Cross-slip Research Articles

Tension-compression asymmetry and the grain-scale slip behavior in untextured Mg-10Gd-3Y-0.5Zr (wt.%)

Mg-10Gd-3Y-0.5Zr (wt.%) is a recently developed high-performance cast Mg alloy with random texture. The present work found that both strength and ductility of this alloy were significantly larger for compression than that for tension, i.e. the mechanical properties exhibited tension-compression asymmetry (TCA), although no twins were observed. To understand this uncommon behavior, the relative activity of individual slip modes and slip-slip interactions during deformation were analyzed in detail at grain scale, based on quasi-in-situ experiments, combined with slip trace analysis and EBSD technique. Significantly asymmetric slip behavior was observed. Although basal slip always dominated for both tension and compression, the relative activity of pyramidal II <c+a> (PyrIICA) slip for tension was 2.6 times higher than that for compression. Statistical analysis of the angle between the active slip plane normal and the loading direction implied that the PyrIICA slip was more easily activated when the slip plane under tension. The asymmetric activity of PyrIICA slip was believed to contribute to the observed yield strength TCA. What’s more, almost all possible combinations of cross slip and slip transfer for total 30 slip systems were only observed during compression and analyzed in detail. The strong slip-slip interactions induced by massive cross slips and effectively accommodated intergranular deformation by slip transfer were consistent with the well-balanced strain hardening, which resulted in improved ultimate strength and ductility for compression.

Hot extrusion, tensile deformation behavior and deformation mechanism analysis of a wrought superalloy with a high γ′ phase volume fraction of 64 %

A hundred kilograms of GH4975 extrusion bar, featuring fine equiaxed grains, were successfully fabricated using electron beam smelting layer solidification(EBSL) and hot extrusion techniques. Subsequent analysis focused on the microstructure and tensile properties of the extruded bar. The study also delved into the influence of temperature on tensile deformation behavior and mechanisms of the alloy after standard heat treatment(SHT). The results revealed uniformity in precipitated phase size and morphology across the extruded bar, with grain size being the largest at the center and smallest at the edge. Tensile tests conducted at 20 °C and 650 °C show an obvious work hardening phenomenon, and the deformation mechanism is dominated by APB coupled dislocation pairs shearing. With the increase of deformation temperature, the work-hardening phenomenon gradually weakens, and SFs emerge as the primary deformation mechanism at 750 °C. As the deformation temperature further rises, cross slip, Orowan bypass and dislocation climbing gradually dominate. The fracture mode changes from brittle fracture to ductile and brittle mixed fracture, and ultimately to brittle fracture. Compared with the traditional preparation method, the hundred kilograms of GH4975 extrusion bar prepared by this technology still show better mechanical properties.

EFFECTS OF TEMPERATURE AND STRAIN AMPLITUDE ON LOW-CYCLE FATIGUE PROPERTIES OF NICKEL-BASED SINGLE-CRYSTAL SUPERALLOY DD419

High-temperature and low-cycle fatigue tests were conducted on a nickel-based single-crystal superalloy DD419 under total strain-controlled conditions at 760 °C and 980 °C. The fatigue properties of the alloy are discussed by analysing the fatigue test data. Fracture morphology and dislocation structure were observed using scanning electron microscopy and transmission electron microscopy. At the same strain amplitude, the results indicate that the plastic deformation of the alloy is larger at 980 °C compared to 760 °C. This leads to a lower fatigue strength and shorter fatigue life, along with more severe damage. The value of the strain amplitude affects the cyclic stress response behaviour of the alloy. Under low strain amplitudes, the cyclic stress response behaviour differs between 760 °C and 980 °C. The hysteresis loop exhibits similar shapes at 760 °C and 980 °C, with an increase in the area as the strain amplitude rises. The fatigue fracture analysis indicates that micropores on the surface are the primary fatigue sources at 760 °C, while oxides on the surface are the main fatigue source at 980 °C, leading to cracking due to multiple sources. Moreover, transmission electron microscopy reveals that the deformation mechanism involving dislocations at 760 °C primarily occurs through plane slip and wave slip, whereas at 980 °C, dislocations mainly move through cross slip and climb.

