Electrical Switching in Metallic Carbon Nanotubes

We present first-principles calculations of quantum transport which show that the resistance of metallic carbon nanotubes can be changed dramatically with homogeneous transverse electric fields if the nanotubes have impurities or defects. The change of the resistance is predicted to range over more than two orders of magnitude with experimentally attainable electric fields. This novel property has its origin that backscattering of conduction electrons by impurities or defects in the nanotubes is strongly dependent on the strength and/or direction of the applied electric fields. We expect this property to open a path to new device applications of metallic carbon nanotubes.Comment: 4 pages and 4 figure

Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor

We have explored a new mechanism for switching magnetism and superconductivity in a magnetically frustrated iron-based superconductor using spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single crystal Sr$_2$VO$_3$FeAs shows that a spin-polarized tunneling current can switch the Fe-layer magnetism into a non-trivial $C_4$ (2$\times$2) order, not achievable by thermal excitation with unpolarized current. Our tunneling spectroscopy study shows that the induced $C_4$ (2$\times$2) order has characteristics of plaquette antiferromagnetic order in Fe layer and strongly suppressed superconductivity. Also, thermal agitation beyond the bulk Fe spin ordering temperature erases the $C_4$ state. These results suggest a new possibility of switching local superconductivity by changing the symmetry of magnetic order with spin-polarized and unpolarized tunneling currents in iron-based superconductors.Comment: 33 pages, 16 figure

Microstructure and mechanical properties of gas metal arc welded CoCrFeMnNi joints using a 410 stainless steel filler metal

Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES ) for its financial support via the project UID/00667/2020 ( UNIDEMI ). JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT-Fundação para a Ciência e a Tecnologia , I.P., within the scope of Multiannual Financing of R&D Units , reference UIDB/50025/2020-2023 . JS acknowledges the China Scholarship Council for funding the Ph.D. grant ( CSC NO. 201808320394 ). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT - MCTES ) for funding the Ph.D. Grant 2020.07350.BD . This work was supported by the National Research Foundation of Korea (NRF) with a grant funded by the Korea government ( MSIP ) ( NRF-2021R1A2C3006662 ). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT-Fundação para a Ciência e a Tecnologia, I.P. within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT-MCTES) for funding the Ph.D. Grant 2020.07350.BD. This work was supported by the National Research Foundation of Korea (NRF) with a grant funded by the Korea government (MSIP) (NRF-2021R1A2C3006662). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Publisher Copyright: © 2022 The AuthorsThe use of filler materials during fusion-based welding processes is widely used to regulate and modify the composition of the welded joints aiming at producing a desired microstructure and/or achieving an improvement in its mechanical performance. Welding of high entropy alloys is still a new topic and the impact of different filler materials on the microstructure and mechanical properties is yet unknown. In this work, gas metal arc welding of the CoCrFeMnNi high entropy alloy using 410 stainless steel as a filler wire was performed. The microstructural evolution of the welded joints was evaluated by optical microscopy, scanning electron microscopy aided by electron backscattered diffraction, high energy synchrotron X-ray diffraction and thermodynamic calculations. Meanwhile, the mechanical behavior of the welded joint, as well as the local mechanical response were investigated with microhardness mapping measurements and with non-contact digital image correlation during tensile loading to failure. The weld thermal cycle promoted solid state reactions in the heat affected zone (recovery, recrystallization and grain growth), which impacted the microhardness across the joint. The role of the 410 stainless steel filler material in the solidification path experienced by the fusion zone was evaluated using Scheil-Gulliver calculations, and a good agreement with the experimentally observed phases was observed. Despite the addition of the 410 stainless steel filler was not conducive to an increase in the fusion zone hardness, the associated bead reinforcement promoted an improvement in both the yield and tensile strengths of the joint compared to a similar weld obtained without filler material (355 vs 284 MPa and 641 vs 519 MPa, respectively). This allows to infer that the addition of filler materials for welding high entropy alloys is a viable method for the widespread use of these novel materials. In this work, by coupling microstructure and mechanical property characterization, a correlation between the processing conditions, microstructure and mechanical properties was obtained providing a wider basis for promoting the application of gas metal arc welding of high entropy alloys for industrial applications.publishersversionpublishe

Microstructure and mechanical properties of gas metal arc welded CoCrFeMnNi joints using a 308 stainless steel filler metal

Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT-MCTES) for funding the Ph.D. Grant 2020.07350.BD. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2022R1A5A1030054). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P. , in the scope of the projects LA/P/0037/2020 , UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394 ). JGL acknowledges Fundação para a Ciência e a Tecnologia (FCT-MCTES) for funding the Ph.D. Grant 2020.07350.BD . This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) ( NRF-2022R1A5A1030054 ). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Publisher Copyright: © 2022 The AuthorsIn this paper, gas metal arc welding of a CoCrFeMnNi high entropy alloy was performed using 308 stainless steel filler wire. Electron backscatter diffraction and synchrotron X-ray diffraction were used to determine the microstructural evolution, while microhardness mapping and non-contact digital image correlation were employed to assess the local mechanical response across the welded joints. Further, thermodynamic calculations were implemented to support the understanding of the microstructure evolution. Through a systematic analysis of the microstructure evolution and mechanical properties, it is established a correlation between welding process, microstructure and mechanical properties. Besides, this work lays the foundations for the use of low-cost arc-based welding technologies for successful joining and application of welded joints based on high entropy alloys.publishersversionpublishe

Deformation behavior and strengthening effects of an eutectic AlCoCrFeNi2.1 high entropy alloy probed by in-situ synchrotron X-ray diffraction and post-mortem EBSD

Funding Information: JS, JGL, and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges FCT – MCTES for funding the Ph.D. grant 2020.07350.BD. JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P. in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872from the EU Framework Programme for Research and Innovation HORIZON 2020. HSK acknowledges the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2021R1A2C3006662, NRF-2022R1A5A1030054). Yeon Taek Choi was supported by the Basic Science Research Program “Fostering the Next Generation of Researcher” through the NRF funded by the Ministry of Education [grant number 2022R1A6A3A13073824]. The raw/processed data required to reproduce the above findings cannot be shared at this time as the data also forms part of an ongoing study. Funding Information: JS, JGL, and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394 ). JGL acknowledges FCT – MCTES for funding the Ph.D. grant 2020.07350.BD . JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia , I.P., in the scope of the projects LA/P/0037/2020 , UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020 . HSK acknowledges the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) ( NRF-2021R1A2C3006662 , NRF-2022R1A5A1030054 ). Yeon Taek Choi was supported by the Basic Science Research Program “Fostering the Next Generation of Researcher” through the NRF funded by the Ministry of Education [grant number 2022R1A6A3A13073824 ]. Publisher Copyright: © 2023 The AuthorsIn this work, high energy synchrotron X-ray diffraction was used during tensile testing of an as-cast eutectic AlCoCrFeNi2.1 high entropy alloy. Aside, from determining for the first time the volume fractions of existing phases, we further detail their role on the alloy deformation behavior. The two major phases, a soft disordered FCC and a hard ordered B2 BCC, were observed to exhibit a stress partitioning effect which can be used to modulate the mechanical response of the material based on the relative volume fraction of each phase. Dislocation density analysis revealed that the soft FCC phase had a significantly higher dislocation density right after the onset of plastic deformation. This is attributed to the existence of strain gradients across the lamellar structure, where the hard B2 BCC prevents free deformation of the FCC phase. Nonetheless, despite the increase of the dislocation density in the soft FCC phase, calculations of the strengthening effects induced by generation of dislocations are more significant in the hard B2 BCC phases, as this phase is primarily responsible for the strength increase in the alloy. Besides, the evolutions in dislocation density of the soft FCC and hard B2 BCC phases during tensile deformation obtained from synchrotron X-ray diffraction data are consistent with the evolution of KAM determined by EBSD characterization. Also, lattice strain analysis across two principal directions (parallel and perpendicular to the loading axis) reveals that for these specific orientations there is a preferential deformation of the hard FCC planes which can be related to the deformation response of specific lattice planes at distinct orientations, as well as to the phase partitioning stress behavior.publishersversionpublishe

High resolution angle resolved photoemission studies on quasi-particle dynamics in graphite

We obtained the spectral function of the graphite H point using high resolution angle resolved photoelectron spectroscopy (ARPES). The extracted width of the spectral function (inverse of the photo-hole lifetime) near the H point is approximately proportional to the energy as expected from the linearly increasing density of states (DOS) near the Fermi energy. This is well accounted by our electron-phonon coupling theory considering the peculiar electronic DOS near the Fermi level. And we also investigated the temperature dependence of the peak widths both experimentally and theoretically. The upper bound for the electron-phonon coupling parameter is ~0.23, nearly the same value as previously reported at the K point. Our analysis of temperature dependent ARPES data at K shows that the energy of phonon mode of graphite has much higher energy scale than 125K which is dominant in electron-phonon coupling.Comment: 9 pages, 8 figures, accepted for publication in Phys. Rev.

