Dislocation Accumulation Research Articles

Crystallographic texture and multiscale boundaries mediated creep anisotropy in additively manufactured Ni-based Hastelloy C276 superalloy

The microstructure and high-temperature creep mechanisms of Ni-based Hastelloy C276 superalloy fabricated using wire and arc-based directed energy deposition were investigated systematically and innovatively. The microstructural investigation revealed that the as-fabricated samples comprise γ-Ni matrix and topologically close-packed (TCP) P phase precipitates. The γ matrix subgrains and grains are spread over multiple highly textured columnar dendrites, with a majority of γ <001> crystallographic orientations closely aligned along the deposition direction. Moreover, the interdendritic regions exhibit severe Mo segregation, P phase particles, and dislocation bands. Creep tests were conducted on miniature samples under various temperature and stress conditions, loaded either in the deposition direction (DD) or travel direction (TD). DD samples exhibit lower minimum strain rates, greater strains-to-failure, and longer creep rupture lifetimes than TD samples, indicating significant creep anisotropy. Dislocation creep was identified as the primary creep mechanism for both DD and TD conditions. During creep, dynamic precipitation of TCP phases occurred in the interdendritic regions, resulting in varying creep resistance between interdendritic and dendritic core regions. Isostress and isostrain models, considering both crystallographic texture and precipitation strengthening, reasonably predicted the observed creep anisotropy during the secondary creep stage. Additionally, variations in the Schmid factor led to significant deformation incompatibility among dendrites in TD samples. Dislocation accumulation in TD sample interdendritic regions promoted new grain nucleation, triggering dynamic recrystallisation, facilitating grain boundary sliding, and accelerating tertiary creep. Furthermore, TCP phase particles in the interdendritic regions contributed to microcrack development, further accelerating creep fracture, especially in the TD condition.

Comparison of Dislocation Accumulation Behavior upon Thermal Cycling in Ti–30Ni–20Cu and Ti–39Ni–11Pd Shape Memory Alloys

Comparison of Dislocation Accumulation Behavior upon Thermal Cycling in Ti–30Ni–20Cu and Ti–39Ni–11Pd Shape Memory Alloys

Elucidating the dual effect of vanadium microalloying on hot deformation behavior of high nitrogen martensitic stainless steel

Precipitates always have a complex effect on the hot work hardening and recrystallization softening of materials. In this work, the dual effect of V-microalloying on hot deformation behavior and microstructure evolution of high nitrogen martensitic stainless steel (HNMSS) was investigated by hot compression experiments, modeling study and microstructure characterization. The results showed that V-microalloying enhanced the flow stresses and activation energy of 0.2V steel due to the fine grain strengthening effect and the blocking effect of dynamic precipitation on dislocation movement and grain boundary migration. On the other hand, the recrystallization model and deformed microstructure indicated the more intense dynamic recrystallization (DRX) softening effect in 0.2V steel, inducing the faster decrease of flow stress after the peak stress. V-microalloying promoted the dynamic precipitation of HNMSS during hot deformation, which reduced the size and increased the number of precipitates in 0.2V steel. The fine precipitates hindered dislocation movement, promoted dislocation accumulation and entanglement, formed a particle deformation zone (PDZ) with high dislocation density and large orientation gradient, and then induced the occurrence of particle-stimulated nucleation (PSN). In addition, the dislocation cells evolved from dislocation entanglement were also favorable nucleation sites for DRX.

