Columnar Structure Research Articles

Effect of Cu content on microstructure and properties of Ti-6Al-4V alloy fabricated by double-wire arc additive manufacturing

To solve the formation of coarse columnar β grains from Ti-6Al-4 V parts fabricated by wire + arc additive manufacturing, this study adds Cu element for in-situ alloying, effectively suppressing the growth of columnar grains and further enhancing properties. The results show that an addition of Cu element suppresses the lateral growth of β grains, eliminating the columnar structure of β grains. Compared with the Ti-6Al-4 V component, the original β grains in the Ti-6Al-4 V-10Cu component exhibit a refinement of 96 %. With an increase of Cu content, the phase structure of α-Ti transitions from lamellar to needle-like and eventually to equiaxed crystal structure. Moreover, as the Cu content rises, the precipitation of Ti2Cu increases, leading to precipitation strengthening and enhancing the microhardness. The average strength of the Ti-6Al-4 V-10Cu, Ti-6Al-4 V-11.7Cu, and Ti-6Al-4 V-15.7Cu walls is increased by 35.5 %, 56.9 %, and 71.6 %, respectively, compared with the Ti-6Al-4 V wall. The ultimate tensile strength is enhanced by 34.9 %, 49.5 %, and −1.4 %, respectively. However, the elongation is reduced by 48.6 %, 63.2 %, and 75.6 %, respectively.

Modification of ZrO2 ceramic by continuous and pulsed electron beams in the forevacuum pressure range

We describe our study of the treatment of ceramics based on zirconium dioxide (ZrO2), partially stabilized with yttrium oxide (Y2O3) (5.15 % wt.), by continuous and pulsed electron beams in the forevacuum pressure range. We find that continuous electron beam treatment at certain heating rates can lead to changes in the surface structure, with increase in roughness and change in crystalline phase composition. High heating rate leads to increase in the cubic phase of ZrO2. The results of irradiation by a pulsed electron beam depends on the pulse energy density and pulse power of the beam, with noticeable changes in the surface characteristics when the energy density reaches about 10 J/cm2; increased roughness of the ceramic surface is observed at this energy density. Further increase in pulse energy density (>10 J/cm2) and/or power can lead to increase in roughness by an order of magnitude. A change in color of the ceramic surface and formation of a layer with a columnar structure is observed when the energy density reaches 21 J/cm2 at a pulse power of 320 kW. These results show the suitability of electron beam treatment for controlled modification of zirconium dioxide ceramic materials.

Synthesis, crystal structure and properties of poly[di-μ3-chlorido-di-μ2-chlorido-bis[4-methyl-N-(pyridin-2-ylmethylidene)aniline]dicadmium(II)

The title coordination polymer with the 4-methyl-N-(pyridin-2-ylmethylidene)aniline Schiff base ligand (L, C13H12N2), [Cd2Cl4(C13H12N2)] n (1), exhibits a columnar structure extending parallel to [100]. The columns are aligned in parallel and are decorated with chelating L ligands on both sides. They are elongated into a supramolecular sheet extending parallel to (01\overline{1}) through π–π stacking interactions involving L ligands of neighbouring columns. Adjacent sheets are packed into the tri-periodic supramolecular network through weak C—H...Cl hydrogen-bonding interactions that involve the phenyl CH groups and chlorido ligands. The thermal stability and photoluminescent properties of (1) have also been examined.

Effect of TiB2 on the microstructure and mechanical properties of TiAl alloy produced by laser direct energy deposition

A Ti-48Al-2Cr-2Nb alloy was prepared by laser directed energy deposition (DED). The microstructure of the DED-produced Ti-48Al-2Cr-2Nb alloy exhibited a coarse columnar structure along the building direction. Through a combination of experiment and numerical simulation, the temperature gradient and solidification rate of the single-track sample were calculated theoretically. The columnar to equiaxed transition (CET) behavior of molten pool solidification was quantitatively analyzed, and the microstructure transition diagram was established. The effect of TiB2 on the microstructure and mechanical properties of the TiAl alloy was investigated. The columnar changed to equiaxed grains in the vertical cross section by adding nanometer-sized TiB2 particles and the microstructure was significantly refined. The grain size was reduced from 48.5 μm to 4.9 μm. Some equiaxed γ grains were distributed around the banded TiB2. The compressive properties were improved from 628.4 MPa to 698.8 MPa by adding nanometer-sized TiB2 particles. Finally, the solidification behavior and the microstructure refinement mechanism caused by the addition of TiB2 particles were discussed.

