Dislocation Evolution Research Articles

Strain-rate-dependent behaviors of CoCrNiSi0.2 medium-entropy alloy: Deformation mechanism and microstructural-based constitutive modeling

Abundant strengthening mechanisms in medium-entropy alloys (MEAs) endow them with excellent comprehensive properties, rendering them promising candidates for use in extreme service conditions, such as low/high temperatures and strong impact environment. Investigation of the mechanical behaviors and micro deformation mechanisms of MEAs under intermediate/high strain rate loadings should therefore help to explore their application potential in impact-resistant structures. In this study, the tensile mechanical properties of a single-phase face-centered cubic (FCC) CoCrNiSi0.2 MEA were tested over low, intermediate, and high strain rates, and the micro deformation mechanisms at different strain rates were analyzed systematically. Dislocation evolution, deformation twinning, and phase transformation (from single FCC to FCC + hexagonal close-packed (HCP)) were observed in the three groups of tensile specimens loaded at low, intermediate, and high strain rates. The dislocation densities and twin volume fractions in the three groups were comparable, while the volume fraction of phase transformation increased significantly with the increasing strain rate. Therefore, more HCP phases generated during high-strain-rate deformation should lead to a stronger precipitation-strengthening effect on the material, which made the strain-rate-strengthening effect more significant to the extent that it could not be ignored in constitutive modeling. Finally, the contribution of the phase transformation was introduced for the first time into a constitutive model in which dislocation slip and deformation twinning were also considered to describe the viscoplastic flow behavior of the CoCrNiSi0.2 MEA over a wide range of strain rates.

Mechanical characteristics and deformation behavior of Al polycrystal reinforced with SiC particles

Molecular dynamics models are established to investigate the influence of silicon carbide (SiC) particle size and strain rate on the mechanical characteristics and deformation behavior of aluminum (Al)/SiC composite. The results show that the ultimate strength of the Al/SiC composite increases from 0.788 to 0.910 GPa as the SiC reinforcement particle size increases from 10 to 30 Å, due to load transfer effects and barriers to dislocation motion. Plastic deformation of Al/SiC composite decreases with increasing SiC particle size, manifested by a lower proportion of atoms subjected to high shear strain for larger SiC particles. The SiC particle size also influences the change in crystal structure during deformation, as shown by the larger particles better supporting the Al matrix in minimizing the dislocation movement. The study shows that the grain boundary and Al/SiC interface play a significant role in the mechanical properties of the composite by impeding the evolution of dislocation and stacking fault. Moreover, the higher strain rates lead to increased ultimate strength and flow stress due to a greater rate of deformation and energy storage. The distribution of shear strain in the composite shows concentrated deformation at the grain boundary, and the large shear-strain region decreases as the strain rate increases. Additionally, higher strain rate leads to more formation of hexagonal-close-packed and amorphous structures, increased dislocation density, and material failure.

Dynamic Spheroidization Mechanism and Its Orientation Dependence of Ti-6Al-2Mo-2V-1Fe Alloy during Subtransus Hot Deformation.

The dynamic spheroidization mechanism and its orientation dependence in Ti-6Al-2Mo-2V-1Fe alloys during subtransus hot deformation were studied in this work. For this purpose, hot compression tests were carried out at temperatures of 780-880 °C, with strain rates of 0.001-0.1 s-1. Based on SEM, EBSD and TEM characterization, the results showed that the aspect ratio of the α phase decreased with increasing deformation temperatures and decreasing strain rates. At 880 °C/0.001 s-1, the aspect ratio of the α phase was the smallest at 2.05. The proportion of HAGBs decreased with increasing temperatures and strain rates, which was different from the trend of the spheroidization; this indicated that the formation of HAGBs was not necessary for the spheroidization process. Furthermore, the formation of the α/α interface was related to the evolution of dislocations and twin boundaries at high (880 °C) and low temperatures (780 °C), respectively. Moreover, the dependence of lamellar spheroidization on the crystallographic orientation tilt from the compression direction (θ) was clarified: when θ was between 45° and 60°, both the prism <a> slip and basal <a> slip systems were activated together, which was more favorable for spheroidization. This study could provide guidance for titanium alloy process designs and microstructure regulation.