Creep performance in a CoNi-based single crystal superalloy with super-high γ′ volume fraction at 760 °C and equivalent high stress

The creep performance at low temperature and high stress is one crucial property for the single crystal superalloys widely used for turbine blades. In this study, the creep behavior of a CoNi-based single crystal superalloy with super-high γ′ volume fraction (Vγ′ = ∼90%) was investigated at 760 °C/550 MPa based on microstructural (γ and γ′ phases) and deformation substructural (dislocations, anti-phase boundaries (APBs) and stacking faults (SFs)) analyses to reveal its creep mechanism under low temperature/high stress conditions. The super-high Vγ′ contributes to the rapid transformation of creep mechanisms from the matrix dislocation movement in the initial decelerating stage to the APB-coupled dislocation pairs and their evolving non-planar SF ribbons inside γʹ precipitates during the accelerating stage. In the following second decelerating stage, the interactions between SFs and APBs improve the deformation resistance of γ′ precipitates and decrease the creep rate. Subsequently, the high density of APBs is believed to play a significant role in microstructural stability and promotes the accumulation of matrix dislocations, which is responsible for the steady and final accelerating stages. Appropriate Vγ′ and increasing the APB energy are assumed to improve the creep resistance of CoNi-based single crystal superalloys by enhancing the strengthening effect of dislocation accumulation in γ matrix and critical shear stress of γ′ phase.

Effect of cryorolling on microstructure evolution and mechanical properties of spray deposited Cu-Fe alloy

In order to solve or suppress the problem of macro segregation of Fe phase of Cu-Fe alloy in the traditional casting process, we successfully prepared Cu-10Fe alloy prefabricated slabs with homogeneous and fine microstructure by spray deposition and achieved high strength Cu-10Fe alloy thin strips by subsequent cryorolling. Cryorolling was carried out at different reductions to investigate the relationship between microstructure evolution and mechanical properties. The results show that the spray deposited alloys have good plasticity and low temperature workability. As the reduction increased, the Fe phase becomes more fibrous and the average grain size of the alloy is refined to 0.35 μm. The {112}<111> texture was gradually transformed into a stabilized {110}<112> texture during cryorolling suggested that the low temperature suppressed cross-slip and improved the strength of the alloy. The mechanical properties of the alloys improved significantly after cryorolling is mainly attributed to the significant grain refinement, dislocation accumulation and the presence of ultrafine grains during the cryorolling process. The successful development of thin strips of Cu-Fe alloy with uniform distribution of Fe phase and high strength provides a new idea for the preparation of thin strips of immiscible alloys such as Cu-Fe alloy.

Excellent ductility of an austenitic stainless steel at a high strength level achieved by a simple process

In the pursuit of simultaneously improving the yield strength and plasticity of austenitic stainless steel, a new austenitic stainless steel was fabricated by induction smelting using a pure N2 atmosphere, hot forging, cryogenic rolling, and annealing. The material was characterized by microstructures with 3–4 μm uniform finer grains, fine precipitates, high thermal stability austenite, and extensive high-angle grain boundaries. The elongation after fracture, yield strength, and ultimate tensile strength of the samples reached 53.5 %, 707 MPa, and 1020 MPa, respectively, as well as 61 %, 600 MPa, and 977 MPa, respectively, at the same time. Moreover, a high strain hardening rate was achieved in the new stainless steel. The appropriate uniform finer grains not only played a role in grain-refined strengthening but also provided intragranular spaces and sufficient mean free available paths for dislocation accumulation and movement. Precipitates, which were coherent or semi-coherent with the matrix, provided interfaces for dislocation accumulation and obstructions for dislocation movement. Extensive high-angle grain boundaries with appropriate finer grains served as another important factor for excellent ductility due to the inhabitation and resulting deviation of crack propagation. In addition, strain-induced mechanical twinning in the current austenitic stainless steel contributed to excellent ductility and high strength.

Investigation of tensile deformation behavior of pure titanium at 20 K

The cryogenic tensile properties and deformation behaviors of pure titanium at liquid hydrogen temperature (20 K) were investigated. Compared with 298 K, high ultimate tensile strength (UTS) of 978 MPa and the excellent elongation-to-fracture (El) of 48 % were achieved. A large number of {101‾2}<1‾011 > and {112‾2}<112‾3‾ > deformation twins released local stress concentration and lead to high work hardening rate, which endow pure titanium with excellent strength and ductility. In addition, the inhibition of multiple necking of pure titanium at 20 K is due to a large number of deformation twins released the stress concentration and produced a strong dynamic hardening effect, which relieved the local plastic deformation. And the serrated stress-strain curve is caused by intermittent activation of twining and dislocation slip. Finally, the twins are thinner at 20 K are attributed to the more obvious stress concentration. The cryogenic deformation mechanism and fracture behavior are explained from two aspects of dislocation accumulation and thermal physics.