Effect of combined additions of Sc, Zr and Ti on hot-cracking resistance and precipitation behaviour in Al-Mg alloy by L-PBF

The request for high-performance aluminum components prompts research into innovative alloys compatible with laser-based additive manufacturing processes, leveraging grain refiners in their composition to mitigate hot-cracking and enhance strength. While the addition of Sc and Zr in Al-Mg alloys has been widely investigated, the high cost and supply risks associated with Sc necessitate reducing its amount and replacing, at least partially, with other inoculants. In this preliminary study, the amount of Sc replaceable with different concentrations of Zr or Ti is evaluated investigating the laser powder bed fusion processability of three powder feedstocks: a pre-alloyed Al-Mg-Zr-Sc powder, a blend of the previous alloy with addition of Zr particles, and a further blend of an alloy depleted of Zr with added Ti particles. The experimental analyses on the laser-processed alloys showed that the standard and the Zr-enriched alloys featured a bimodal microstructure free from cracks with fine equiaxed grains at the edge of the molten pools and coarser grains at their centers. In the alloy variant depleted in Zr with addition of Ti particles a columnar structure was observed and hot-cracks appeared. Thermodynamic simulations of phase formation allowed defining the precipitation kinetics during solidification and direct aging, showing increased precipitation in alloys with higher Zr content, while the presence of Ti resulted in sluggish precipitation. Experimental aging tests demonstrated significant increases in microhardness, with peak values of the modified alloys achieved after 12 h at 375 °C.

Effect of heat treatment on the microstructure and recrystallization of an SLM nickel-based superalloy

Heat treatment is essential for selective laser melting (SLM) of nickel-based superalloys. However, the conventional solution heat treatment method of cast superalloys usually leads to serious recrystallization in the samples. The recrystallized grain boundaries under high-temperature conditions reduce the strength of the alloy, which hinders their widespread applications in aerospace. In this work, a nickel-based superalloy with high γ′ content fabricated by SLM was heat-treated at different solution temperatures. The microstructure of the alloy in different heat-treated states was also characterised. A sub-solvus heat treatment was proposed, which can effectively reduce residual stress and inhibit recrystallization. The microstructure showed that the dislocation density was significantly reduced and recrystallized after the solution heat treatment at 1285 ℃/2 h+1290 ℃/2 h+1295 ℃/4 h and 1250 ℃/0.5 h, and the proportion of recrystallization were 60.0 % and 42.9 %, respectively. However, after sub-solvus heat treatment at 1240 °C/0.5 h, the sample dislocation density decreased and the volume fraction of recrystallization (3.2 %) was slightly higher than that of the as-SLM sample (2.5 %). The sample maintained a strong cubic texture in the build direction. After sub-solvus + aging heat treatment, the microstructure maintained a columnar grain structure. The γ/γ′ interfacial dislocation networks and dislocations pile-up were the main dislocation configurations.

