Twin Grain Research Articles

Unveiling the Structural and Chemical Evolution of Layered Oxide Cathode for Na‐Ion Batteries Induced by Water Vapor

AbstractNa‐ion batteries (NIBs) have received considerable attention as promising alternatives to lithium‐ion batteries, particularly for low‐speed electric vehicles and large‐scale energy storage applications. Currently, layered oxide compounds are considered the most important cathode materials for NIBs. However, they suffer from reduced capacity and a shortened lifespan when exposed to water vapor during storage or battery assembly. This article elaborates on the structural and chemical evolution of NaNi1/3Fe1/3Mn1/3O2 (NFM) cathode at the atomic scale in a pure water vapor environment. The Na+/H+ exchange induces the formation of a spinel‐like phase via a multi‐site nucleation mechanism. This transition preferentially occurs either at the cathode surface or along planar defects such as twin boundaries and grain boundaries. Additionally, numerous microcracks perpendicular to <003> direction appear inside NFM grains, further exacerbating the structural deterioration. Upon prolonged exposure to water vapor, NFM grains decompose into a mixture of Na2O and transition metal oxide nanoparticles (FeO, NiO, and MnO), accompanied by the generation of oxygen gas. This research provides a comprehensive atomic‐scale insight into the water vapor instability mechanism of layered oxide cathodes, offering guidance for the design and manufacture of the next generation of water vapor‐tolerant layered oxide cathodes in NIBs.

GeGra: Approaching a generic model for quantitative grain size analysis from materials microscopy data using deep learning

Grain size has a significant impact on the properties of materials, and is crucial for predicting material properties. Traditional grain size measurement relies heavily on human operators, leading to subjective results, and existing machine learning methods are typically material-specific, requiring significant labeling and training efforts for each new material. This paper provides insight into developing a deep learning-based generic grain boundary detection model (GeGra) from different material micrographs. The model is trained on 1006 images from various microscopy techniques such as light optical, Kerr, and scanning electron microscopy, acquired at different magnifications for different materials such as copper, austenite, brass, sintered hard magnet, hard metal, bronze, nickel silver, and aluminum. The developed GeGra model effectively handles visual artifacts and substructures such as twin grains, which often pose challenges for material-specific, state-of-the-art grain boundary segmentation models. The developed model achieved an IoU score of 69 % on a diverse test set and enables accurate grain size analysis using external image analysis software in less than one minute, according to ASTM standards, which is more than 5 times faster than the manual method. The developed model prioritizes generality with objective that it can have broader applicability for various materials instead of high-precision grain boundary detection. Additionally, the model has the potential to be a foundational tool for generalized grain size analysis in material microscopy, reducing the effort required for such analysis and assisting both material science experts and machine learning users.

Effects of plasma electrolytic polishing on the surface and mechanical properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si specimen fabricated by laser powder bed fusion

The high roughness of titanium alloy specimen fabricated by laser powder bed fusion (LPBF) may limit the application of LPBF technology. Plasma electrolytic polishing (PEP) can effectively reduce the surface roughness of metal samples. In this study, an orthogonal test was designed to investigate the effects of polishing time, voltage and electrolyte temperature on the reduction of roughness and wall thickness of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si specimens fabricated by LPBF. The surface roughness of the specimen decreased from Ra = 49.1 μm to Ra = 9.1 μm and the thickness decreased from 1.72 mm to 1.38 mm after the PEP. Due to the recoil pressure induced by rupture of vapor-gaseous envelope (VGE) and the annealing effect caused by electron impact, the width of α/α' grains on the surface of TC11 specimen decreased from 0.51 μm to 0.46 μm; the mean value of geometrically necessary dislocations (GND) increased by 9.8 %; the proportion of high angle grain boundaries (HAGBs) increased from 75.2 % to 80.8 %; the proportion of twin grain boundary length increased from 2.9 % to 11.9 %, and the activated twin variant type increased from 2 to 4. The number of pores in the samples reduced from 85 to 2 after PEP, which resulted in the improvement of tensile and fatigue properties. The ultimate strength and elongation of the tensile specimens increased by 6.2 % and 53.5 % respectively. The infinite fatigue life maximum stress of the high cycle fatigue specimen increased by 62.5 %. Another reason for the improvement of mechanical properties may be the self-healing of microcracks and the electroplasticity in the specimens.