Hot Deformation Behavior and Microstructure Evolution of Al-7.92 Zn-1.64 Mg-2.00 Cu Alloy

During the thermal deformation of aluminum alloy materials, the deformation conditions such as deformation volume, temperature and strain rate are important factors that influence the deformation mechanisms such as work hardening, dynamic recovery and dynamic recrystallization. Under the interaction of different deformation mechanisms, the properties of aluminum alloy materials will change significantly. In this study, isothermal hot compression experiments were conducted on the Al-7.92 Zn-1.64 Mg-2.00 Cu alloy to analyze its hot flow behavior (T = 250~450 °C, ɛ̇ = 0.001~1 s−1). The obtained flow behavior data were used to construct an Arrhenius-type constitutive equation and processing maps, investigating organizational evolution under diverse hot deformation conditions. The results show that the energy dissipation rate can reach 0.37 when the deformation temperature T = 380~450 °C and the strain rate ɛ̇ &lt; 0.1 s−1, suggesting that the material is most suitable for thermal deformation processing at high temperatures and low strain rates. At a strain rate of 0.1 s−1 and a temperature of 450 °C, the percentage of recrystallized grains and substructures increased by 7.20% and 3.14%, respectively, compared to 300 °C, which is due to the severe dynamic recovery and dynamic recrystallization. At 350 °C and 0.1 s−1, there was a higher percentage of recrystallized grains and substructures, 5.44% and 5.87% higher, respectively, than at a strain rate of 1 s−1, indicating that the release of dislocation accumulation due to deformation storage energy will be more favored at low strain rates, which promotes the enhancement of the dynamic recrystallization mechanism.

An atomistic study on the HELP mechanism of hydrogen embrittlement in pure metal Fe

The Hydrogen Enhanced Localized Plasticity (HELP) mechanism is one of the most important theories explaining Hydrogen Embrittlement in metallic materials. While much research has focused on hydrogen's impact on dislocation core structure and dislocation mobility, its effect on local dislocation density and plasticity remains less explored. This study examines both aspects using two distinct atomistic simulations: one for a single edge dislocation under shear and another for a bulk model under cyclic loading, both across varying hydrogen concentrations. We find that hydrogen stabilizes the edge dislocation and exhibits a dual impact on dislocation mobility. Specifically, mobility increases below a shear load of 900 MPa but progressively decreases above this threshold. Furthermore, dislocation accumulation is notably suppressed at around 1 % hydrogen concentration. These findings offer key insights for future research on Hydrogen Embrittlement, particularly in fatigue scenarios.

Study on Creep Anisotropy at 760°C of a Single Crystal Superalloy

In this paper, the creep properties of a second generation single crystal superalloy DD412 with [001], [011] and [111] orientation at 760°C were studied. The experimental results show that the creep properties of DD412 alloy with different orientations have significant anisotropy under the stress of 580MPa-620MPa at 760°C. The [001] and [111] oriented alloys have remarkably better creep performance than [011] oriented alloy. And the creep performance of [111] oriented alloy is superior to that of [001] oriented alloy under the condition of 760°C/620MPa, while the tendency is inverse under the condition of 760°C/580MPa. The dislocation configurations of the alloy with different orientations during creep process are significantly different, resulting in creep anisotropy. For [001] and [111] oriented alloy, there are large number of dislocations in the γ channel that intersect and form local high-density dislocation aggregation, which has a strong blocking effect on the movement of dislocations. For [011] oriented alloy, the <110>{111} dislocations intersect each other to form <112>{111} partial dislocations and stacking faults, cutting into the γ′ phase, which lead to rapid growth of creep deformation and the poor creep performance of [011] oriented alloy.