Microstructure and strength of cold-drawn large strain Fe35Ni35Cr20Mn10 high-entropy alloy

The Fe35Ni35Cr20Mn10 high-entropy alloy wires can achieve a large strain of 8.73 and a section reduction ratio of 99.98 %,and possess a high strength of 1868 MPa via traditional wire drawing. The microstructure evolution and mechanical properties of cold-drawn Fe35Ni35Cr20Mn10 high-entropy alloy are characterized by microstructure observation and tensile test. The results showed that The Fe35Ni35Cr20Mn10 HEA has excellent plastic forming capacity and excellent phase stability during plastic deformation. The Fe35Ni35Cr20Mn10 HEA has excellent continuous drawing ability, the main deformation mechanism is the plane slip and cross slip of the dislocation and the dynamic recovery of the sublamellar layer make the lamellar structure maintain a dynamic equilibrium state, and the lamellar thickness is basically unchanged to support the continuous plastic deformation under high strain conditions. The dynamic balance of coarsening and refining of lamellar structure in the process of plastic deformation is mainly due to the merging of HEA lamellar caused by the movement of trigeminal node induced by strain. Texture evolution showed that the <111> and <100> fiber textures were the stable texture component and the texture component content remained unchanged even under further increased strain. The Fe35Ni35Cr20Mn10 high-entropy alloy wire with high strain of 8.73 possesses excellent strength, and its tensile strength is 1868 MPa at room temperature, which has the largest strain. The dislocations proliferation, lamellar structure refinement and texture strengthening lead to high strength of the Fe35Ni35Cr20Mn10 high-entropy alloy wire.

Local heating at the running crack tip in bcc iron according to molecular dynamics

Abstract This study presents estimates of a possible temperature rise at the crack tip from three dimensional (3D) atomistic simulations of fracture via molecular dynamics (MD) technique. Simulations start from an initial temperature of 0 K. The pre-existing edge crack was loaded in tension mode I. Crack initiation in MD is accompanied by surface dislocation emissions and later by a cross slip of the emitted dislocations into other slip systems. This leads both to stress waves radiation and to local heating in the plastic zone created by these dislocations. The local heating at the crack tip in the surface layers reaches a level of 480–500 K at some atoms, but an average temperature in the plastic zone is lower and depends on a chosen crack tip zone size. In the bulk crystal, where no dislocation emission (i.e. no plastic zone) has been realized, no significant heating is observed at the crack tip. MD results at the free sample surface comply with experimental data for ferritic steels with a pre-existing notch, loaded (quasi-statically) in mode I, as well as with some continuum predictions.

Unveiling the temperature-dependent deformation mechanisms of single crystal gallium nitride in nanoscratching

The surface grinding process of single crystal gallium nitride (GaN) is intricate, and localized high temperature generated during interactions between the workpiece and the abrasives on grinding wheel is inevitable. Elevated temperatures significantly affect the deformation mechanisms of GaN, which remains inadequately elucidated. In this study, nanoscratching experiments were systematically conducted on the (0001) plane of GaN single crystal across a temperature range up to 500 ℃, and the resultant deformation patterns were thoroughly characterized. The results indicate that temperature elevation delays the brittle-to-ductile transitions in GaN and enhance its anisotropy. Additionally, GaN exhibits increased plasticity as temperature rises, leading to distinct scratch-induced subsurface deformation patterns at varying temperatures: at room temperature, the thickness of the subsurface damaged layer is primarily influenced by the penetration depth of cross slips, whereas at 500 ℃, basal slipping predominantly defines the thickness of the subsurface damaged layer. The plastic deformation patterns at both room temperature and 500 ℃ mainly involve phase transition, polycrystal formation, slips, stacking faults, dislocations and lattice distortions. The discrepancies in deformations at varying temperatures were thoroughly investigated by transmission electron microscopy and molecular dynamics simulations, and the underlying mechanisms were elucidated.

New insights from crystallography into the effect of Ni content on ductile-brittle transition temperature of 1000 MPa grade high-strength low-alloy steel

The significant effect of Ni content (0.92, 1.94 and 2.94 wt%) on ductile-brittle transition temperature (DBTT) and microstructure in a 1000 MPa grade high-strength low-alloy (HSLA) steel was studied. Using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), Charpy impact test and low-temperature tensile test to study the fundamental reasons for the effect of Ni content on toughness. The results indicated that increasing the Ni content can reduce the DBTT of HSLA steel and improve the impact toughness at low temperatures. EBSD data post-processing analysis revealed that the key reason for the increase in low-temperature toughness is the refinement of the microstructural crystallographic structure, specifically the significant increase in the boundary density of the block and packet. With the increase of Ni content, the density of grain boundary with an orientation difference greater than 5° between two adjacent {110} crystal planes was higher, which can form a higher density of dislocation pile-up group, thus better reducing local stress concentration. Meanwhile, the stacking fault energy (SFE) increases with the increase of Ni content, which made the screw dislocation more prone to cross slip at low temperature, resulting in an increase in plasticity at low temperatures. These observed phenomena and reasons provided a theoretical explanation for the role of Ni content in reducing DBTT and enhancing the toughness of the core in heavy gauge plates.

