance of controlled debinding and sintering atmospheres as well as decarburization-informed QP treatments in achieving desirable microstructural and mechanical properties in additively manufactured AISI 4340 steel components.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114839"},"PeriodicalIF":4.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.matchar.2025.114838
Graeme J. Francolini, T. Benjamin Britton
For materials scientists and engineers, the extreme and unusual conditions in which meteorites and their microstructures form allow for insight into materials which would exist at the edge of our thermomechanical processing abilities. One such microstructure found in low-shock event iron meteorites is Neumann bands. These bands are arrays of lenticular deformation twins that form throughout the FeNi matrix with numerous intersections, resulting in many high stress and strain regions within the material's surface. These regions and the shocks that formed them encourage atypical strain accommodating mechanisms and structural changes of the material. However, investigation of the deformation twin intersections and the microstructural behaviour in and around these regions has been limited. In this work, investigation of these regions in a Campo del Cielo meteorite fragment, with electron backscatter diffraction (EBSD) and forescatter electron (FSE) imaging, revealed two primary findings: high-intensity pattern doubling mirrored across the {110} band at twin-twin intersection and microband formation across the sample surface, suggesting multilayer twinning and constraint of the crystal structure at twin-twin intersection points. Microbands were found to form along the {110} plane and in regions near Neumann bands. The simultaneous existence of Neumann bands (microtwins) and microbands is presented here for a BCC material, and it is believed the Neumann band and microbands formed during different types and/or shock events from one another. The presence of both Neumann bands and microbands within a BCC iron meteorite is previously unreported and may be valuable in furthering our understanding of shock deformation within iron-based materials.
对于材料科学家和工程师来说，陨石及其微观结构形成的极端和不寻常条件，使他们能够深入了解我们热机械加工能力边缘的材料。在低冲击事件铁陨石中发现的一种微结构是诺伊曼带。这些条带是在整个铁镍基体中形成的透镜状变形孪晶阵列，有许多交叉点，从而在材料表面形成许多高应力和高应变区域。这些区域以及形成这些区域的冲击促进了材料的非典型应变容纳机制和结构变化。然而，对变形孪晶交叉以及这些区域内和周围的微观结构行为的研究还很有限。在这项研究中，利用电子反向散射衍射（EBSD）和前向散射电子（FSE）成像技术对 Campo del Cielo 陨石碎片中的这些区域进行了研究，发现了两个主要发现：在孪晶交汇处的{110}带和样品表面的微带形成了高强度的图案加倍镜像，这表明在孪晶交汇点存在多层孪晶和晶体结构约束。微带是沿着{110}平面和靠近诺伊曼带的区域形成的。这里提出了同时存在 Neumann 带（微孪晶）和微带的 BCC 材料，并认为 Neumann 带和微带是在不同类型和/或彼此不同的冲击事件中形成的。在 BCC 铁陨石中同时存在 Neumann 带和微带是以前从未报道过的，这对我们进一步了解铁基材料的冲击变形可能很有价值。
{"title":"Microstructural characterization to reveal evidence of shock deformation in a Campo del Cielo meteorite fragment","authors":"Graeme J. Francolini, T. Benjamin Britton","doi":"10.1016/j.matchar.2025.114838","DOIUrl":"10.1016/j.matchar.2025.114838","url":null,"abstract":"<div><div>For materials scientists and engineers, the extreme and unusual conditions in which meteorites and their microstructures form allow for insight into materials which would exist at the edge of our thermomechanical processing abilities. One such microstructure found in low-shock event iron meteorites is Neumann bands. These bands are arrays of lenticular deformation twins that form throughout the Fe<img>Ni matrix with