The adsorption of cerium on synthetic δ-MnO2: Implications for Ce uptake behavior of hydrogenetic and early diagenetic ferromanganese nodules from the Western Pacific

Cerium (Ce) anomalies can be used to distinguish diagenetic and hydrogenetic nodules, making them an important discriminator for the genesis of marine ferromanganese nodules. To understand the enrichment and adsorption mechanisms of Ce in different types of ferromanganese nodules, we conducted mineralogical and geochemical studies on ferromanganese nodule layers formed through both hydrogenetic and early diagenetic processes as well as adsorption experiments on synthetic δ-MnO2 to monitor the Ce uptake during the different processes. The major and trace element contents of natural ferromanganese nodule layers were investigated by SEM, EPMA and LA-ICP-MS analysis. The marine nodule studied in this study consisted of a core of fish tooth and a rim that could be divided into the hydrogenetic (type I) and early diagenetic (type II) layers based on their mineralogy and Mn/Fe ratios. The Mn oxide mineral assemblage is composed of todorokite, buserite, birnessite, and vernadite (δ-MnO2) and occurred in both type I and II layers. The type I layer has laminated structures with a low Mn/Fe ratio (1.1–3.2; averaging at 1.7), and low Cu, Ni and Mg contents consistent with a hydrogenetic genesis. The type II layer has a columnar and stromatolitic structure with a high Mn/Fe ratio (5.1–54.0; averaging at 23.3) and high Cu, Ni and Mg contents that are similar to early diagenetic nodules. The ΣREE contents in type I and type II layers are 1405–3506 ppm (averaging at 2091 ppm) and 199–1232 ppm (averaging at 674 ppm), respectively, indicating that the REE is enriched in the hydrogenetic type I layers. Strong positive Ce anomalies are present type I layers ranging from 1.2 to 2.5 (averaging 1.9), but only slightly positive are seen in type II ranging from 0.4 to 2.4 (averaging at 1.0). Synthetic experiments to monitor the Ce uptake process show that Ce can be adsorbed onto δ-MnO2 with the XRD and FTIR patterns suggesting that the structure of δ-MnO2 did not change significantly, consistent with Ce behavior in hydrogenetic nodules. The results suggest that Ce is predominantly concentrated in hydrogenetic nodules in an oxic environment, whereas in the early diagenetic layer, there is less oxidation and fixation of Ce due to the suboxic conditions. Our findings are consistent with Ce anomalies in marine Fe-Mn nodules being the result of Mn oxide oxidation adsorption and then fixation (oxidation) after adsorption.

Structure and corrosion properties of multilayer metal/nitride/oxide ceramic coatings formed on austenitic-martensitic steel by magnetron deposition

The design of protective coatings preventing the degradation and failure of austenitic steels in humid climate is a relevant issue. In this work, a conventional magnetron sputtering method was utilized in order to fabricate a four-layer Ni/Al-Si-N/Ni/Al-Si-O coating onto austenitic-martensitic steel. At the first stage of deposition, a three-layer coating was formed in an Ar+N2 atmosphere using a mosaic target (Ni or Al-Si), while the second stage included the deposition of the outer ceramic Al-Si-O layer in an Ar+O2 gas mixture. The studies of the structure, hardness, adhesion strength and electrochemical behavior (in 3.5 wt.% NaCl) of the «coating/steel» system were performed by means of X-ray Diffraction, electron microscopy, mechanical (indentation and scratch) tests and electrochemical impedance spectroscopy. The ceramic Al-Si-O layer exhibits an amorphous structure. The adjacent nickel layers have submicrocrystalline columnar grains. The ceramic Al-Si-N layer possesses a nanocrystalline columnar structure based on AlN + Si3N4 phases. Hardness behavior of the multilayer coating varies nonmonotonically due to a contribution of the soft amorphous phase in the upper surface layer and high-strength nanocrystalline phases in the underlying sublayers. It has been revealed that as-deposited multilayer coating decreases a corrosion rate of the substrate. The layered structure of the coating hinders the transport and diffusion of chloride ions to the substrate and decreases the corrosion rate of the substrate. However, a transport of chloride ions into the inner layers of the coating may occur through the microstructural defects preserved in the amorphous Al-Si-O layer. The scheme describing an initiation of corrosion damage and formation of corrosion products under critical corrosion conditions was proposed.

Study on Microstructure and Tribological Mechanism of Mo Incorporated (AlCrTiZr)N High-Entropy Ceramics Coatings Prepared by Magnetron Sputtering.