Microstructural evolution of cast super austenitic stainless steel during hot compression

In the present paper, the effect of strain on the microstructure evolution of 7Mo-0.42N contained cast super austenitic stainless steel (SASS) during compression deformation at 1200 °C was systematically studied to optimize the hot working process. The dynamic recrystallization (DRX) grains size, recrystallization mechanism, annealing twin characteristics, and dislocation evolution during high-temperature deformation at varied strains were examined. Results show that the recrystallization behavior of the SASS during high-temperature compression can be divided into three stages. In stage I, the parent grain boundaries were gradually replaced by recrystallized grains, and observed both cyclic grain refinement and coarsening of grains. In stage II, the recrystallized grains elongated into the parent grain interior from the boundaries until the parent grain was completely covered. Meanwhile, the DRX and abnormal grain growth occurred simultaneously and developed rapidly at this stage. At stage III, the recrystallized grains abnormally grew to ∼76 μm and was deformed again because of the increased strain. The nucleation mechanism also changed during deformation. The discontinuous dynamic recrystallization (DDRX) dominated at stage I and II (ε = 0.1–0.6) with relatively low deformation strain. While in the high strain range of stage III (ε = 0.7–1.0), the continuous dynamic recrystallization (CDRX) took over. These quantitative statistics and analyses of data were carried out in terms of recrystallization grain size and nucleation mechanism under different strain variables, providing experimental basis and theoretical guidance for the production of SASS.

Revealing the acoustic effects on heat transfer and material flow in ultrasonic assisted friction stir welding of dissimilar Al/Mg alloys

Development of a reasonable constitutive equation is critical to realize accurate numerical prediction of ultrasonic vibration-assisted friction stir welding (UVaFSW) of dissimilar Al/Mg alloys and deepen the understanding of the synchronous interaction between the ultrasonic vibration exerted on the tool and the tool induced thermo-mechanical behavior. Considering the thermal activation and dislocation evolution mechanisms, the calculation method of acoustic stress work based on the change of dislocation strain energy is redefined, and a modified acoustic-plastic constitutive equation is developed. The modified constitutive equation was applied to the computational fluid dynamics (CFD) model combined with the volume of fluid (VOF) method and quantitative analysis was conducted on the acoustic effects on heat generation, material flow and intermixing in UVaFSW of Al/Mg alloys. The results indicate that the exerted ultrasonic vibration has a little effect on the total heat due to the multiple effects of acoustic softening, acoustic antifriction and additional acoustic heat, but can promote the material flow around the tool and expand the material intermixed region. The experimental research validates the calculated results, and it is indicated that the flow stress and temperature field calculated by the improved constitutive equation have higher accuracy in UVaFSW of Al/Mg alloys.

Mesoscale modelling of dislocation evolution: Physically based requirements on stochastic differential equations

The complexity of collective dislocation behaviour has motivated the use of mesoscopic models, which describe the average behaviour of dislocations. Due to the statistical nature of such models, it has been argued that a stochastic theory provides a more complete physical description. A number of stochastic differential equation (SDE)-based dislocation models have been proposed over the past three decades; however, there is no generally accepted method for transforming a deterministic model into a stochastic model. A range of approaches exist in the literature, but the choice of method is ad hoc and their physical consequences are not considered. Such transformations therefore may not preserve certain properties of the corresponding deterministic theory, namely that of non-negativity of the dislocation density. In the present work, we show that the drift and diffusion coefficients must extend to zero on the semi-closed interval [0,∞) to guarantee non-negativity of the dislocation density. We also demonstrate the breakdown of non-negativity in SDE-based dislocation models through analytical treatment of a class of mesoscale models, and propose a possible modification. We bring to attention a physically motivated method for deriving stochastic models which preserves non-negativity, and in general ensures that trajectories exist almost surely in some given set, so that it obeys the desired physical bounds on the state variables — called the stochastic invariance principle. These results can provide a better understanding of dislocation models used to describe microstructural damage accumulation in metallic structures, which can be incorporated into fatigue lifing models.