Influence of texture on anomalous yielding behavior of thermomechanically processed nickel-based superalloy 720Li

Precipitation-strengthened Ni-base superalloys are extensively used for high-temperature load-bearing applications due to their unique combination of yield stress anomaly (YSA), excellent creep, fatigue, and corrosion resistance. However, in line with the previous reported results, it is shown in the present study that 720Li alloy does not exhibit YSA during uniaxial deformation. The investigation explores the role of anti-phase boundary (APB) energy, Zener ratio and break away stress of Kear-Wilsdrof (KW) lock on YSA behavior. It is shown that in spite of meeting all the energetic requirements necessary for YSA (viz. energy for octahedral to cubic cross slip along with high break away shear stress, i.e. ∼ 80 MPa); the thermo-mechanically processed 720Li alloy does not exhibit YSA. In support of the observed absence of YSA, a plausible mechanism is provided for the first time through this work. This unusual absence of YSA has been attributed to the crystallographic texture of the alloy (specifically, the loading direction (LD) being parallel to [11¯1]), which prevents the formation of KW-locks in the first place. The [11¯1] texturing has been shown to rather lead to direct cubic plane slip i.e. {001} <110>, thereby paving way for suppression of KW-locks (and hence YSA). In order to validate this postulate, the study also examines a vacuum induction melt and cast Ni75(Al11, Ti14), L12 compound. The presence of YSA in the L12 compound under conditions of LD not being parallel to [11¯1], confirms that texturing impacts the occurrence of YSA.

Promoting grain refinement and nanocrystal generation in surface nanomachining by means of overlapping collisions

Surface nanostructuring effectively improves the mechanical properties and wear resistance of the moving parts, yet a thorough understanding of its formation mechanism remains elusive. This study examined the microstructure evolution of pure copper under various linear overlapping ratios (φ) using a self-made impact wear tester. The results revealed that high Smid factor grains activate the basal slip system to handle deformation during repeated impacts. Still, overlapping impacts can intensify plastic deformation by activating multiple slip systems and boosting dislocation proliferation. Moreover, overlapping collisions will generate Frank's incomplete dislocations, hindering dislocation slip and generating cross slip trajectories, resulting in the bending of slip-trajectories, the formation of uneven wrinkles, and the refinement of superficial grains.

Influence of microstructure characteristics on the fatigue properties of 7075 aluminum alloy

Grain size and aging state are the two major microstructural factors affecting the mechanical properties of Al alloys. In this study, fatigue tests were conducted on 7075 Al alloy with varying grain sizes and aging states. The results indicate that both grain refinement and over aging (OA) treatment are beneficial for enhancing fatigue performance, with the 7075-Min alloy exhibiting the highest fatigue strength of 265.8MPa in the OA state. For grain size, a quantitative positive linear relationship was found between the reciprocal of the square root of the average grain size and the fatigue strength coefficient. Grain refinement optimizes the fatigue performance by increasing the fatigue strength coefficient. Compared to the under aging (UA) state, OA treatment promotes the growth and coarsening of precipitates at grain boundaries (GBs) and within the interior of grains. This change in precipitate morphology effectively facilitates dislocation cross slip, reducing fatigue damage caused by dislocation blocking. The impact of the precipitation-free zone (PFZ) on fatigue performance is negligible compared to that of the precipitates. This study clarifies the relationship between microstructure and fatigue performance, providing valuable insights for microstructure regulation to optimize the fatigue performance of Al alloys.