numerous intersections, resulting in many high stress and strain regions within the material's surface. These regions and the shocks that formed them encourage atypical strain accommodating mechanisms and structural changes of the material. However, investigation of the deformation twin intersections and the microstructural behaviour in and around these regions has been limited. In this work, investigation of these regions in a Campo del Cielo meteorite fragment, with electron backscatter diffraction (EBSD) and forescatter electron (FSE) imaging, revealed two primary findings: high-intensity pattern doubling mirrored across the {110} band at twin-twin intersection and microband formation across the sample surface, suggesting multilayer twinning and constraint of the crystal structure at twin-twin intersection points. Microbands were found to form along the {110} plane and in regions near Neumann bands. The simultaneous existence of Neumann bands (microtwins) and microbands is presented here for a BCC material, and it is believed the Neumann band and microbands formed during different types and/or shock events from one another. The presence of both Neumann bands and microbands within a BCC iron meteorite is previously unreported and may be valuable in furthering our understanding of shock deformation within iron-based materials.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114838"},"PeriodicalIF":4.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.matchar.2025.114848
Xiang D. Zhang , Li Chen , Jian W. Du , Chun Hu , She Q. Wang
Thermal stability and oxidation resistance are crucial factors for evaluating the industrial potential of CrAlSiN coatings. Nevertheless, most of the studies focus on the microstructure and performance of CrAlSiN coatings with nanocomposite structure, the thermal stability, oxidation resistance, and the underlying mechanisms of CrAlSiN solid solution coatings still remain unknown. Here, Cr1-x-zAlxSizN coatings with gradient Si contents (z = 0–0.09) were prepared by arc evaporation. The influence of Si content on microstructure, mechanical properties, thermal stability, and oxidation resistance of CrAlSiN solid solution coatings is thoroughly discussed. The Cr1-x-zAlxSizN coatings are cubic structured up to z = 0.08, whereas the Cr0.37Al0.54Si0.09N coating demonstrates a mixed cubic and hexagonal wurtzite structure. The hardness of cubic Cr1-x-zAlxSizN coatings increases with Si content rises due to solid solution effect and grain refinement, from the 27.7 ± 0.9 GPa of Cr0.46Al0.54N to the 36.1 ± 0.5 GPa of Cr0.38Al0.54Si0.08N. While Cr0.37Al0.54Si0.09N coating shows a declined hardness of 33.5 ± 0.6 GPa resulted from wurtzite formation. Furthermore, the breakage of CrN bonds is suppressed by Si-addition, where the formation temperature of hexagonal Cr2N is enhanced from 1000 °C for Cr0.46Al0.54N to 1100 °C for all Si-containing coatings. Notably, oxidation resistance is also improved by increasing Si content owing to the promoted formation of dense Cr-rich oxide scale, grain refinement, and inhibited thermal decomposition process. After oxidation at 1100 °C for 15 h, Cr0.44Al0.55Si0.01N, Cr0.43Al0.55Si0.02N, Cr0.42Al0.54Si0.04N, Cr0.38Al0.54Si0.08N and Cr0.37Al0.54Si0.09N coatings form oxides with thicknesses of ∼1.20, ∼0.95, ∼0.90, ∼0.90 and ∼ 0.64 μm, compared to the ∼1.49 μm of that on Cr0.46Al0.54N coating.