Hot deformation behavior and dynamic recrystallization mechanisms of GH4975 alloy prepared by electron beam smelting layered solidification

In this work, the hot deformation behavior and dynamic recrystallization mechanisms of GH4975 prepared by electron beam smelting layered solidification were studied. The friction and temperature correction were applied to the stress-strain curves, and the constitutive equation were established and the hot deformation activation energy was calculated to be 1449.748 kJ/mol. Thermomechanical processing map of GH4975 alloy was build and verified by deformation microstructures. Additional, the microstructure evolution and dynamic recrystallization (DRX) mechanisms were analyzed in detail by electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The evolution of dislocation and the dislocation density are characterized in detail during deformation. The results show that high temperature and low strain rate were conducive the occurrence of DRX. Three DRX mechanisms can be discovered during deformation. The recrystallization mechanism of GH4975 alloy is dominated by discontinuous dynamic recrystallization(DDRX) characterized with grain boundary bulging, and assisted by continuous dynamic recrystallization(CDRX) characterized with subgrain rotation. Additional, twin boundaries-induced nucleation (TDRX) can be as supplementary nucleation mechanism.

Unravelling anisotropic deformation behaviour of Ti-6Al-4V ELI fabricated by powder bed fusion additive manufacturing

The uniaxial compression tests with respect to the different loading directions (i.e., parallel, and perpendicular to the building direction) were performed to investigate the anisotropic deformation mechanism of Ti–6Al–4 V ELI (extra low interstitial) alloy fabricated by laser powder bed fusion (L-PBF). The tests showed anisotropic mechanical properties; the sample loaded perpendicular to the building direction (TDx) has a higher fracture strain and lower yield strength, but a superior hardening effect than those of the sample loaded along the building direction (BD). Electron backscatter diffraction (EBSD) and digital image correlation (DIC) analyses were conducted used at regions of interest (ROI) in as-built and deformed samples. The kernel average misorientation (KAM) analysis revealed that a trend of dislocation evolution is strikingly different according to the loading directions; uniform KAM distribution is observed in the BD sample, whilst localization at prior β grain boundaries is found in the TDx sample. In addition, it was identified via a microscopic strain distribution map that the unique layered microstructure (i.e., layer band) and prior β grain boundary are more sensitive to compressive loading than the surrounding matrix. The layer band and prior β grain boundary were formed with their directivity during the additive manufacturing process; thus, their morphology is different depending on the loading direction. As a result, the layer band and prior β grain boundary play a key role in anisotropic behaviour, more precisely, the anisotropic deformation behaviour originates from the morphology of the layer band and β grain boundary, which is changed with respect to the loading direction.

Study on the Microscopic Mechanism of Axle Steel EA4T during Uniaxial Cyclic Deformation Process

In order to reveal the dislocation evolution law of body-centered cubic axle steel EA4T during cyclic deformation and provide an experimental basis for the subsequent construction of cyclic constitutive models based on microscopic physical mechanisms, macroscopic deformation experiments were first conducted on axle steel EA4T, including monotonic tensile experiments under different deformation amounts, symmetric strain cycling experiments under a different number of cycles, and ratcheting deformation experiments under a different number of cycles. Then, systematic observations of different samples at different deformation stages were conducted using a Transmission Electron Microscope (TEM) to investigate the dislocation configuration and evolution during strain cycling and ratcheting deformation. The observed results show that the dislocation evolution law of axle steel EA4T during the uniaxial tensile experiment, symmetrical strain cycling, and ratcheting deformation is basically the same, and the dislocation density increases with the increase in plastic deformation and number of cycles. The dislocation configuration gradually develops from low-density dislocation configurations such as dislocation lines and dislocation pileups to high-density dislocation configurations such as severe dislocation tangles and dislocation walls. The microscopic mechanism of the uniaxial ratcheting evolution of axle steel EA4T can be qualitatively explained by the dislocation configuration and evolution.

Effect of Cu and Mg co-segregation on the strength of the Al grain boundaries: A molecular dynamics simulation

Molecular dynamics simulations employing machine learning potential functions of Al-Cu-Mg ternary alloys, were performed to elucidate the segregation behavior of Cu and Mg solutes and study their effects on the mechanical properties of Al grain boundaries. The calculation results show that Cu segregation enhances the strength of the Al Σ5 (210)[001] grain boundary, while the Mg instead weakens the Al Σ5 (210)[001] grain boundary. Cu and Mg solutes lead to the Al Σ41 (540)[001] grain boundary embrittlement. Dislocation plays a crucial role in the analysis of plastic deformation. We found that the reinforcing effect of the Cu solutes lies in the dislocation pile-up in plastic deformation, and the stair-rod dislocations inhibited the movement of the Shockley dislocations. The embrittlement cause of Mg solutes is that Mg solutes inhibit dislocation emission and shorten the dislocation nucleation cycle. This work illustrates the relationship between solute strengthening mechanism and dislocation evolution at the atomic scale.