Size effect and underlying microstructural mechanism in cyclic deformation behavior of nickel-based superalloy sheet

The nickel-based GH4169 superalloy is widely used in the aerospace field, which has desirable oxidation resistance and strength in extreme environments. However, the size effect and underlying microstructural mechanism in the cyclic deformation of the GH4169 sheet are still not fully elucidated, which affects the forming accuracy precision of thin-walled components. To this end, the cyclic mechanical properties and microstructural evolution of the GH4169 sheets with different thicknesses and grain sizes were systematically investigated via cyclic shearing tests. The superalloy sheet exhibits obvious early re-yielding, instantaneous softening and permanent softening during the cyclic deformation and these cyclic deformation behaviors are obviously affected by size effect. To rationalize the cyclic mechanical responses and size effect, transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) tests were conducted. The results indicated that the dislocation slip patterns are principally planar array slip and cross slip in the cyclic shearing deformation. Meanwhile, the annihilation of unstable dislocation and the presence of carbides led to the instantaneous softening. Moreover, the change of loading direction, the reduction of texture strength, the proportion of low-angle grain boundary (LAGB), and geometrically necessary dislocation (GND) density together result in the occurrence of permanent softening. Based on the comparative analysis of the microstructure evolution of superalloy sheets with different size factors, the underlying mechanism of size effect on cyclic deformation was clarified. The findings in the research combine the cyclic mechanical response and microstructure evolution closely in the cyclic deformation of superalloy sheets and deepen the understanding of size effect under complex loading paths.

Hot compression deformation behavior and microstructure evolution of Al-0.5Mg-0.4Si alloy

The hot compression tests for as-cast Al-0.5Mg-0.4Si alloy were performed on Gleeble-3500 thermo-mechanical simulator under temperatures of 350–500 °C and strain rates of 0.01–10 s−1. Based on the experimental data, a strain-compensated Arrhenius constitutive model was established by exponential function coupling strain. The hot processing map of Al-0.5Mg-0.4Si alloy was established, and the reasonable processing parameters were obtained. The microstructural evolution and dynamic softening mechanisms of the alloy were analyzed using electron backscatter diffraction (EBSD). A detailed description of the evolution of dislocation and the dislocation density during the deformation process was provided. The results indicate that the softening mechanisms of Al-0.5Mg-0.4Si alloy are dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX). The dynamic recovery mechanism is related to the cross slip of the screw dislocation. High temperature and low strain rate are conducive the occurrence of CDRX. This study provides comprehensive guidance for the hot processing of Al-0.5Mg-0.4Si alloy from both macroscopic and microscopic perspectives.

Unique damage process in micro-sized copper single crystal with double-slip orientation in response to near-[112] tension-compression fatigue

In order to clarify the fatigue process for a micro-sized copper (Cu) single crystal with a double-slip orientation, a tension-compression cyclic loading test was carried out with in situ FE-SEM observation. Although the primary slip system B4 finally brought about a crack from eminent intrusions, the process was complex due to characteristic interactions among multiple slip systems. The process was approximately divided into three stages; early slipping, cave-in and damaging. In the early stage, two slip systems with high Schmid factor (SF), B4 and C1, worked at first, however both immediately stopped working. Extrusions/intrusions were caused by the survived slip system B5 (third-highest SF). In the second stage, a triangular depression was brought about by the cross-slip from B5 to C5 and localized wavy undulation was formed by the continuous cross slips. In the final stage, though both of B4 and B5 worked, the slip system with the highest SF, B4, dominated to form the eminent extrusions/intrusions, resulting in the fatigue cracking. The applied resolved shear stress amplitude was a few megapascals, indicating significantly lower fatigue strength than that of the bulk counterpart while it was in same range for that of micro-sized Cu with a single slip orientation. The complex fatigue damage morphology of the specimen was explained by accounting for the interaction of dislocations between the slip systems.

Solute clustering and its role in a titanium alloy made by laser powder bed fusion

In recent years, atomic clusters and composition undulation have been observed in a number of concentrated solid-solution alloys and were found to be beneficial for strength-ductility synergy. Some reports are also available on the observation of atomic clusters in body-centred cubic metastable β titanium alloys but the role of these atomic clusters in mechanical property development is unclear. In this study, we report the formation of solute atomic clusters in an additively manufactured and solution-treated metastable titanium alloy and investigate their role in deformation and strengthening mechanisms. It was found that the atomic clusters together with ultrafine ω precipitates present in the material effectively pin dislocation motion and contribute to an ultrahigh yield strength. The interaction between dislocations and solute atomic clusters leads to an increased shear stress necessary for dislocation motion. The atomic clusters and the resulting chemical undulation generate pronounced atomic strain fluctuations and distortions with alternating tensile and compressive strain fields, which lead to large local internal stresses and thus resistance to dislocation glide. Cross slip has also been frequently observed in the additively manufactured and solution-treated metastable titanium alloys, which is beneficial for strain hardening and ductility. We also reveal that thermal cycling in the alloy can lead to a significant influence on the microstructural evolution. During solidification and cooling upon laser powder bed fusion, only β and athermal ω precipitates form. With repetitive thermal cycling, the microstructure transforms into α + β grains together with isothermal ω particles. The present findings suggest that solute atom clustering can be introduced through proper selection of solute elements, providing a new strengthening mechanism for titanium alloys.