(AlCrTiZrMox)N coatings with varying Mo content were successfully prepared using a multi-target co-deposition magnetron sputtering system. The results reveal that the Mo content significantly affects the microstructure, hardness, fracture toughness, and tribological behavior of the coatings. As the Mo content in the coatings increases gradually, the preferred orientation changes from (200) to (111). The coatings consistently exhibit a distinct columnar structure. Additionally, the hardness of the coatings increases from 24.39 to 30.24 GPa, along with an increase in fracture toughness. The friction coefficient is reduced from 0.72 to 0.26, and the wear rate is reduced by 10 times. During the friction process, the inter-column regions of the coatings are initially damaged, causing the wear track to exhibit a wavy pattern. Greater frictional heat is generated at the crest of the wave, resulting in the formation of a MoO2 lubricating layer. The friction reaction helps to reduce the shear force during friction, demonstrating the lower friction coefficient of the (AlCrTiZrMox)N coatings. Both the hardness and fracture toughness work together to reduce the wear rate, and the (AlCrTiZrMox)N coatings show excellent wear resistance. Most notably, although the columnar structure plays a negative role in the hardness, it contributes greatly to the wear resistance.

Process Parameter Optimization of Directed Energy Deposited QT17‐4+ Steel

AbstractThe feasibility of using argon‐atomized QT 17‐4+ stainless steel powder for directed energy deposition (DED) additive manufacturing is studied. The QT 17‐4+ steel is a novel martensitic steel designed based on the compositional modification of the standard 17‐4 precipitation‐hardened (PH) stainless steel. This modification aims to achieve better mechanical properties of as‐deposited components compared to the heat‐treated wrought 17‐4PH steel. In this study, QT 17‐4+ steel powder is used for DED, for the first time. The influence of laser power, laser scan speed, powder feed rate, and hatch overlap on the density is studied. The central composite design is used to determine the experimental matrix of these factors. The response surface methodology is used to obtain the empirical statistical prediction model. Both columnar and equiaxed parent austenite grain structures are observed. X‐ray diffraction analyses reveal a decrease in the percentage of retained austenite from 19% in the powder to 5% after DED. The microhardness of the DED processed sample in the as‐deposited state is slightly higher than that of wrought 17‐4PH steel either solution‐annealed or H900‐aged. A higher 0.2% yield strength, a lower ultimate tensile strength, and lower elongation are observed for the vertically printed test sample, when compared to the horizontal one.

Influence of synchronized pulse bias on the Microstructure and Properties of CrSiN nano-composite ceramic films deposited by MIS-HiPIMS

In this study, CrSiN nano-composite ceramic films with optimized structure were prepared at low temperature using MIS-HiPIMS technique, owing to improved utilization of the high ionization characteristic of HiPIMS under specially designed synchronized pulsed-bias working mode. The correlations of the synchronized pulsed-bias width, the chemical composition, microstructure evolution, mechanical properties and tribological behaviors were studied systematically. According to the results, the waveforms of the pulsed bias experienced obvious fluctuating periods, indicating fluctuating intensities of positive ions arrived at the substrates. Meanwhile, the fluctuating duration increased with increasing synchronized pulse-width, providing an effective way of adjusting the energetic-ion flux for improved bombardment of the growing film. Therefore, obvious microstructure refinement of the as-deposited CrSiN films had been achieved. Due to optimized ion bombardment, the CrSiN films evolved from a coarse and transgranular columnar structure to a more densified columnar structure with the mixture phases of hcp-Cr2N, fcc-CrN as well as a-Si3N4. Moreover, the hardness and elastic modulus of the CrSiN films were also elevated significantly, to the maximum values of 20.2 GPa and 348.3 GPa, respectively. Furthermore, with the best mechanical properties as well as the highest density, the optimized CrSiN film deposited at 400 μs also displayed the most excellent wear resistance, with the wear rate as low as 9.1 × 10−16 m3/N.m. This study not only proposes a method of optimizing the structure and tribological properties of CrSiN nano-composite ceramic films at relatively low temperature, and also enriches the property database of CrSiN films which could expand their application in fields involving thermal-sensitivity materials.