Effect of hydrogen on the dislocation evolution in an aluminum alloy under cyclic loading by two-dimensional discrete dislocation dynamics

The aim of this research is to reveal the effect of hydrogen on fatigue crack initiation in an aluminum alloy. First, the effect of hydrogen on the dislocation movement, that is, the hydrogen-enhanced localized plasticity (HELP), was modeled. Two mechanisms of HELP were modeled: reduction of the dislocation interaction stress and an increase of the dislocation velocity by hydrogen. Next, simulations of the early stage of crack initiation were performed by discrete dislocation dynamics with the HELP model. The simulation results indicated that HELP accelerates fatigue crack initiation and the increase of the dislocation velocity by hydrogen is the main mechanism of HELP.

Investigation of the Micromechanical Behavior of a Ti68Nb7Ta3Zr4Mo18 (at.%) High-Entropy Alloy.

Intense research efforts are focused on the development of advanced high-entropy alloys intended for premium aerospace components and other applications, where high strength and good formability are crucial. The mechanical properties of these alloys are closely related to the phase transformation, dislocation evolution, and grain size, and these factors are affected by the deformation temperature. The response of the retained austenite to strain-induced martensitic transformation at various temperatures was studied in an advanced Ti68Nb7Ta3Zr4Mo18 (at.%) high-entropy alloy via molecular dynamics simulation. It was found that the Ti68Nb7Ta3Zr4Mo18 alloy changes from a single crystal to a polycrystal during the tensile process, and the transition of the Ti68Nb7Ta3Zr4Mo18 (at.%) high-entropy alloy from the BCC phase to the FCC phase occurs. At high temperatures and low strain rates, grain boundary slip is the main deformation mechanism, and at low temperatures and high strain rates, dislocation slip replaces grain boundary slip as the dominant deformation mechanism, which improves the strength of the alloy. Moreover, when the grain size is too small, the strength of the alloy decreases, which does not satisfy the fine grain strengthening theory and shows an inverse Hall-Petch relationship. This study offers a new compositional window for the additive manufactured lightweight high-strength material categories for various applications including the aerospace industry.

Nano-cutting deformation characteristics and atomic-scale behavior of two-phase γ/γ′ nickel-based single crystal superalloy

The γ/γ′ interface has an important influence on the nanoscale deformation of nickel-based single crystal superalloy. In this paper, nano-cutting simulations of nickel-based single crystal superalloy are performed by molecular dynamics methods, and the mechanical properties, atomic displacements, dislocation evolution, temperature, surface quality and Al atom precipitation behavior of the workpiece are analyzed in depth. We found that: the γ/γ′ interface will hinder the force conduction and dislocation development, resulting in fluctuation of processing force and dislocation density. In addition, the special two-phase structure will affect the deformation of the material, and the dislocation motion will stay in the γ phase for a long time and occur dislocation accumulation and work hardening, meanwhile, there are more displacement atoms in the γ phase than in the γ′ phase, and the degree of plastic deformation in the γ phase will be more drastic. It is also found that there is always a difference in the temperature distribution of the two phases of the material, and the uneven cutting surface always appears at the junction of the two phases, and the Al atoms on the subsurface will precipitate and form an Al film covering the surface after being influenced by the cutting temperature.

Effect of temperature field on microstructural stability of Al–Cu–Mg alloy hemispherical component

Al–Cu–Mg alloy hemispherical components can be widely utilized in gyroscope navigation systems by virtue of low density, high deformability and fatigue strength. However, the nonuniformity in residual stress and microstructure of the component after deep drawing may lead to a complex microstructural evolution under the temperature environment, thereby decreasing the navigation precision. In this work, the evolution of grain sizes, dislocations, second phases and mechanical properties of Al–Cu–Mg alloy hemispherical components were evaluated under a temperature field. From the edge to the central part of the component, the grain size first decreased and then increased, while the hardness and residual stress first increased and then decreased. With the extension of exposure time, the dislocation density decreased and the coarsened Al2CuMg phases appeared, while the grain size of the component remained stable. Furthermore, the dislocation density declined faster and Al2CuMg phases precipitated rapider in the die fillet area in comparison with the situation at the bottom of the hemisphere. The higher dislocation density could provide more nucleation sites for Al2CuMg phases. Thereafter, more dislocations were consumed, thus accelerating the reduction of stored energy and lattice distortion under the temperature field. As a result, investigating the microstructural stability and mechanical properties of Al–Cu–Mg alloy hemispherical components can make a contribution to fabricating highly stabilized navigation devices to be further applied in the field of space exploration.