Achieving high strength-ductility synergy via Guinier-Preston zone formation in a new Mg–Zn–Al–Ca–Mn–Ce sheet alloy

ZAXME11100 (Mg–1Zn–1Al-0.5Ca-0.4Mn-0.2Ce, wt.%) is a recently developed sheet alloy with excellent formability at room temperature. The yield strength of this alloy is significantly improved by a short 1-h aging treatment at 210 °C (T6), from 159 MPa in solution-treated state (T4) to 270 MPa in the T6 condition, with a slight reduction in tensile elongation (from 31 % in T4 to 26 % in T6). In this work, precipitation microstructure was characterized to explain the aging hardening and high strength-ductility synergy of the new alloy. A high density (8 × 1023/m3) of ordered monolayer Guinier-Preston (GP) zones enriched in Al, Ca and Zn uniformly form on the Mg basal planes after T6 treatment. Grain boundary segregation of Al, Ca and Zn is also observed. Deformation microstructure of T4 and T6 samples tested to various strain levels was examined. At small strain levels, basal and non-basal <a> dislocation slip dominates the deformation process, and cross slip of <a> dislocations between basal and non-basal planes is observed in T6 samples. The GP zones are gradually destroyed by plastic deformation. Based on those results, the strengthening contribution of ordered GP zones was modeled to be 116 MPa. Therefore, formation of GP zones is an effective way to achieve high strength-ductility synergy in wrought Mg alloys.

Research on microplastic deformation of Inconel718 under the conditions of high temperature and high strain rate

The compression experiments of the nickel-based superalloy Inconel718 were carried out with the help of split Hopkinson pressure bar device, and the microstructure evolution law in the compression deformation of the alloy was studied by means of optical microscopy, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Based on the dislocation theory, a three-dimensional discrete dislocation dynamics model is established. By simulating the dynamic evolution of the discrete dislocation, the interaction of the dislocation itself and the formation of the dislocation microstructure were captured, and further explore the microplastic deformation process of Inconel718. The results show that deformation conditions significantly affect the rheological behavior and dynamic recrystallization behaviour. The cross slip of dislocations is closely related to temperature and strain rate, which in turn affect the dislocation configuration. The deformation mechanism of Inconel718 under the conditions of high temperature and high strain rate is jointly dominated by dislocation slip and twin deformation. As the temperature increases, the average Schmidt factor increases, and more dislocation slip systems are activated. As the strain rate increases, the number of deformation twins increases, while the thickness of deformation twins decreases.

Cross slip based dynamic recovery during plane strain compression of aluminium and its role in preferential nucleation of the cube-oriented recrystallized grains

Understanding nucleation of the cube-oriented grains during static recrystallization of medium to high stacking fault energy (SFE) FCC metals is both scientifically and industrially important. Dynamic recovery due to weak Hirth junctions is considered as one of the plausible explanations for the nucleation advantage of the cube orientation. However, influence of cross slip based dynamic recovery on the nucleation propensity of the cube orientation has not been studied in detail. For this purpose, we explicitly incorporated stress dependent dynamic recovery of screw dislocations into a dislocation density based crystal plasticity model. The model is utilized for studying influence of cross slip based local dynamic recovery during deformation and recrystallization nucleation of aluminium. We show that dynamic recovery influences local dislocation density difference and disorientation with the neighbouring locations for the main rolling texture components. Next, we analysed nucleation propensity of these texture components using a stochastic nucleation model. Simulation results show that without explicit incorporation of the dynamic recovery of screw dislocations, the Goss orientation shows the highest nucleation propensity. On the other hand, incorporation of the cross slip based dynamic recovery enhances nucleation propensity of the cube component. Therefore, cross slip based dynamic recovery is one of the important mechanisms for nucleation of the cube-oriented recrystallized grains. These results provide new insights into deformation and recrystallization nucleation of medium to high SFE FCC metals.