Selective laser melting of Hastelloy-X alloy and cerium oxide reinforced Hastelloy-X composite: Microstructural examination and corrosion behavior

The study investigated the microstructures and corrosion behaviors of Hastelloy X (HX) and HX reinforced by cerium oxide particles (HX-C) produced by selective laser melting (SLM) and compared to the wrought equivalent (HX-W). The aim was to eliminate hot cracking and investigate the HX's corrosion behavior in the presence of cerium oxide particles. The HX samples showed fine cellular and columnar solidification structures with uniform-size sub-cells and severe microcracking. Incorporating cerium oxide particles (1 wt%) resulted in finer and relatively equiaxed grains without microcracking. The HX-W alloy contained a micron-sized carbide (Mo-rich M6C type) within the matrix. The HX-C sample displayed higher porosities compared to the HX sample (1.8 % against 0.3 %). Potentiodynamic polarization and electrochemical impedance spectroscopy tests were conducted in a standard NaCl solution at temperatures of 25, 50, and 70 °C to assess the corrosion behavior of Hastelloy samples. The HX-C matrix showed superior corrosion resistance compared to the HX-W and HX samples due to its finer grain structure and stable passive layer formation. Cerium oxide particles were found to be efficient in decreasing hot cracking and improving corrosion resistance.

Minicolumn-Based Episodic Memory Model With Spiking Neurons, Dendrites and Delays.

Episodic memory is fundamental to the brain's cognitive function, but how neuronal activity is temporally organized during its encoding and retrieval is still unknown. In this article, combining hippocampus structure with a spiking neural network (SNN), a new bionic spiking temporal memory (BSTM) model is proposed to explore the encoding, formation, and retrieval of episodic memory. For encoding episodic memory, the spike-timing-dependent-plasticity (STDP) learning algorithm and a proposed minicolumn selection algorithm are used to encode each input item into several active minicolumns. For the formation of episodic memory, a sequential memory algorithm is proposed to store the contexts between items. For retrieval of episodic memory, the local retrieval algorithm and the global retrieval algorithm are proposed to retrieve sequence information, achieving multisentence prediction and multitime step prediction. All functions of BSTM are based on bionic spiking neurons, which have biological characteristics including columnar and dendritic structures, firing and receiving spikes, and delaying transmission. To test the performance of the BSTM model, the Children's Book Test (CBT) data set was used to conduct a series of experiments under different settings, including changing the number of minicolumns, neurons and sequences, modifying sequence items, etc. Compared to other sequence memory algorithms, the experimental results show that the proposed BSTM achieves higher accuracy and better robustness.

Electrochemical corrosion and tribocorrosion behavior of CrN and CrAlN coatings in artificial seawater

AbstractThis study investigated the corrosion and tribocorrosion behavior of CrN and CrAlN coatings deposited on steel through direct current magnetron sputtering. Additionally, the effects of Al addition on the microstructure, corrosion inhibition, and tribocorrosion behavior of CrN coatings were evaluated. Compared with the CrN coating, the CrAlN coating exhibited a denser columnar crystal structure and a higher hardness of 23.8 GPa. The CrAlN coating reacted with water to form Al2O3 and Cr2O3 films, which enhanced its corrosion resistance. Moreover, the addition of Al enhanced the wear resistance of the CrN coating and reduced the material loss due to corrosion, wear, and their synergistic effects. The CrAlN coating exhibited a low corrosion current density of 1.14 × 10−8 A/cm2, indicating a 92% reduction compared with the CrN coating. Furthermore, under either open circuit potential or anodic accelerated tribocorrosion conditions, the CrAlN coating featured significantly lower total material loss and synergistic material loss than the CrN coating, demonstrating higher corrosion and tribocorrosion protection.