Investigating build orientation-induced mechanical anisotropy in additive manufacturing 316L stainless steel

Build orientation-induced mechanical anisotropy is critical for additive manufacturing metals. To leverage the existing research on anisotropy between Z and X/Y build orientations, this work focuses on the anisotropic behavior within 2D planes. Therefore, tensile coupons of 316L stainless steel (316L-SS) were fabricated in five different build orientations (X, Y, XY45°, Z, and ZX45°) using the laser powder bed fusion process with a pulsed laser. Different characterization techniques at various length scales were employed to investigate the mechanisms of mechanical anisotropy. According to the electron back-scattered diffraction (EBSD) study, X and Y samples had a larger fraction of <001> and <110> grains, whereas XY45° coupons had a larger fraction of <111> grains along the tensile axis. In contrast, Z samples exhibited a dominant <110> texture parallel to the tensile axis. X-ray diffraction analysis revealed that all the samples had a single austenitic phase but different dislocation densities. The tensile results of all samples showed higher yield strength and comparable ductility with those in the literature. Among all the build orientations, XY45° coupons had the highest yield strength due to the large fraction of <111> grains oriented along the tensile axis and the highest dislocation density of 2.2 × 1015 m−2. In contrast, the highest ductility of Z samples was caused due to twinning-favored <110> crystallographic texture along the tensile axis. The onset and termination of different stages of strain hardening were mainly affected by the cellular sub-grain structure and crystallographic texture, as well as their interactions with dislocation generation and evolution. These findings indicated that crystallographic texture and dislocation density were the dominant contributions to the mechanical anisotropy followed by grain morphology.

Nanoindentation study of δ-phase zirconium hydride using the crystal plasticity model

Zirconium hydride precipitation degrades the fracture toughness of nuclear reactor fuel cladding tube. Due to the difficulty of experiment, deep understanding on mechanical properties of zirconium hydride via numerical approaches is in a great need. To study the mechanical properties of zirconium hydride, the crystal plasticity finite element model considering geometrically necessary dislocations evolution is used to simulate the nanoindentation deformation behavior of single-crystal δ-hydride. The parameters in the crystal plasticity model are calibrated by Young's modulus along different crystallographic orientations and experimental stress-strain data at different strain rates. The predicted polycrystalline Young's modulus, Poisson's ratio, and nanoindentation hardness are in good agreement with the experimental results. The simulation results show that the nanoindentation hardness strongly depends on the indentation depth when it is smaller than 500 nm. Furthermore, the effects of crystallographic orientation and zirconium matrix on the indentation results are also studied. We find that the nanoindentation hardness of δ-hydride is slightly orientation dependent. For smaller hydride size or larger indentation depth, the surrounding zirconium matrix undergoes plastic deformation, which leads to a significant underestimate of the nanoindentation hardness of the hydride.

Dynamic recrystallization-dependent high-temperature tensile properties and deformation mechanisms in Al-Mg-Sc-Zr alloys

This research elucidates discontinuous dynamic recrystallization (DDRX)-dependent high-temperature tensile properties and deformation mechanisms in simply extruded Al-7Mg alloys tailored by Sc/Zr ratios. The bimodal-grained Al-7Mg-0.4Sc alloy presents a high elongation to failure of ∼540% at 400 °C and 5 × 10−4 s−1. However, such superplastic behavior has not been observed in both coarse-grained Al-7Mg-0.1Sc-0.3Zr and Al-7Mg-0.3Sc-0.1Zr alloys. Thermally stable dispersed nano-sized Al3(Sc,Zr) particles strongly retard DDRX, accompanied by the retention of heterogeneous grain structure in Al-7Mg-0.1Sc-0.3Zr till fracture. The predominance of dislocation slip is proved by analyzing the evolution of texture and dislocations. In contrast, the bimodal grain structure evolves into a homogeneous fine one in Al-7Mg-0.4Sc with tensile deformation proceeding since coarsening Al3Sc precipitates play a weak role in restricting DDRX. The superplasticity in Al-7Mg-0.4Sc is achieved by cooperated mechanisms, i.e., grain boundary sliding (GBS) and dislocation slip as dominant mechanisms, which is accommodated by DDRX in the initial tensile deformation stage, followed by dislocation slip-accommodated GBS in the late stage.