Migration of grain boundary triple junctions in nanocrystalline metals initiated by accumulated dislocations

The evolution of grain boundary (GB) networks in polycrystalline metals depends not only on the movement of the constituent GBs but also on the migration of GB triple junctions (TJs), the latter would have strong influence on the mechanical properties of polycrystals. We investigate the migration mechanism of TJs in face-centered cubic metals using molecular dynamics simulations. The TJ migration is revealed to follow a typical stick-slip behaviour that involves TJ grooving and coordinated GB migration. Upon external shear loading, the TJ experiences a quick migration process, resulting in a grooved TJ configuration with curved GBs at the TJ. The accumulation of dislocations at the TJ facilitates the TJ grooving process, since it compensates the angle gap caused by the inconsistent shear-migration coupling factors between the GBs. After reaching a critical grooving depth, the TJ migration is stagnated, while the connecting GBs begin to migrate via disconnections emitted from the TJ. Based on the mechanism of accumulated dislocation-initiated TJ migration, we propose an energetic model that considers the extra energy barrier for the accumulation of dislocations, to quantify the effect of GB misorientation on TJ migration. These findings deepen our understanding of the physical origin of TJ migration and point out the importance of dislocation accumulation on coordinated GB motion in nanocrystalline metals.

Amorphization of Gd2Zr2O7 induced by mechanical deformation in nanoindentation

Amorphization has become an important plastic deformation mechanism for covalently-bonded ceramics, which can disturb their crystalline order and affect their mechanical behaviors. Unlike the covalently-bonded ceramics, however, amorphization induced by mechanical deformation is rarely observed in ionically-bonded ceramics. In this work, we show direct experimental evidence that nano-scale amorphous zones in Gadolinium Zirconate ceramic are the ultimate stage of plasticity and relate to an accumulation of dislocations. In addition, the occurrence of amorphization also causes the unusual indentation size effect.

Investigating the Distribution Pattern of Threading Edge Dislocation Low Angle Grain Boundaries in 4H-SiC Wafers Using Synchrotron X-Ray Topography