Strip Casting of Sm2TM17-Type Alloys for Production of the Metastable SmTM7 Phase

Conventional book casting of Sm2TM17-type alloys (where TM = Co, Fe, Cu, Zr) leads to a coarse, highly segregated microstructure, predominantly due to the slow, variable cooling rate from the mould surface towards the centre of the ingot. These cast alloys require a long homogenisation treatment to remove this segregation and develop a super-saturated, metastable SmTM7-type hexagonal phase. This SmTM7 phase is a vital precursor phase required during magnet production to develop the complex cellular structure responsible for high magnetic properties. In this work, strip casting was employed to facilitate rapid solidification to develop thin flakes (<0.5 mm thick) with a columnar grain structure. Rapid cooling has the potential to produce a homogenous microstructure consisting predominantly of the metastable SmTM7 phase. This could remove or significantly reduce the need for the energy-intensive homogenisation treatment usually required in conventional magnet manufacture. This paper investigates the effect of wheel speed (and hence cooling rate) on flake thickness, microstructure, and phase balance of the cast alloys. It was shown that for wheel speeds between 1.1 and 3.0 m/s, the microstructure showed large variation; however, in all cases, evidence of the columnar SmTM7 phase was presented. The adhesion between the melt and the wheel was deemed to be critical for the nucleation and subsequent columnar growth of SmTM7 grains, where the wheel speed controlled both the flow of the alloy onto the wheel and the thickness of the resultant flake. It was determined that in order to achieve a homogenous columnar SmTM7 structure, the maximum flake thickness should be limited to 270 μm to avoid the formation of equiaxed Sm2TM17 grains through insufficient cooling.

Suppressing formation of microcracks in laser powder bed fusion manufactured AA6061 aluminum alloy by introducing mechanical alloyed Al-25at%Ti particles

A novel approach which incorporates mechanical alloyed Al-25at%Ti particles into an AA6061 aluminum alloy powder feedstock has been used to suppress pronounced hot cracking that normally occurs in laser powder bed fusion (LPBF) manufactured AA6061 alloy. Investigation of the microstructure and tensile properties of the Ti-modified AA6061 sample fabricated by LPBF confirms the effectiveness of this approach. The suppression of microcrack formation is associated with the transition of a coarse columnar structure to fine equiaxed structure facilitated by heterogeneous nucleation of the grains on Al3Ti nanoparticles. This crack-free microstructure also results in excellent tensile properties of 252 MPa in yield strength, 361 MPa in ultimate tensile strength, and 9.7 % in elongation to fracture.

Self-Assembly Behavior, Aggregation Structure, and the Charge Carrier Transport Properties of S-Heterocyclic Annulated Perylene Diimide Derivatives.

The construction of high-performance n-type semiconductors is crucial for the advancement of organic electronics. As an attractive n-type semiconductor, molecular systems based on perylene diimide derivatives (PDIs) have been extensively investigated over recent years. Owing to the fascinating aggregated structure and high performance, S-heterocyclic annulated PDIs (SPDIs) are receiving increasing attention. However, the relationship between the structure and the electrical properties of SPDIs has not been deeply revealed, restricting the progress of PDI-based organic electronics. Here, we developed two novel SPDIs with linear and dendronized substituents in the imide position, named linear SPDI and dendronized SPDI, respectively. A series of structural and property characterizations indicated that linear SPDI formed a long-range-ordered crystalline structure based on helical supramolecular columns, while dendronized SPDI, with longer alkyl side chains, formed a 3D-ordered crystalline structure at a low temperature, which transformed into a hexagonal columnar liquid crystal structure at a high temperature. Moreover, no significant charge carrier transport signal was examined for linear SPDI, while dendronized SPDI had a charge carrier mobility of 3.5 × 10-3 cm2 V-1 s-1 and 2.1 × 10-3 cm2 V-1 s-1 in the crystalline and liquid crystalline state, respectively. These findings highlight the importance of the structure-function relationship in PDIs, and also offer useful roadmaps for the design of high-performance organic electronics for down-to-earth applications.

