Spherical Precipitates Research Articles

Strengthening via Orowan Looping of Misfitting Plate-like Precipitates

Many common engineering alloys are strengthened by precipitates with plate-like geometries. The mechanics of precipitation strengthening, while well resolved with spherical precipitates, are less well understood for plate-like geometries. In this work, we employ discrete dislocation dynamics simulations to study precipitation strengthening by θ′ precipitates in AlCu. We show that Orowan looping with parallel plate-like precipitates can be fundamentally different from spheres because it is governed by a steady-state glide process rather than a single critical dislocation geometry. We develop a model based on the formation of a dislocation dipole across the precipitate thickness to explain the observed strengthening. Finally, we show that while the precipitate misfit field can lead to both strengthening and weakening, strengthening is more common because of the steady-state process by which Orowan loops form.

Микроструктура и свойства сплава Zn–1%Li–2%Mg, подвергнутого интенсивной пластической деформации

In this paper, the authors consider the mechanisms of formation of high-strength states in the Zn–1%Li–2%Mg alloy as a result of its processing by the high pressure torsion (HPT) method. For the first time, the study showed that using HPT treatment, as a result of varying the degree of deformation at room temperature, it is possible to increase the ultimate strength of a zinc alloy from 155 to 383 MPa (with an increase in the yield stress from 149 to 306 MPa) without losing its ductility. To explain the reasons for the increase in the zinc alloy mechanical properties, its microstructure was analyzed by scanning electron microscopy (SEM), X-ray phase analysis (XPA), X-ray diffraction analysis (XRD), and small-angle X-ray scattering (SAXS). Using XPA, the authors established for the first time that Zn(eutectic)+β-LiZn4(eutectic)→~LiZn3+Zn(phase)+Zn(precipitation) and MgZn2→Mg2Zn11 phase transformations occur in the zinc alloy during HPT treatment. SEM analysis showed that at the initial stages of HPT treatment, cylindrical Zn particles with a diameter of 330 nm and a length of up to 950 nm precipitate in β-LiZn3 phase. At the same time, the SAXS method showed that needle-like LiZn4 particles with a diameter of 9 nm and a length of 28 nm precipitate in the Zn phase. The study established that, only spherical Zn and LiZn4 particles precipitate at high degrees of HPT treatment. Precision analysis of the zinc alloy microstructure showed that HPT treatment leads to grain refinement, an increase in the magnitude of crystal lattice microdistortion, a growth of the density of dislocations, which are predominantly of the edge type. As a result of the analysis of hardening mechanisms, the authors concluded that the increase in the zinc alloy strength characteristics mainly occurs due to grain-boundary, dislocation, and dispersion hardening.

Microstructure and Mechanical Properties of Selective Laser Melted Reduced Activation Ferritic/Martensitic Steel

Cube and tensile samples of reduced activation ferritic/martensitic steel were formed at different laser powers and scanning velocities using a selective laser melting process; the microstructural characteristics and tensile properties of the cube and tensile samples were investigated in this study. The experimental results showed that the SLMed CLF-1 samples that formed with selected laser melting were near-fully dense, and the relative density of the SLMed CLF-1 samples exceeded 99%. Meanwhile, there were numerous nano-sized spherical and needle-like precipitate dispersions distributed in the grains and boundary of the grains, and the precipitates were mainly composed of M23C6 carbide and MX carbide. The microstructure was composed of columnar grains and equiaxed grains arranged in a sequence, and the smallest average size of the grains was 15 ± 2.1 µm when measured at 320 W of power and 800 mm/s scanning velocity. In addition, the sample at 320 W of power and 800 mm/s scanning velocity exhibited higher yield strength (875 ± 6.0 MPa) and higher elongation (25.6 ± 0.8%) than that of the sample at 200 W of power, 800 mm/s scanning velocity, yield strength of 715 ± 1.5 MPa, and elongation of 22.6 ± 1.2%.

Effect of a special thermo-mechanical treatment process on microstructure and properties of 7185 alloy

A special thermo-mechanical treatment (ST) process involving two stages of deformation was studied, and the influence mechanism for the first stage of deformation (pre-deformation) on the microstructure evolution and properties of 7185 alloy was researched in detail. The results showed that increasing the amount of pre-deformation could increase the number of spherical precipitates, significantly increase the dislocation density, and form dislocation walls and dislocation cells. The medium-temperature precipitation (MTP) could transform the high-density dislocation cells into ordered dislocation arrays and form many substructures and sub-crystals. After the second stage of deformation (final hot rolling, FHR), the number of precipitates increased again. The sub-crystals were regularly arranged and microscopic shear bands formed. With a weakening of the pinning force, the boundary of the banded microstructure composed of high-density dislocations became straighter. After solution treatment, the movement of low angle grain boundaries (LAGBs) and sub-grain boundaries was blocked due to particle pinning and accumulated strain, which significantly promoted the transition from LAGBs to high angle grain boundaries, thus achieving grain refinement. Therefore, the maximum pre-deformation process (ST3: pre-deformation (250 °C, 60%) + MTP (400 °C, 40 min) + FHR (400 °C, 50%)) could significantly improve the plasticity and corrosion resistance of 7185 alloys.