Effect of hot rolling and annealing on microstructure, crystallographic texture, and mechanical properties of Fe11.5 Co20.6 Ni40.7 Cr12.2 Al7.8 Ti7.2 high entropy alloy

The evolution of microstructure and texture during the thermomechanical processing of a Fe-Co-Ni-Cr-Al-Ti dual phase high entropy alloy consists of L12 (γ′) ordered precipitates in the disordered FCC (γ) matrix and its effect on the mechanical properties was investigated. The as-cast alloy was annealed at 1100 °C after 25 % and 50 % hot rolling reduction. The grain size becomes finer, and a considerable amount of annealing twin boundaries (Ʃ3 boundaries) developed in the hot rolling and annealed (HRA) samples. The α-fiber (ND||<110>) texture and twin-related texture components increase after HRA treatment. The mechanical response at room temperature is evaluated employing hardness and uniaxial tensile tests. A significant reduction in hardness, from 448 ± 6 HV to 381 ± 12 HV, is observed in the 50 % hot rolled annealed sample compared to the as-cast sample. Additionally, the yield strength reduced from 779 to 595 MPa with an increment in the ductility from 12.5 to 17.2 % in the as-cast and HR50A samples, respectively. Finally, it has been demonstrated that the increase in coherent twin boundaries and grain size excluding twin boundaries, led to the observed mechanical behavior.

Effects of the Primary Carbide Distribution on the Evolution of the Grain Boundary Character Distribution in a Nickel-Based Alloy

Grain boundary engineering (GBE) was carried out on a nickel-based alloy (GH3535, Ni-16Mo-7Cr-4Fe), which intrinsically has many strings of primary molybdenum carbides. The strings induce inhomogeneous grain size distributions and increase the difficulties in achieving a GBE microstructure. In this work, the effects of the primary carbide distribution on the grain boundary network (GBN) evolution were investigated. A higher proportion of Σ3n grain boundaries (GBs) associated with extensive multiple twinning events was achieved in the specimen with more dispersive and finer primary carbides, which are the results of cross-rolling, i.e., cold rolling with a changed direction. In a starting microstructure with many strings of primary carbides, the dense and frequent occurrence of particle-stimulated nucleation (PSN) around the carbides induced more general high-angle GBs into the GBN, and the inhibition of GB migrations by the carbide strings suppressed the formation of large-sized highly twinned grain clusters. As a consequence, the Σ3n GBs could not be effectively enhanced.

Study on microstructure evolution and deformation behavior of Mg– Zn base alloy pipes during hot bending

The strong basal fiber texture of magnesium (Mg) alloy pipes usually leads to poor secondary forming performance. In this study, Mg–2Zn-0.4Ce-0.4Mn (ZME) and Mg–2Zn-0.4Ce-0.4Mn-0.2Ca (ZMEX) pipes were prepared. Compared with the ZME pipe, the ZMEX pipe with a weaker initial texture exhibits excellent bending performance, with a peak load displacement (PLD) of 14.5 ± 0.5 mm and a total energy absorption (TEA) of 142.9 ± 1.7 J. The difference in bending performance between the two pipes is related to the deformation mechanism during hot bending. In the hardening stage, the deformation of the compression zone (CZ) of the two pipes is mainly ETW nucleation, and the overall proportion of twin grains is similar. However, in the tensile zone (TZ), the deformation of the ZME pipe is mainly prismatic slip, while the weak initial texture of the ZMEX pipe leads to the deformation dominated by both prismatic and multiple pyramidal slips, resulting in a higher hardening rate. In the softening stage, the deformation behavior in the CZ and TZ of both pipes tends to be similar. In addition, it is revealed that the softening phenomenon of both pipes after the bending displacement reaches PLD is caused by discontinuous dynamic recrystallization (DDRX) driven by high-density dislocations accumulated in the later CZ and TZ. The research on the microstructure evolution and deformation mechanism of Mg alloy pipe during bending deformation carried out in this study is of great significance for optimizing its secondary forming controllability and further expanding its application.