Phase Transformation Behaviors and Dislocation Evolutions of an Additively Manufactured Ti-6Al-4V Alloy under Annealing Treatment

Post annealing treatment is generally needed for additively manufactured titanium alloy to decompose metastable phases, alleviate residual stress, and improve ductility. In this work, in-situ electrical resistivity and line profile analysis of X-ray diffraction were utilized for monitoring phase transformation behaviors and dislocation evolutions of a laser powder bed fusion-built Ti-6Al-4V alloy under post annealing treatment. Besides, hardness and tensile tests were adopted for revealing the effects of phase transformation and dislocation evolutions on the mechanical properties. The results indicated that post annealing treatment decomposed martensitic α′ into lamellar α + β and eliminated dislocations efficiently. The martensite decomposition rate increased with the annealing temperature. Annealing at 700 °C for 4 h eliminated 98% of the dislocations, and further annealing has only a limited influence on the dislocation density. Annealing at 700 °C for 16 h is beneficial for achieving a high ductility of 10.3% owing to the favorable equilibrium lamellar α + β microstructure. These findings provide valuable insights for optimizing post annealing treatment procedures to enhance the mechanical properties of additively manufactured Ti-6Al-4V alloys.

Multi-hazard socio-physical resilience assessment of hurricane-induced hazards on coastal communities

Hurricane-induced hazards can result in significant damage to the built environment cascading into major impacts to the households, social institutions, and local economy. Although quantifying physical impacts of hurricane-induced hazards is essential for risk analysis, it is necessary but not sufficient for community resilience planning. While there have been several studies on hurricane risk and recovery assessment at the building- and community-level, few studies have focused on the nexus of coupled physical and social disruptions, particularly when characterizing recovery in the face of coastal multi-hazards. Therefore, this study presents an integrated approach to quantify the socio-physical disruption following hurricane-induced multi-hazards (e.g., wind, storm surge, wave) by considering the physical damage and functionality of the built environment along with the population dynamics over time. Specifically, high-resolution fragility models of buildings, and power and transportation infrastructures capture the combined impacts of hurricane loading on the built environment. Beyond simulating recovery by tracking infrastructure network performance metrics, such as access to essential facilities, this coupled socio-physical approach affords projection of post-hazard population dislocation and temporal evolution of housing and household recovery constrained by the building and infrastructure recovery. The results reveal the relative importance of multi-hazard consideration in the damage and recovery assessment of communities, along with the role of interdependent socio-physical system modeling when evaluating metrics such as housing recovery or the need for emergency shelter. Furthermore, the methodology presented here provides a foundation for resilience-informed decisions for coastal communities.

Can electric heating replace contact heating in high-temperature test for nickel base single crystal superalloy?

Compared with contact heating or environmental heating in high-temperature test, electric heating has the advantage that it can realize in-situ high-temperature heating in SEM. Especially, it can simplify the heating and loading equipment and clearly obtain surface microstructure information of small scale specimens. However, due to the positive feedback characteristic of Joule thermal effect and other electro-induced effects in materials, such as the influence of electromigration and electric field on dislocation motion, etc. the effectiveness of high temperature mechanical properties of materials obtained under electric heating needs further study. In this paper, the tensile properties of nickel-based single crystal superalloy at room temperature to 950 ℃ were conducted using by electric heating and contact heating modes. The results show that when the heating temperature is below 600 ℃, the fracture mode and dislocation evolution of nickel base single crystal superalloy do not change significantly under two heating modes; When the heating temperature exceeds 600 ℃, the macroscopic mechanical properties change gradually, but the elastic modulus has no obvious difference. Through the distribution of two-phase elements, it is found that the relevant differences are mainly related to element migration. In addition to the thermal effect caused by electric current, the athermal effect promotes dislocation movement and element migration, which leads to the increasing difference of mechanical properties at high temperature under the two heating modes. These results show that at the temperature exceeds 600 ℃, the electric heating method is no longer suitable for studying the high-temperature mechanical properties of nickel-based single crystal superalloy.