Synergistic effects of Monel 400 filler wire in gas metal arc welding of CoCrFeMnNi high entropy alloy

Funding Information: JS and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT-Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). This work was supported by the National Research Foundation of Korea (NRF) with a grant funded by the Korea government (MSIP) (NRF-2021R1A2C3006662). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Funding Information: JS and JPO acknowledge Funda\u00E7\u00E3o para a Ci\u00EAncia e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 ( UNIDEMI ). JPO acknowledges the funding of CENIMAT/ i3N by national funds through the FCT- Funda\u00E7\u00E3o para a Ci\u00EAncia e a Tecnologia , I.P., within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023. JS acknowledges the China Scholarship Council for funding the Ph.D. grant ( CSC NO . 201808320394 ). This work was supported by the National Research Foundation of Korea (NRF) with a grant funded by the Korea government (MSIP) (NRF-2021R1A2C3006662). The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC . The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020 . Publisher Copyright: © 2024 The AuthorsWeldability plays a crucial role in the journey of high entropy alloys towards their engineering applications. In this study, gas metal arc welding was performed to join an as-rolled CoCrFeMnNi high entropy alloy using Monel 400 as the filler wire. The present research findings demonstrate a favorable metallurgical chemical reaction between the Monel 400 filler and the CoCrFeMnNi high entropy alloy, resulting in compositional mixing within the fusion zone that promotes a solid-solution strengthening effect, counteracting the typical low hardness associated to the fusion zone of these alloys. The weld thermal cycle induced multiple microstructure changes across the joint, including variations in the grain size, existing phases and local texture. The grain size was seen to increase from the base material toward the fusion zone. An FCC matrix and finely sparse Cr-Mn-based oxides existed in both base material and heat affected zone, while in the fusion zone new FCC phases and carbides were formed upon the mixing of the Monel 400 filler. The role of the filler material on the fusion zone microstructure evolution was rationalized using thermodynamic calculations. Texture shifted from a γ-fiber (in the base material) to a strong cubic texture in the fusion zone. Digital image correlation during tensile testing to fracture coupled with microhardness mapping revealed that, stemming from the process-induced microstructure changes, the micro and macromechanical response differed significantly from the original base material. This study successfully established a correlation between the impact of the process on the developed microstructural features and the resultant mechanical behavior, effectively assessing the processing-microstructure-properties relationships towards an improved understanding of the physical metallurgy associated to these advanced engineering alloys. In conclusion, this work provides an important theoretical framework and practical guidance for optimizing the engineering applications of high entropy alloys.publishersversionpublishe

Fabrication of spatially-variable heterostructured CoCrFeMnNi high entropy alloy by laser processing