Influence of corrugated/flat rolling on microstructure and tensile property of coarse-grained AZ31–0.25Ca cast alloy

Novel corrugated rolling technology (CR) and conventional flat rolling (FR) were employed for rolling the AZ31–0.25Ca cast alloy without prior predeformation. The impact of corrugated rolling and/or flat rolling on texture modification, microstructure evolution, and mechanical properties of the magnesium alloy during two-pass rolling was examined using optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), tensile tests at ambient temperature, and ABAQUS finite element simulation analysis. The results indicate that the AZ31–0.25Ca cast alloy, after homogenization with a coarse grain structure of ∼200 μm, can endure significant plastic deformation with a 60 % total rolling reduction in both corrugated-flat rolling (CFR) and flat-flat rolling (FFR) without experiencing edge cracking. Twinning is activated dramatically except for dislocation slip during CFR, which induced high-density dislocations piling up at the twin boundaries and grain boundaries of α-Mg grains. The CFR sheet exhibited a macroheterogeneous structure attributed to the distinctive corrugated roll profile. Elevated shear strain and intensified frictional shear stress were observed at the trough, resulting in the formation of an asymmetric cross shear band in the CFR sheet. Denser deformation twins and finer recrystallized grains are present at the trough, whereas fewer and coarser ones are observed at the peak, while there is a significant texture weakening effect for corrugated rolling in contrast to the conventional flat rolling. but the stress and strain heterogeneity and asymmetric cross shear band also induce strong stress concentration and result in a premature cleavage fracture and a lower tensile property in CFR sheet compared to that of the FFR sheet.

Enhanced mechanical properties of boron carbide ceramics prepared by spark plasma sintering with boron nitride nanosheets addition

Boron carbide (B4C) ceramics with enhanced mechanical properties have been fabricated with boron nitride nanosheets (BNNSs, 1.5–5 wt%) as reinforcement via spark plasma sintering. The densification temperature of the B4C ceramic containing 3 wt% BNNSs (B4C-3 %BNNSs) was reduced to 1480–1700 °C, approximately 100 ℃ lower than the pure B4C ceramic. The B4C-3 %BNNSs composites with a density of 98.9 % and associated Vickers hardness of 34.4 GPa, flexural strength of 654 MPa, and fracture toughness of 4.86 MPa·m1/2 that represent a respective increased by 1.1 GPa (3.3 %), 178 MPa (37.4 %) and 1.57 MPa·m1/2 (47.7 %) relative to pure B4C. The reinforcement mechanisms due to BNNSs combined with B4C involves a synergistic effect of the decrease in densification temperature where the BNNSs promote B4C grain rearrangement, B4C twin grain boundaries, and BNNSs pull-out, crack branching and crack deflection effects.

Intrinsic Grain Boundary Structure and Enhanced Defect States in Air-Sensitive Polycrystalline 1T'-WTe2 Monolayer.

Monolayer WTe2 has attracted significant attention for its unconventional superconductivity and topological edge states. However, its air sensitivity poses challenges for studying intrinsic defect structures. This study addresses this issue using a custom-built inert gas interconnected system, and investigate the intrinsic grain boundary (GB) structures of monolayer polycrystalline 1T' WTe2 grown by nucleation-controlled chemical vapor deposition (CVD) method. These findings reveal that GBs in this system are predominantly governed by W-Te rhombi with saturated coordination, resulting in three specific GB prototypes without dislocation cores. The GBs exhibit anisotropic orientations influenced by kinks formed from these fundamental units, which in turn affect the distribution of grains in various shapes within polycrystalline flakes. Scanning tunneling microscopy/spectroscopy (STM/S) analysis further reveals metallic states along the intrinsic 120° twin grain boundary (TGB), consistent with computed band structures. This systematic exploration of GBs in air-sensitive 1T' WTe2 monolayers provides valuable insights into emerging GB-related phenomena.

Origins of twin boundaries in additive manufactured stainless steels

316L and 304L stainless steels and a compositional gradient of both are fabricated using the same processing parameters via laser directed energy deposition additive manufacturing. In those alloys, the increase in chromium-to-nickel ratio is accompanied with grain refinement and formation of a high density of twin boundaries, i.e. Σ3 boundaries. By means of electron microscopy, crystallographic and thermodynamic calculations, we demonstrate that two mechanisms arising from the ferrite-to-austenite solidification mode are at the origin of twin boundary formation and grain refinement: (1) inter-variant boundaries emerging from the encounter of pairs of austenite grains formed from a common ferrite orientation with Kurdjumov–Sachs orientation relationship; (2) icosahedral short-range-ordering-induced (ISRO) nucleation of twin-related γ grains directly from the solidifying liquid. These findings define new routes to achieve grain boundary engineering in a single step in FeCrNi alloys, by tailoring the solidification pathway during the AM process, enabling the design of functionally graded materials with site-specific properties.