Silicon carbide (SiC) has emerged as a significant wide bandgap semiconducting material, playing a pivotal role in the fabrication of high-frequency, high-power electronic devices in modern times. Its exceptional properties, such as high thermal conductivity, high saturation velocity, and high breakdown field, have positioned it as a valuable constituent in various application fields, including transportation, communication, and bioelectronics. However, the efficacy and long-term reliability of SiC-based devices are critically dependent on the quality of both the SiC substrate and epitaxial material employed. The presence of deleterious defects within these materials can induce device degradation and failure, posing a significant challenge in realizing the full potential of the device. Therefore, it is imperative to address the quality while maintaining the availability of large-scale single crystals of SiC to further expand the development of SiC-based device technology. Among various kinds of crystallographic defects in bulk crystal, low angle grain boundary (LAGB) is a commonly observed planar defect that prevents the implementation of large size (≥ 1 cm2) SiC devices [1]. In both 6H and 4H-SiC, LAGBs have been observed to replicate during the epitaxial growth [2], which can lead to profound impact on the physical and electronic properties of the crystal that subsequently triggers device degradation. Literature reveals that the presence of LAGBs in commercial wafers can lead to increased leakage currents during reverse-bias operation of devices [3]. Besides, the existence of prismatic tilt boundaries is usually accompanied with aggregation of edge type basal plane dislocations (BPDs) [4], which cause severe degradation in SiC bipolar devices [5] as BPD segments can dissociate into partials and form stacking faults in between [6].This study investigated a unique distribution pattern of LAGBs observed on physical vapor transport (PVT) grown off-axis 4H-SiC wafers. Synchrotron X-ray topographs in both transmission and grazing geometry reveal that three sets of LAGBs are presented on one side of the wafer, away from the facet position, each set contains numerous LAGB arrays. Figure 1 (a) shows a schematic diagram where each oval outlines the approximate location of each LAGB set. As the grazing-incidence topographs shown in Figure 1 (b), the LAGB sets distributed at the upper and lower region of the wafer consist of white contrast threading edge dislocations (TEDs) extending from the inner area towards the edge approximately along 60º and 120º direction, respectively. The LAGB set positioned at the middle region of the wafer consists of dark contrast TEDs extending from the inner area towards the edge approximately along 90º direction. All individual TED arrays in each LAGB set extends along the <1-100> directions, with identical Burgers vectors perpendicular to the array direction. The white and dark contrast of TEDs corresponds to tilt in opposite directions. White contrast TEDs are with Burgers vectors of 1/3[2-1-10] and 1/3[1-210], dark contrast TEDs are with Burgers vectors of 1/3[-2110] and 1/3[-12-10]. Such TED LAGBs are identified as pure tilt boundaries that accommodate the rotational misorientation between two adjacent regions. Therefore, a flat wafer is expected to exhibit zero net misorientation due to these TED arrays. However, any non-zero net misorientation resulting from these arrays is likely to promote instability, ultimately leading to the curvature of the plane. A systematic analysis is being carried out across several wafers and this relationship between the distribution of TED arrays and lattice curvature will be discussed.Reference:[1] N. Ohtani et al. Journal of Crystal Growth 237–239, 1180–1186, (2002).[2] C. Hallin et al, J. Cryst. Growth 181, 241 (1997).[3] R. Singh and M. Pecht, IEEE Industrial Electronics Magazine, 2, 19-31, (2008).[4] Y Chen et al, Materials Science Forum 556, 231-234 (2007).[5] T. Kimoto, et al., Proc. IEEE Int. Rel. Phys. Symp., 2A-1.1–2A-1.7, (2017).[6] M. Dudley, et al, Materials Science Forum, 600-603, 261-266 (2008). Figure 1

Mechanical performance of CNT-reinforced aluminum matrix composite fabricated via flake powder metallurgy: Experimental modeling and molecular dynamics study

In this study, the interactional effects of CNT vol%, milling energy, and temperature on the hardness, tensile strength, and shear strength of Al-CNT composites fabricated through flake powder metallurgy were evaluated experimentally and through MD simulations. The results showed that the CNT content and milling energy significantly influenced the deformation behavior of composite, primarily due to their impact on interfacial bonding strength and dispersion quality. MD simulations were used to study atomistic interactions under loading, including the generation, proliferation, and accumulation of dislocations, slipping of shear planes, and the production of shear bands. These simulations provided insights into the load-bearing mechanisms of CNTs and the nucleation and propagation of dislocations at the interface, which improved the properties of composite. The optimized Al-CNT composite exhibited remarkable properties, with a hardness of 62.8 HB, a tensile strength of 150.7 MPa, and a shear strength of 126.2 MPa, all significantly higher than those of pure aluminum. A confirmatory test demonstrated excellent correlation between experimental and predicted results.

Heterogeneous dynamic recrystallization in the isothermal compression of Ti55-TiBw composite in α + β region

Dynamic recrystallization (DRX) mechanism of the primary α phase (αp) and β phases in the isothermal compression of TiBw reinforced Ti55 composite in the α + β region was investigated by characterizing the grain boundaries misorientation, local strain, subgrain/grain and dislocation morphologies. The results showed the significant heterogenous DRX in both αp and β phases due to the existence of TiBw. The αp recrystallized grains derived from the deformed αp grains either near or away from TiBw were attributed to the continuous dynamic recrystallization (CDRX) mechanism, in which the TiBw accelerated the recrystallization process of the neighboring αp grains. The evolution of β phase away from TiBw displayed the typical discontinuous dynamic recrystallization (DDRX) features. While the β phase near TiBw underwent the CDRX, where the TiBw reinforcements accelerated the accumulation of dislocations and the occurrence of rapid dynamic recovery (DRV). In particular, the effect of TiBw on the DRX was discussed in detail by considering the special crystal structure of TiBw. It was shown that the DRX grains tended to appear next to the incoherent interfaces (101)TiB, (101¯)TiB or the sharp curvature edges, such as tips and growth steps of the whiskers due to the stronger hindering effect for dislocation movement in these regions.