{"title":"Impact of Si content on the thermal stability and oxidation resistance of cubic structured CrAlSiN coatings","authors":"Xiang D. Zhang , Li Chen , Jian W. Du , Chun Hu , She Q. Wang","doi":"10.1016/j.matchar.2025.114848","DOIUrl":"10.1016/j.matchar.2025.114848","url":null,"abstract":"<div><div>Thermal stability and oxidation resistance are crucial factors for evaluating the industrial potential of CrAlSiN coatings. Nevertheless, most of the studies focus on the microstructure and performance of CrAlSiN coatings with nanocomposite structure, the thermal stability, oxidation resistance, and the underlying mechanisms of CrAlSiN solid solution coatings still remain unknown. Here, Cr<sub>1-x-z</sub>Al<sub>x</sub>Si<sub>z</sub>N coatings with gradient Si contents (z = 0–0.09) were prepared by arc evaporation. The influence of Si content on microstructure, mechanical properties, thermal stability, and oxidation resistance of CrAlSiN solid solution coatings is thoroughly discussed. The Cr<sub>1-x-z</sub>Al<sub>x</sub>Si<sub>z</sub>N coatings are cubic structured up to z = 0.08, whereas the Cr<sub>0.37</sub>Al<sub>0.54</sub>Si<sub>0.09</sub>N coating demonstrates a mixed cubic and hexagonal wurtzite structure. The hardness of cubic Cr<sub>1-x-z</sub>Al<sub>x</sub>Si<sub>z</sub>N coatings increases with Si content rises due to solid solution effect and grain refinement, from the 27.7 ± 0.9 GPa of Cr<sub>0.46</sub>Al<sub>0.54</sub>N to the 36.1 ± 0.5 GPa of Cr<sub>0.38</sub>Al<sub>0.54</sub>Si<sub>0.08</sub>N. While Cr<sub>0.37</sub>Al<sub>0.54</sub>Si<sub>0.09</sub>N coating shows a declined hardness of 33.5 ± 0.6 GPa resulted from wurtzite formation. Furthermore, the breakage of Cr<img>N bonds is suppressed by Si-addition, where the formation temperature of hexagonal Cr<sub>2</sub>N is enhanced from 1000 °C for Cr<sub>0.46</sub>Al<sub>0.54</sub>N to 1100 °C for all Si-containing coatings. Notably, oxidation resistance is also improved by increasing Si content owing to the promoted formation of dense Cr-rich oxide scale, grain refinement, and inhibited thermal decomposition process. After oxidation at 1100 °C for 15 h, Cr<sub>0.44</sub>Al<sub>0.55</sub>Si<sub>0.01</sub>N, Cr<sub>0.43</sub>Al<sub>0.55</sub>Si<sub>0.02</sub>N, Cr<sub>0.42</sub>Al<sub>0.54</sub>Si<sub>0.04</sub>N, Cr<sub>0.38</sub>Al<sub>0.54</sub>Si<sub>0.08</sub>N and Cr<sub>0.37</sub>Al<sub>0.54</sub>Si<sub>0.09</sub>N coatings form oxides with thicknesses of ∼1.20, ∼0.95, ∼0.90, ∼0.90 and ∼ 0.64 μm, compared to the ∼1.49 μm of that on Cr<sub>0.46</sub>Al<sub>0.54</sub>N coating.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114848"},"PeriodicalIF":4.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.matchar.2025.114845
Katika Harikrishna , Abeyram Nithin , M.J. Davidson
Grain size analysis is crucial for understanding material properties, yet traditional manual methods are often time-consuming and labor-intensive. This study presents a novel approach utilizing Python's OpenCV, SciPy, and NumPy libraries for automated microstructure segmentation and grain size analysis of Al + SiC nanocomposites fabricated through powder metallurgy (PM). When segmenting backscattered electron (BSE) images, challenges such as noise, local contrast variations, inaccurate thresholding, fused grains, edge grain removal, and grain boundary separation arise. To address these, advanced image processing techniques were employed: Gaussian filtering reduced noise, and Contrast Limited Adaptive Histogram Equalization (CLAHE) enhanced local contrast, making grain boundaries more distinct. Automated thresholding was performed using Otsu's method to differentiate grains and boundaries, while morphological operations (erosion and dilation) refined the separation of fused grains. Edge grains were excluded using cv2.floodFill(), and the distance transform function clearly delineated grains and boundaries. Connected components analysis was used to identify and label distinct regions in the image, aiding in the determination of the number of grains. The algorithm was tested on multiple BSE images for robustness, with results compared to manual grain size measurements according to ASTM standards. A Bland-Altman plot and Pearson correlation were used to validate the algorithm, showing that the error is within the limits of agreement and the correlation coefficient of 0.98 demonstrates high accuracy in predicting grain sizes, maintaining a reasonable level of precision.