Grain boundary junction disclinations in nanoparticles

Grain boundary junction (GBJ) disclinations are ubiquitous at the nanoscale in icosahedra and decahedra. These structural motifs consist of several tetrahedra sharing a twin grain boundary. According to the coincident site lattice (CSL) theory this twin grain boundary is referred to as Σ3<110>{111} grain boundary. In the present work, GBJ disclinations involving a low energy grain boundary Σ11<110>{113} are reported. Σ3−Σ3−Σ11 triple junction disclination is energetically preferred at the nanoscale as opposed to the ideal (without any misorientation mismatch) Σ3−Σ3−Σ9 triple junction. Molecular dynamics simulations are employed to study the disclinations in three dynamical processes key for nanoparticle synthesis − growth, coalescence, and solidification; across three metal systems Ag, Cu, and Pt which cover a range of stacking fault energies. Results indicate that Pt has a higher preference for disclinations while they are almost non-existent in Cu and to a lesser degree in Ag. Several types of disclinations have been identified and catalogued. Gaussian images (used as a proxy for simulating scanning transmission electron microscopy high angle annular dark field images) reveal that some of the disclinations induce artifacts which makes it non-trivial to identify them even when they are present in experimental particles. A key characteristic of the GBJ disclinations is the rapid change in misorientation angle around Σ11 grain boundary with distance away from the disclination. In this scenario, there is a need to reassess the methodology currently in use for identification of grain boundary type at the nanoscale.

Microstructural response characteristics of SAC305/Cu column joint under friction embedded welding conditions

The friction welding method for macro-scale weldments was introduced into the manufacturing of electronic products. Without mold assistance, the positioning and connection of micro copper columns in column grid array packaging (CGA) devices were achieved. The average connection strength of 40.6 N and the intermetallic compound interface layer meant that effective connections were achieved. In the poorly identified stirring-mixing zone (SMZ) in scanning electron microscopy (SEM) images, electron backscatter diffraction (EBSD) results showed that this region was composed of recrystallized grains, twin grains, and Ag3Sn and Cu6Sn5 particles distributed inside or at the grain boundaries. The grain size was about 2 μm, and the Ag3Sn and Cu6Sn5 particle sizes were broken to 250 nm and 120 nm due to stirring. The SMZ at the bottom of the copper column only underwent deformation-induced dynamic recrystallization, while the SMZ on the side was discharged from the bottom of the copper column, so it underwent dynamic recrystallization through the process of cutting crushing-extruding and flow-bonding-deformation. Therefore, the hardness of SMZ was significantly reduced after welding. Unlike traditional friction welding, in the thermo-mechanical affected zone (TMAZ), the solder not only underwent deformation but also formed 47.8% recrystallization microstructure and 14.6% recovery microstructure. Therefore, the effect of deformation strengthening was weakened and recrystallization led to a decrease in hardness. Recovery was the main response behavior in the micro-deformation zone (MDZ). Combined with the numerical simulation results, the temperature and stress driving conditions of the microstructure of each micro-region in instantaneous friction embedded welding (FEW) were also discussed.

The role of embedded coordinates for disclinations and disconnection components

The standard model is applied for partial disclination pairs in hard materials. These defects comprise two partial disclinations and an intervening fault that can be a twin boundary, grain boundary or interphase boundary. In three dimensions there are six types. Two of them can be considered Somigliana disclinations. The standard model includes geometrically nonlinear embedded coordinates. It entails partitioning of displacements that result in configurations and strain fields not considered classically for partial disclinations. These concepts are applied to boundary junctions, disconnections, and multiple twins. Recovered stress-free structures are considered.

Mechanism of high temperature mechanical properties enhancement of Ni-based superalloys repaired by laser directed energy deposition: Microstructure analysis and crystal plasticity simulation

The high-temperature tensile and fatigue performance play a crucial role in the applications of repaired Ni-based superalloys by Laser directed energy deposition (LDED). This work investigates the effect of microstructure on the high temperature (650 °C) mechanical behaviors of GH4169 superalloys repaired by LDED with the microstructure characterizations and crystal plasticity modelling. Results indicate that the solution and aging heat treatment (STA) is necessary to homogenize the distributions of precipitations. Microstructure characterizations and crystal plasticity modelling imply that the plasticity deformations occur mainly in columnar dendrites of fusion area and twin grains of substrate, which enhance the tensile strength and elongation rate of repaired area and demonstrates comparable characteristics with the casting alloy. At the same time, the existence of the Laves phase and carbide cannot eliminate the dynamic strain aging phenomenon of repaired material. Similarly, under high stress levels (850– 950 MPa), the fatigue performance of repaired material is primarily influenced by the plastic deformation and exhibits similarity to that of the substrate; however, under low stress levels (650– 750 MPa), it is primarily influenced by the presence of defects, resulting in an obviously longer fatigue life for the substrate.