A Si-Nb co-alloyed AlCrN coating with good mechanical properties, excellent thermal stability and resistance to high temperature oxidation

The thermal properties of AlCrN coatings influence their application in harsh mechanical environments. This paper introduces a Si-Nb co-alloying strategy to prepare AlCrN-based coatings with good mechanical properties, excellent thermal stability and resistance to high temperature oxidation for developing high-performance tool coatings. The results indicate that, benefiting from the synergistic effect of replacing a portion of Si with an appropriate amount of Nb, Al0.59Cr0.31Si0.06Nb0.04N coating exhibits a fine columnar crystal structure different from the featureless dense structure of Al0.60Cr0.32Si0.08N coating. The different microstructure results in the difference of mechanical properties. Therefore, Al0.59Cr0.31Si0.06Nb0.04N has a higher hardness (32.3 ± 0.8 GPa) than Al0.60Cr0.32Si0.08N (28.8 ± 0.8 GPa). Meanwhile, the Al0.59Cr0.31Si0.06Nb0.04N coating get a better thermal stability and a comparable resistance to high temperature oxidation as Al0.6Cr0.32Si0.08N coating. The temperatures of thermal decomposition and oxidation resistance for Al0.59Cr0.31Si0.06Nb0.04N coating are increased by about 125 °C and 175 °C, respectively, compared with Al0.66Cr0.34N coating. In addition, the Si-Nb co-alloyed coatings maintain a better hardness after annealing.

Effect of heat treatment on toughness improvement and microstructure of Co35Cr10Ni43Ti12 medium-entropy alloy fabricated by powder plasma arc additive manufacturing

In this study, the effects of heat treatment at 1000℃ and 1100℃ on the microstructure and mechanical properties of Co35Cr10Ni43Ti12 medium-entropy alloy (MEA) were investigated, a novel MEA Co35Cr10Ni43Ti12 was fabricated by the technique of powder plasma arc additive manufacturing. The effects of the evolution of microstructure on the mechanical properties were analyzed by XRD, SEM and EBSD. Co35Cr10Ni43Ti12 MEA showed a dual-phase structure of FCC and η, and the FCC grains exhibited a typical <001> columnar crystal structure along the build direction. After heat treatment at 1000°C, the η phase was transformed from blocky to plate-like with granular, and after heat treatment at 1100°C, all of the η phase in the alloy was transformed into plate-like. For the plate-like η phase, there were 111FCC∥{0001}η and 011FCC∥[21̅1̅0]η orientation relationships with FCC, which were typical N-W orientation relationships. The printed alloy exhibited high tensile strength of 1214 MPa and low elongation of 2.8 %, and after heat treatment at 1000 °C and 1100 °C, the tensile strength of the alloys decreased to 882 MPa and 807 MPa, respectively, and the elongation increased to 10.6 % and 15.4 %.

Numerical Analysis of the Influence of a Magnetic Field on the Group Dynamics of Iron-Doped Carbon Nanotori

Columnar phases consisting of a group of carbon toroidal molecules (C120, C192, C252, C288) are studied numerically. Each nanotorus was previously doped with an iron atom. This made it possible to use an external magnetic field as a tool for influencing both an individual molecule and a linear fragment of the columnar phase. A high-precision scheme for calculating the dynamics of large molecules with a rigid frame structure is proposed to solve the problem. The group dynamics of nanotori clusters under the influence of an external magnetic field has been studied using classical molecular dynamics methods. The influence of the molecular cluster size, temperature, magnetic moment of the molecule, and magnetic field direction on the collective behavior of iron-doped toroidal molecules with different contents of carbon atoms is analyzed. Molecular dynamics calculations showed that systems of nanotori doped with a single iron atom retain a columnar structure both in the absence and in the presence of an external magnetic field. The columnar fragment behaves as a stable linear association of molecules even at sufficiently high values of magnetic induction, performing a coordinated collective orbital rotation around a common center of mass on a nanosecond time scale.