{"title":"Automated microstructural segmentation and grain size measurement of Al + SiC nanocomposites using advanced image processing techniques on backscattered electron images","authors":"Katika Harikrishna , Abeyram Nithin , M.J. Davidson","doi":"10.1016/j.matchar.2025.114845","DOIUrl":"10.1016/j.matchar.2025.114845","url":null,"abstract":"<div><div>Grain size analysis is crucial for understanding material properties, yet traditional manual methods are often time-consuming and labor-intensive. This study presents a novel approach utilizing Python's OpenCV, SciPy, and NumPy libraries for automated microstructure segmentation and grain size analysis of Al + SiC nanocomposites fabricated through powder metallurgy (PM). When segmenting backscattered electron (BSE) images, challenges such as noise, local contrast variations, inaccurate thresholding, fused grains, edge grain removal, and grain boundary separation arise. To address these, advanced image processing techniques were employed: Gaussian filtering reduced noise, and Contrast Limited Adaptive Histogram Equalization (CLAHE) enhanced local contrast, making grain boundaries more distinct. Automated thresholding was performed using Otsu's method to differentiate grains and boundaries, while morphological operations (erosion and dilation) refined the separation of fused grains. Edge grains were excluded using cv2.floodFill(), and the distance transform function clearly delineated grains and boundaries. Connected components analysis was used to identify and label distinct regions in the image, aiding in the determination of the number of grains. The algorithm was tested on multiple BSE images for robustness, with results compared to manual grain size measurements according to ASTM standards. A Bland-Altman plot and Pearson correlation were used to validate the algorithm, showing that the error is within the limits of agreement and the correlation coefficient of 0.98 demonstrates high accuracy in predicting grain sizes, maintaining a reasonable level of precision.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114845"},"PeriodicalIF":4.8,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.matchar.2025.114843
Sarah G. Sanderson , Sajjad Izadpanah Najmabad , Rishabh Sharma , Tyson Neville , Asher Webb , Michael P. Miles , Marko Knezevic , David T. Fullwood
Structural aluminum alloys are often less-than ideal materials for studying sub-grain strain gradients via EBSD, at typical resolution settings. Sharply defined slip bands are not generally observed due to cross-slip, and second-phase particles formed during solidification of work-hardened alloys provide obstacles that disrupt potential structure development, leading to what can seem like random distributions of geometrically necessary dislocations (GNDs). This study considers the roles of length-scale and second-phase particles in sub-grain distributions of AA6016-T4 following deformation. Second-phase particles are shown to play a stronger role than grain boundaries (GBs) in local GND accumulations. The net Burgers vector is used to show the transition from crystallographic-level slip to macro-scale slip as length scale increases, with a corresponding transition in the GND vs. step size graph. A strain gradient crystal plasticity model is applied to assess predictability of the observations. Real 3D structures were extracted, via serial sectioning, following application of different strain paths. Predicted GND and total dislocation evolution closely follows observed values. The model is then used to study the relative contributions of GBs and second-phase particles to GND localization, leading to the conclusion that second-phase particles must be included in the model to reflect observed behavior.