Origin of nucleation and growth of extension twins in grains unsuitably oriented for twinning during deformation of Mg-1%Al

A large number of anomalous extension twins, with low or even negative twinning Schmid factors, were found to nucleate and grow in a strongly textured Mg-1Al alloy during tensile deformation along the extruded direction. The deformation mechanisms responsible for this behaviour were investigated through in-situ electron back-scattered diffraction, grain reference orientation deviation, and slip trace-modified lattice rotation. It was found that anomalous extension twins nucleated mainly at the onset of plastic deformation at or near grain boundary triple junctions. They were associated with the severe strain incompatibility between neighbour grains as a result from the different <a> basal slip-induced lattice rotations. Moreover, the anomalous twins were able to grow with the applied strain due to the continuous activation of <a> basal slip in different neighbour grains, which enhanced the strain incompatibility. These results reveal the complexity of the deformation mechanisms in Mg alloys at the local level when deformed along hard orientations.

Thermal deformation behavior and microstructure analysis of the as-cast super austenitic stainless steel Sanicro35

Thermal compression experiments on the super austenitic stainless steel Sanicro35 were carried out using a Gleeble 3800 thermal simulation laboratory machine to investigate its thermal deformation behavior at different deformation temperatures (900 °C–1150 °C) and strain rates (0.001–10 s−1). The microstructure of the large deformation zone of the specimen was investigated using electron backscatter diffraction (EBSD). The results show that the thermal compression rheological stress of the super austenitic stainless steel Sanicro35 decreases with increasing temperature and decreasing strain rate. Dynamic recrystallization (DRX) is the main softening mechanism for this material. The morphology characteristics, recrystallization fraction, dislocation density and twin grain boundary distribution of the microstructure were analyzed by EBSD. With the increase of deformation temperature, the higher grain boundary mobility contributed to the growing of DRX grains. As the strain rate increases, the larger deformation storage energy provides sufficient activation energy for DRX grain nucleation, and the nucleation of DRX grains becomes denser. The twin boundaries are mainly distributed within the DRX grains. The smaller the grain size of DRX, the denser the nucleation of twin boundaries, and the generation of twins can promote the development of DRX. The softening mechanism under most deformation conditions is discontinuous dynamic recrystallization (DDRX). However, at 10 s−1, the high strain rate causes microbands to be generated within the deformed grains, and the microband boundaries evolve toward the high-angle grain boundaries (HAGBs) with increasing temperature, which promotes the occurrence of Continuous dynamic recrystallization (CDRX).

Twin spacing and grain size dependent tensile deformation mechanism of a nano-ploycrystalline Ni-based alloy

It is easy to form twins in Ni-based wrought superalloys with low stacking fault energy, but the effect of grain size and twin spacing on mechanical properties in nano-ploycrystalline Ni-based alloys is rarely studied. Based on the composition of a novel Ni-based wrought superalloy, molecular dynamics simulations were used to study the effect of grain size and twin spacing on the deformation behavior of the Ni57Cr19Co19Al5 alloy. The results show that the elastic modulus and tensile strength of the nano-polycrystalline Ni57Cr19Co19Al5 alloy exhibit clear grain size dependence. As the grain size exceeded 16 nm, the elastic modulus remained unchanged. The tensile strength and grain size satisfy the Hall–Petch relationship, and the dislocation motion dominates the plastic deformation. For the grain size below 16 nm, the elastic modulus decreases as the grain size decreases. The tensile strength and the grain size exhibit an inverse Hall–Petch relationship. The grain boundary sliding and grain torsion mechanisms dominated plastic deformation in the nano-polycrystalline Ni57Cr19Co19Al5 alloy without twin. In the nano-polycrystalline Ni57Cr19Co19Al5 alloy containing twins, the twin boundaries inhibited the torsion of grains, and grain boundary sliding dominated plastic deformation.