Effect of Si on the deformation behavior of retained austenite and annealed martensite in medium Mn steels

The present study systematically investigated the effect of Si additions from 0 to 4 wt % on the deformation mechanism of a Fe-0.2C-6.8Mn (wt. %) medium Mn steel. The duplex microstructure consisting of film-like retained austenite (RA) and lath-shaped annealed martensite (AM) was produced for different Si alloyed steels by annealing treatments. They have similar volume fraction of RA. The effect of Si content on the dynamic strain aging (DSA) of RA and the serration type of tensile curves, as well as the fine structure evolution within AM during deformation was studied in detail. For the different Si alloyed steels, their tensile curves all exhibit flow serrations, accompanied with the propagation of the Portevine-Le Châtelier (PLC) band caused by DSA in RA. The serration type was sensitive to Si content. For the high Si steel, only type B serrations appear. This is attributed to the high Si content in RA, promoting aged dislocations by C atoms due to the repulsive interaction between C and Si atoms. For the low Si and Si free steels, type A serrations occur after type B serrations disappear at a certain strain. The mechanical stability and Mn/Si contents of RA play an important role in the PLC band propagation. The Si content has also an important effect on the evolution of dislocation configuration within AM during deformation. In the low and Si free steels, the dislocation multiplication and tangles, as well as the formation of dislocation walls, dividing up the laths appear in the AM. While in the high Si steel, it is found that the dislocation cells appear within the AM due to Si addition promoting the formation of screw dislocations by neutron diffraction technique, and the cross slip of screw dislocations as a necessary mechanism for dislocation cell formation. The formation of dislocation configuration with low energy is believed to be another essential factor improving the mechanical properties, besides the transformation-induced plasticity effect. This work paves a new pathway towards tailoring dislocation configuration for designing a new generation advanced high-strength steel.

Negative enthalpy alloys and local chemical ordering: a concept and route leading to synergy of strength and ductility.

Solid solutions are ubiquitous in metals and alloys. Local chemical ordering (LCO) is a fundamental sub-nano/nanoscale process that occurs in many solid solutions and can be used as a microstructure to optimize strength and ductility. However, the formation of LCO has not been fully elucidated, let alone how to provide efficient routes for designing LCO to achieve synergistic effects on both superb strength and ductility. Herein, we propose the formation and control of LCO in negative enthalpy alloys. With engineering negative enthalpy in solid solutions, genetic LCO components are formed in negative enthalpy refractory high-entropy alloys (RHEAs). In contrast to conventional 'trial-and-error' approaches, the control of LCO by using engineering negative enthalpy in RHEAs is instructive and results in superior strength (1160MPa) and uniform ductility (24.5%) under tension at ambient temperature, which are among the best reported so far. LCO can promote dislocation cross-slip, enhancing the interaction between dislocations and their accumulation at large tensile strains; sustainable strain hardening can thereby be attained to ensure high ductility of the alloy. This work paves the way for new research fields on negative enthalpy solid solutions and alloys for the synergy of strength and ductility as well as new functions.

Bidirectional phase transformation facilitated by ε-martensite bands interaction in metastable Fe50Mn30Co10Cr10 dual-phase high entropy alloys

The phase transformation-induced plasticity (TRIP) metastable Fe50Mn30Co10Cr10 dual-phase high entropy alloys exhibit an excellent combination of strength and ductility. The interaction between ε-martensite (HCP phase) bands plays a fundamental role in determining the mechanical properties of Fe50Mn30Cr10Co10 alloys. In this work, the phase transition mechanism of Fe50Mn30Co10Cr10 dual-phase high entropy alloy was studied by using electron backscatter diffraction (EBSD), transmission electron microscope (TEM) observation and molecular dynamic (MD) simulations. The results indicated that the orientation relationship and character of the ε-martensite band play a crucial role in the phase transition and growth of ε-martensite bands. As an expanding ε-martensite band is obstructed by another ε-martensite band, the cross slip or dissociation of the Shockley partial dislocations at the ε-martensite junction lead to the growth of the ε-martensite bands. When two ε-martensite bands form a cross structure and the phase transition partial dislocations of the incident ε-martensite band are edge type, a new FCC-structured grain will be formed in the domain where the ε-martensite bands intersect. While the dissociation and gliding of Shockley partial dislocations at the phase boundaries will lead to the growth of the ε-martensite bands when the phase transition dislocations of the incident ε-martensite band are mixed type.