{"title":"Observation and modeling of strain gradients in AA6016 – Influence of length-scale, microstructure, and strain path","authors":"Sarah G. Sanderson , Sajjad Izadpanah Najmabad , Rishabh Sharma , Tyson Neville , Asher Webb , Michael P. Miles , Marko Knezevic , David T. Fullwood","doi":"10.1016/j.matchar.2025.114843","DOIUrl":"10.1016/j.matchar.2025.114843","url":null,"abstract":"<div><div>Structural aluminum alloys are often less-than ideal materials for studying sub-grain strain gradients via EBSD, at typical resolution settings. Sharply defined slip bands are not generally observed due to cross-slip, and second-phase particles formed during solidification of work-hardened alloys provide obstacles that disrupt potential structure development, leading to what can seem like random distributions of geometrically necessary dislocations (GNDs). This study considers the roles of length-scale and second-phase particles in sub-grain distributions of AA6016-T4 following deformation. Second-phase particles are shown to play a stronger role than grain boundaries (GBs) in local GND accumulations. The net Burgers vector is used to show the transition from crystallographic-level slip to macro-scale slip as length scale increases, with a corresponding transition in the GND vs. step size graph. A strain gradient crystal plasticity model is applied to assess predictability of the observations. Real 3D structures were extracted, via serial sectioning, following application of different strain paths. Predicted GND and total dislocation evolution closely follows observed values. The model is then used to study the relative contributions of GBs and second-phase particles to GND localization, leading to the conclusion that second-phase particles must be included in the model to reflect observed behavior.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114843"},"PeriodicalIF":4.8,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.matchar.2025.114846
Zhihao Zhang , Han Bao , Kaiyun Xiang , Yu Zhang , Lipeng Ding , Zhihong Jia , Linzhong Zhuang
The grain refinement of Al-Zn-Mg-Cu alloys is essential for the superplasticity forming of these alloys. In the present work, the influences of MgZn2 particles on the recrystallization and final grain size of Al-5.80Zn-2.10 Mg-1.60Cu-0.2Cr alloy under various over-aging and annealing processes were systematically studied. It was revealed that over-aging at 400 °C effectively promotes the coarsening of MgZn2 particles, facilitating the activation of particle simulated nucleation (PSN) effect, and resulting in equiaxed fine grains. The annealing temperature (400 °C and 480 °C) has no clear influence on the grain sizes of the sample as the recrystallized grain size is primary depend on the volume fraction and size of the MgZn2 particles. The average size for PSN effect is measured as about 200 nm, much smaller than previous literatures. In contrast, over-aging at 260 °C even for sufficient time has a minimal effect on the coarsening of MgZn2 particles. The activation of strain-induced boundary migration (SIBM) gives rise to the formation of elongated coarse grains. The grain size resulting from the SIBM mechanism is highly sensitive to the annealing temperature. The sample over-aging at 400 °C for 14 h and annealing at 480 °C for 120 s is selected as the optimum process as it produces an equiaxed fine grains with average size of 10.4 ± 3.5 μm. These results can provide key information for grain refinement of Al-Zn-Mg-Cu alloys for superplasticity forming.
{"title":"Examining the effect of second phase particles on recrystallization and grain refinement of Al-Zn-Mg-Cu alloy via coupling of over-aging and annealing treatments","authors":"Zhihao Zhang , Han Bao , Kaiyun Xiang , Yu Zhang , Lipeng Ding , Zhihong Jia , Linzhong Zhuang","doi":"10.1016/j.matchar.2025.114846","DOIUrl":"10.1016/j.matchar.2025.114846","url":null,"abstract":"<div><div>The grain refinement of Al-Zn-Mg-Cu alloys is essential for the superplasticity forming of these alloys. In the present work, the influences of MgZn<sub>2</sub> particles on the recrystallization and final grain size of Al-5.80Zn-2.10 Mg-1.60Cu-0.2Cr alloy under various over-aging and annealing processes were systematically studied. It was revealed that over-aging at 400 °C effectively promotes the coarsening of MgZn<sub>2</sub> particles, facilitating the activation of particle simulated nucleation (PSN) effect, and resulting in equiaxed fine grains. The annealing temperature (400 °C and 480 °C) has no clear influence on the grain sizes of the sample as the recrystallized grain size is primary depend on the volume fraction and size of the MgZn<sub>2</sub> particles. The average size for PSN effect is measured as about 200 nm, much smaller than previous literatures. In contrast, over-aging at 260 °C even for sufficient time has a minimal effect on the coarsening of MgZn<sub>2</sub> particles. The activation of strain-induced boundary migration (SIBM) gives rise to the formation of elongated coarse grains. The grain size resulting from the SIBM mechanism is highly sensitive to the annealing temperature. The sample over-aging at 400 °C for 14 h and annealing at 480 °C for 120 s is selected as the optimum process as it produces an equiaxed fine grains with average size of 10.4 ± 3.5 μm. These results can provide key information for grain refinement of Al-Zn-Mg-Cu alloys for superplasticity forming.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"222 ","pages":"Article 114846"},"PeriodicalIF":4.8,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402821","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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