Deformation and boundary motion analysis of a faceted twin grain boundary

In this article, molecular dynamics simulations are used to understand how a nickel bicrystal with faceted incoherent Σ3 grain boundaries responds to uniaxial tensile loading. The deformation response is studied over a wide range of temperatures (100 – 900 K) and strain rates (107 – 1010 s−1). The dislocation extraction algorithm and common neighbor analysis are employed to identify the deformation mechanisms. Our results reveal that the yield stress decreases with temperature and increases with strain rate; whereas the elastic modulus decreases with temperature and is independent of strain rate. Furthermore, incipient plasticity is detected ahead of the yield point at lower temperatures and lower strain rates. Interestingly, the incoherent twin grain boundaries are quite mobile under the uniaxial tensile loading at lower temperatures and lower strain rates. But this mobility decreased at higher temperatures and higher strain rates, thereby, confirming this faceted grain boundary's non-Arrhenius (anti-thermal) migration behavior even under mechanical loading. From a deformation perspective, the incoherent twin facet of the grain boundary served as the major source for stacking fault formation at lower temperatures and higher strain rates. However, with the increase in temperature, the stacking faults became shorter and originated from both the incoherent twin facet and the tips of coherent twin facet. These results are in qualitative agreement with the experimental results documented in the literature.

Characterization of Kinetics-Controlled Morphologies in the Growth of Silver Crystals from a Primary Lead Melt

Silver, a precious metal, can be recovered as a by-product of the processing of non-ferrous metals such as lead. In this work, silver crystals grown from the controlled cooling of a 10% silver–90% lead melt have been examined to quantify crystal morphologies developed under industrial conditions. X-ray tomography (XCT) is adapted to quantify the size and morphology of silver crystal structures grown from the Ag-Pb melt. The examination utilized high X-ray energies and small sample sizes to mitigate attenuation and enhance image quality. Examination of single crystal dendrites under high magnification demonstrates that silver crystals, even those grown under commercial conditions, yield a Face-Centered Cubic (FCC) crystalline lattice, which could be important for the practical extension of this work to the commercial production of Ag nano-crystals and crystalline supra-molecular structures. The crystals observed are composed of multiple twinned euhedral grains in a variety of dendritic to acicular arrangements, yielding a substantial heterogeneity of crystalline forms. XCT data were used to generate size and shape descriptors for the individual crystals. The results were compared to an equivalent set of descriptors generated from laser sizing examination of a sample of unconsolidated crystals from the same experimental run. The correspondence to within 9% of the crystal equivalent diameters determined independently by the XCT and laser sizing demonstrates a favorable outcome in particle sizing as achieved by visual inspection of XCT results. XCT examination of crystal assemblages identifies small octahedral crystals and larger triangular platelets. The structures expected for FCC crystals grown at thermodynamically controlled conditions are not observed in our systems, suggesting the possibility of the first crystal nuclei form at such conditions, but their growth transition to kinetically controlled mechanisms occurs as their size increases above a threshold cutoff. Based on literature observations, this size threshold is much smaller than the resolution of the XCT instrumentation employed herein. Our characterization data are in fact consistent with thermodynamics/kinetics—and then kinetics-controlled mechanisms—as the crystal size increases. This observation is important because the systems considered here are representative of commercial processes. As such, this work extends prior crystal growth concepts, which were explored in aqueous systems often probed by electrodeposition.

Developing austenitic high-manganese high-carbon steels for biodegradable stent applications: Microstructural and mechanical studies

Fully degradable stents that temporarily support healing tissue can solve potential long-term complications associated with permanent implants. In this study, we investigate austenitic high-manganese high-carbon steels as promising candidates for such biodegradable stent applications. The microstructural characteristics and mechanical properties of the Fe–Mn–C steels were systematically analysed to assess their suitability for this purpose. A series of four austenitic Fe–Mn–C steels with varying manganese (15 and 30 wt%) and carbon (0.6–1.0 wt%) content were processed by vacuum induction casting, annealing and hot forging. Microstructural analysis was performed, and the hot forged materials were further evaluated using ultrasound, macro hardness, and (stopped) quasi-static tensile tests to assess stent-related parameters. In contrast to the as-cast state, the hot forged steels exhibited high chemical homogeneity, as was found by energy-dispersive X-ray spectroscopy (EDXS). Electron backscatter diffraction (EBSD) revealed comparability between the four steels regarding their annealing twin fractions and grain size distributions. An austenitic microstructure was revealed for all modifications by transmission X-ray diffraction (XRD), except Fe–15Mn–0.6C, which displayed a minor ε–martensite fraction. Reducing manganese from 30 to 15 wt% resulted in favourable effects, including a higher Young's modulus, lowered offset yield strength, and an increased ultimate tensile strength due to larger strain hardening while preserving a high total elongation. However, reducing the carbon content to 0.6 wt% diminished the mechanical performance due to reduced solid solution strengthening and the ε–martensite formation. Among the investigated steels, the novel Fe–15Mn–0.8C alloy exhibited the most attractive combination of the studied properties for potential stent applications.