JS and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES ) for its financial support via the project UID/00667/2020 (UNIDEMI). JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394 ). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2022R1A5A1030054 ). Funding Information: Interestingly, DP-HEA exhibits higher maximum strength (≈570 vs. ≈ 693 MPa) and ductility (≈11.0 vs. ≈ 18.9 %) compared to SP-HEA (refer to Fig. 5 a)). This difference can be mainly attributed to the distinct spatial heterogeneity in the resulting microstructures, leading to different interactions between the soft and hard domains. Typically, in heterogeneous structures, both the soft and hard domains undergo elastic deformation first when subjected to external loading, similar to conventional homogeneous materials. However, as the loading increases, the soft domain will preferentially initiate plastic deformation while the hard domain not, leading to the existence of a mechanical incompatibility. This results in the generation of geometrically necessary dislocations (GNDs) near the interface between the soft and hard domains, which accumulate at the interface and induce hetero-deformation induced (HDI) strengthening [ 38–40]. Theoretically, heterogeneous materials are characterized by significant strength differences between soft and hard domains. The larger the strength differences between domains, the higher mechanical incompatibility, and higher back stresses accumulate in the soft domains, leading to enhanced HDI strengthening and strain hardening. So far, numerous researchers have successfully utilized these strengthening concepts to fabricate spatially heterogeneous structural materials with excellent mechanical properties [ 41–46]. However, the final mechanical properties of the fabricated spatially heterogeneous materials can be affected by a variety of factors, such as alloy composition, purity of the original materials, synthesis methods, and subsequent processing techniques employed in the fabricated spatially heterogeneous structures. Thus, direct one-to-one property comparisons between the present pulsed laser-processed spatial heterogeneous materials (SP-HEA and DP-HEA) and other spatial heterogeneous materials produced using alternative fabrication methods would lead to biased comparisons. Therefore, in this case, the comparison with spatially heterogeneous materials made by other processes is not performed. Instead, a comparative analysis was performed, focusing on the same original as-rolled CoCrFeMnNi used as a benchmark for mechanical properties [37]. The present results demonstrate that SP-HEA and DP-HEA exhibit superior performance in terms of ductility (18.9% vs. 11.0% vs. 9.5%, for SP-HEA, DP-HEA, and as-rolled CoCrFeMnNi, respectively), albeit with reduced strength when compared to the as-rolled CoCrFeMnNi (693 MPa vs. 570 MPa vs. 947 MPa), showcasing the potential application of these two heterostructured materials (SP-HEA and DP-HEA) for structural applications where depending on the expected loading conditions, one can chose either processing methodology. An intriguing observation arises from the tensile stress-strain curves, specifically in the elastic deformation stage, where the slope of SP-HEA is discernibly lower than that of DP-HEA. This discrepancy suggests that, under equivalent external loading, SP-HEA undergoes a more substantial deformation. To elucidate this behavior, delving into the dynamics of loading transfer and the dimensions of the load-bearing area for both SP-HEA and DP-HEA is necessary. In materials featuring both soft and hard regions, the initial load during external loading is borne by the softer regions due to their inherent characteristics. As these soft regions yield, the load gradually transfers to the harder regions. Additionally, considering the load-bearing area, a larger object subjected to the same external load experiences relatively lower force per unit area. Therefore, to achieve an equivalent deformation, the load applied to the larger load-bearing area must surpass that applied to the smaller force-bearing area. Applying these principles to SP-HEA and DP-HEA, the stress-strain curve reveals a lower elastic slope for SP-HEA, indicating higher deformation under the same external load. This can be primarily attributed to the fact that the area of relatively soft regions in DP-HEA is nearly twice that of SP-HEA. When subjected to the same external load, the initially stressed areas—represented by the FZ—exhibit varying force per unit areas due to the doubled FZ area in DP-HEA. Consequently, the external load required to induce yielding in the soft region of DP-HEA is significantly greater than that in SP-HEA, thereby contributing to the observed difference in elastic slopes. Returning to the current work, the strength (hardness) difference between the soft and hard domains in SP-HEA is significantly larger than in DP-HEA, 100 vs 252 HV0.2, respectively. Therefore, the mechanical performance of SP-HEA would be expected to be better than that of DP-HEA. However, DP-HEA demonstrates superior mechanical properties in terms of both strength and plasticity than SP-HEA. An initial inference is that the large strength difference (≈210 vs. ≈400 HV0.2) between the soft domain (FZ) and the hard domains (rolled BM) in SP-HEA results in massive mechanical incompatibility at the interface. The highly concentrated strain gradient leads to a large accumulation of dislocations at the interface, inducing stress concentration and crack initiation, ultimately resulting in failure at the soft-hard interface. This inference is supported by the observed fracture locations of SP-HEA, as indicated in Fig. 5 b1). On the contrary, the improved mechanical performance of DP-HEA can be attributed to its relatively uniform distribution of heterogeneity at the microstructure level, with a small strength difference between the hard and the soft domains (≈230 vs ≈ 210 HV0.2). This minimizes the mechanical interactions between them and reduces the potential for stress concentrations. Additionally, this more homogeneous microstructure