Influence of solution heating rate on grain structures and fatigue crack propagation behaviors of an aviation Al-Li alloy sheet

In this study, the effects of grain structure on the fatigue crack propagation (FCP) behaviors in the aviation Al-Li alloy sheets prepared by varying solution heating rates are discussed systematically. The results reveal that both the intensity of Goss texture and grain dimensions are improved with the decreased solution heating rates. Upon an identical stress intensity factor range (ΔK), the increased Goss texture of the sample with a solution heating rate of 2 ℃/min (2HR) promotes crack deflection, causing a decrease in FCP rates compared to that of the sample with a solution heating rate of about 100 ℃/min (FHR). The dislocations clustered near grain boundaries are more significant with increasing grain size during cyclic loading, which intensifies the strain localization. The accumulation of dislocations increases the possibility of micro-voids formation and creates the conditions for crack deflection, which results in a decrease in FCP rate. Besides, based on the calculation of the reversible plastic zone (RPZ) size, the initial ΔK entering the rapid propagation region increases with decreasing solution heating rates and exhibits a strong linear relationship with grain size.

Surface wear resistance and microstructure characteristic in longitudinal–torsional ultrasonic vibration side milling of GH4169 superalloy

The intrinsic link between the surface wear resistance and microstructural evolution of a material was revealed. The surface wear resistance of the GH4169 superalloy was systematically investigated in relation to the surface machining topography and mechanical properties at different cutting widths in conventional side milling (CSM) and longitudinal–torsional ultrasonic vibration side milling (LTUVSM). The wear resistance was evaluated by analyzing the wear topography, friction coefficient, duration of the initial wear stage (IWS), and wear volume of dry sliding wear. The specimens in LTUVSM exhibited higher wear resistance than those in CSM owing to the inhibition of friction and growth of inter-surface friction nodes by the uniform ultrasonic vibration texture (UVT) and the inhibition of subsurface crack nucleation and extension by the superior mechanical properties. The mechanism of the ultrasonic vibration intervention in grain refinement was revealed. The involvement of ultrasonic vibration enhanced the dislocation accumulation, the grain boundary fractures, and increased the recrystallization fraction, which resulted in a thorough grain refinement with a 7.3 % decrease in average grain diameter (AGD) relative to that obtained with CSM. The increased grain refinement in LTUVSM improved the mechanical properties of the surface-layer material, thereby improving the wear resistance of the specimen.

Microstructure evolution and strengthening mechanism of carbides-reinforced Co–Cr–Nb–W alloy under high-temperature stress-rupture

A novel Co–Cr–Nb–W alloy with a carbide-dominant microstructure was designed in view of the excellent characteristics of NbC and γ-Co matrix to use as wear-resistant components on integral shrouds. The actual service conditions of the alloy were simulated using heat treatment experiments to investigate the influence of high temperature on their microstructure and mechanical properties. The stress-rupture property of the alloy was improved by exposing them to high temperatures. Carbides in the matrix bore the main load under external stress. The fracture mechanism of the Co–Cr–Nb–W alloy is ductile combined with localized brittle failure around large carbides. M6C was formed from the degeneration of MC and decomposition of M23C6 during the heat treatment process along with the two carbides transformation as follows: MC + matrix → M6C and M23C6 + matrix → M6C. The elimination of lamellar M23C6 by carbide transformation and supplemental precipitation of fine M6C around skeleton MC were conducive to longer rupture life. Stacking faults (SFs) played a crucial role in the strengthening mechanism of the Co–Cr–Nb–W alloy. The external stress activated different slip planes in the γ matrix to form “X-shaped” crossing stacking faults (CSFs). Lomer-Cottrell (L–C) locks in CSFs were confirmed by transmission electron microscopy (TEM) under two-beam conditions. SFs can interact with precipitates, dislocations, and grain boundaries to enhance the strengthening mechanism. The SF width was increased by heat treatment, which further increased the dislocation accumulation in the matrix and promoted the formation of CSFs and L–C locks. Therefore, the heat treatments were beneficial to the enhancement of the stress-rupture property of the Co–Cr–Nb–W alloy.