distribution allows for better stress absorption and dispersion, enhancing the material's toughness and ductility. These factors collectively contribute to the improved mechanical properties of DP-HEA, which is further corroborated by the observed ductile fracture mode with numerous dimples on the fracture surface of Fig. 5 b2). Here, a special explanation is needed for the states of stress concentration in heterostructured materials. It is known that during the plastic deformation of heterostructured materials, the hetero zones deform in-homogeneously, generating back stresses in the soft zones and forward stresses in the hard zones. Back stress originates from the accumulation of dislocations in the soft zone, which will act to impede dislocation slip in the soft zone promoting a strain-hardening effect. Forward stresses are created in the hard zone due to stress concentrations at the zone boundary caused by dislocation pileup. For heterostructured materials, HDI strengthening is typically the result of the synergistic effect of both back and forward stresses: the back stresses act to enhance the HDI strengthening, while the forward stresses act to limit the HDI strengthening by assisting the plastic deformation in the hard zones. Therefore, compared to DP-HEA, where the difference between the soft and hard gradients is relatively small (≈100 vs ≈ 252 HV0.2), the high dislocation density generated in the soft zone of SP-HEA (refer to Fig. 2 b)) causes a high stress concentration that occurs at the soft/hard interface, which inevitably generates high forward stresses in the hard domain. As a result, the higher forward stresses in SP-HEA weaken the HDI strengthening in a more abrupt way in DP-HEA. Therefore, a significant difference in hardness between the soft and hard domains can lead to high stress concentrations at the interface, increasing the risk of crack initiation and eventually fracture. Additionally, excessive stress concentration can induce high forward stresses within the hard domain, which in turn weakens the HDI strengthening effect. Thereby, the magnitude of hardness difference is just one factor affecting HDI strengthening, and the actual material performance is determined by the interaction of multiple factors. Thus, the exceptional mechanical properties observed in DP-HEA can be attributed to the combined effects of multiple factors. While the introduction of back stresses theoretically suggests the possibility of stress concentration, DP-HEA exhibits a more balanced microstructural distribution, leading to improved stress absorption and dispersion. Additionally, the smaller strength disparities between the soft and hard domains contribute to reduced mechanical incompatibility. In DP-HEA, there exists a relatively moderate hardness difference between the soft and hard domains, effectively reducing the back stress from the hard zone. Furthermore, the processing conditions, involving an optimized microstructure, play a crucial role in alleviating this stress concentration effect. These conditions further enhance the material's strength and ductility. This complex interplay of factors highlights the intricate relationship between microstructure and mechanical performance in heterogeneous materials. In addition, through a comparative analysis of two spatially heterogeneous materials (SP-HEA and DP-HEA) prepared using different laser processing techniques, it has been confirmed that the applicability of the back stresses strengthening effect (HDI strengthening) depends on the specific characteristics of the material and the associated processing conditions. Here, it is worth mention that, the current work was focus on comparing and analyzing the microstructural characteristics and mechanical properties between the two distinct spatially heterogeneous structures (SP-HEA and DP-HEA). However, future endeavors will primarily concentrate on systematically investigating a broader range of laser parameters to fabricate spatially-variable heterostructured CoCrFeMnNi high entropy alloy through laser processing. This expanded exploration aims to gain a more comprehensive understanding of how different laser parameters impact the microstructure and mechanical properties of CoCrFeMnNi high entropy alloy.JS and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JS, ACB and JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT-Fundação para a Ciência e a Tecnologia, I.P. within the scope of Multiannual Financing of R&D Units, reference LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2022R1A5A1030054). Publisher Copyright: © 2024 The Author(s)This study investigates the fabrication of spatially-variable heterostructured CoCrFeMnNi high entropy alloy (HEA) using pulsed laser processing. Two distinct fabrication approaches, involving single-(SP) and double-sided (DP) laser passes, were employed. Microstructural characterization through electron backscatter diffraction revealed significant differences. SP-HEA exhibited a spatially heterogeneous microstructure with coarse columnar grains, while DP-HEA displayed a sandwich-like structure with fine equiaxed recrystallized grains. Microhardness mapping demonstrated a gradient trend in SP-HEA, with the fusion zone exhibiting the lowest hardness and the base material the highest. In contrast, DP-HEA displayed an overall soft-hard-soft structure. Tensile testing revealed distinct mechanical responses, with DP-HEA exhibiting higher strength and ductility compared to SP-HEA. The improved performance of DP-HEA was attributed to a more uniform distribution of heterogeneity, minimizing mechanical interactions between soft and hard domains. Moreover, corrosion resistance was assessed, showing that DP-HEA outperformed SP-HEA and non-processed material, suggesting superior stability in corrosive environments. These findings highlight the profound influence of fabrication parameters on the microstructure and mechanical properties of spatially-variable heterostructured HEAs. The study contributes valuable insights for material design and applications based on CoCrFeMnNi high entropy alloys.publishersversionpublishe