Effect of grain boundary Widmanstätten α colony on the anisotropic tensile properties of directed energy deposited Ti-6Al-4V alloy

Columnar grain structure caused anisotropy in mechanical properties, especially in elongation, is an important concern for Ti-6Al-4 V alloy fabricated by directed energy deposition (DED). Several strategies have been proposed to reduce anisotropy by globularizing the grains, but these conventional approaches are costly and inefficient due to challenges faced during producing the columnar β-grain structures. However, understanding the impact of columnar grain-related microstructures on the anisotropic deformation behavior is still necessary. Despite the recognition of the importance of grain boundary Widmannstätten α colony (αWGB) as a grain-related microstructure, it has received limited attention in available literature on anisotropy in mechanical properties. This study employed in-situ induction heating during DED to control αWGB formation, yielding three Ti-6Al-4 V samples with varying αWGB sizes. Anisotropic deformation of αWGB and its impact on elongation in build and transverse directions were analyzed. αWGB width grew from 0.5 µm to 32.4 µm via diffusion-controlled growth due to reduced cooling rate. Transverse deformation led to dislocation movement and accumulation, causing early failure and worsened ductile anisotropy within αWGB. Notably, larger αWGB size significantly exacerbated anisotropy in ductility. This work underscores αWGB's role in anisotropic deformation and offers insights for optimizing mechanical properties in DED-fabricated titanium alloys.

Microstructural evolution and deformation behavior of an interstitial TRIP high-entropy alloy under dynamic loading

The mechanical properties and microstructural evolution under dynamic loading conditions are of paramount importance in the development and utilization of interstitial high-entropy alloys (iHEAs). This study focuses on the investigation of a currently trending material, C-doped TRIP-assisted HEA Fe49.5Mn30Co10Cr10C0.5 (at.%). By subjecting the alloy to uniaxial quasi-static and dynamic tensile loading, the study systematically elucidates mechanical property testing under different strain states, characterizes the microstructural evolution during deformation, analyzes deformation mechanisms, and delves into the essence of mechanical responses. Particularly, by employing digital image correlation (DIC) techniques, local severe deformation regions under high-speed deformation conditions are sampled to investigate microstructural changes under extreme deformation conditions. The results indicated that, in comparison to quasi-static tensile deformation, the dynamic tensile deformation of the HEA demonstrated a slight increase in yield strength, a decrease in ultimate tensile strength, and a trend toward an increase in total elongation. Specifically, at a strain rate of 103 s−1, the tensile strength was ∼825.5 MPa, and at a strain rate of 10 s−1, the elongation was ∼57.7 %. In quasi-static deformation, the TRIP and TWIP effects served as the primary deformation mechanisms. In dynamic deformation, the proportion of ε-martensite phase transformation was significantly reduced, with deformation twinning (DT) and dislocations becoming the dominant mechanisms, originating from the impact of adiabatic heating on the stacking fault energy (SFE). Furthermore, in the locally severe deformation region, multiple twinning systems were activated, coupled with a substantial accumulation of dislocations. A minor presence of dual-oriented martensite also contributed to this complex mechanism. Additionally, the carbides formed through C-doping exerted a significant hindrance on dislocation slip during high-speed deformation and under high-strain conditions. Simultaneously, they promoted the activation of multiple twinning systems, making an indispensable contribution to maintaining the strain hardening rate (SHR) of the HEA.