Microstructural and residual stress analysis of functionally graded friction surfaced Al-Cu-Mg-Ag alloy

This study analyzed the microstructure and residual stress of a functionally graded friction surfaced Al-Cu-Mg-Ag alloy. To prepare a multilayer material using the friction surfacing process, different layers of Al-Cu-Mg alloy containing 3, 7, and 12 wt% of silver powder were deposited on the Al-Cu-Mg alloy substrate. After homogenization and aging heat treatment, a functionally graded structure with different silver weight percentages in different layers was obtained. The results showed that silver powder reduces the dimensions of the clad layers compared to the sample without silver. After homogenization and artificial aging treatment, a bimodal microstructure formed in the silver-containing sample. It was determined that two types of spherical (S-Al 2 CuMg) and rod-shaped precipitates (Ω precipitates) are formed in the microstructure of different layers. By moving from the first layer to the third layer, the concentration of Ω precipitates increases as the weight percentage of silver added to the microstructure increases. After aging heat treatment, it is observed that the hardness changes are mild, and the average hardness increases from the substrate (134 HV0.1) to the third layer (165 HV0.1).

Manipulation of mechanical properties of 7xxx aluminum alloy via a hybrid approach of machine learning and key experiments

Considering the complex relationship among mechanical properties of 7xxx aluminum alloy, it is very crucial to optimize two or more target properties simultaneously in developing new materials. In this paper, three different machine learning assisted strategies are used to study the relationship between alloy composition, process parameters and mechanical properties of 7xxx aluminum alloy, which is expected to accelerate the development of new materials. Firstly, the mechanical properties prediction model of 7xxx aluminum alloy was established by back propagation (BP) neural network. Then, on this basis, genetic algorithm (GA) is used to optimize the prediction accuracy of back propagation (BP) neural network. In addition, a radial basis function (RBF) neural network is used for modeling analysis, and the prediction results of the three models are compared. The results show that back propagation (BP) neural network optimized by genetic algorithm (BP-GA) has higher prediction accuracy than BP and RBF neural network, the coefficient of correlation (R), average absolute relative error (AARE) and root mean squared error (RMSE) value are 0.948, 4.28%, 0.087, respectively. In addition, scanning electron microscope (SEM), electron backscatter diffraction (EBSD), high resolution transmission electron microscope (HRTEM) and the tensile test were used to carry out the related experimental verification work. A large number of fine and dispersed spherical precipitates can be observed after ageing heat treatment. The experimental value is close to the target value, which further confirms that BP neural network model optimized by genetic algorithm can be used to predict and design 7xxx aluminum alloy.

Effects of rolling deformation on precipitation behavior and mechanical properties of Al–Zn–Mg–Cu alloy

The effects of cold rolling (CR) with different hot rolling (HR) reductions on the precipitation behavior and mechanical properties of Al–Zn–Mg–Cu (AA7050) alloy are investigated by synchrotron small angle X-ray scattering (SAXS) and transmission electron microscope (TEM). With increasing HR reduction, the refinement degree of recrystallized structure increases, the dissolution and fragmentation of the second phase particles, and ultrafine sub-grains in shear bands occur. The number of spherical strain-induced precipitates (SIP) and ultrafine sub-grains increase due to high dislocation density before T6 heat treatment. After T6 heat treatment, the morphology of nanoprecipitates changes from rod-like to globular, the mean size of nanoprecipitates decreases, and the volume fraction increases with growing HR reduction. The 7050 alloy with 80 % HR reduction presents the highest yield strength of ∼513 MPa, the tensile strength of ∼571 MPa and elongation of ∼13.6 %. The strength increment is mainly ascribed to the contribution of precipitation strengthening and dislocation strengthening relevant to the small mean size and large volume fraction of nanoprecipitates. The improved ductility attributes to the refined recrystallized structure and multi-scale and multi-morphology particles. This investigation can guide further designing novel aluminum alloys by tailoring refined grain, highly dispersed nanoprecipitate structures for a preeminent combination of mechanical properties.

A combinatorial assessment of microstructure and mechanical properties in AlCrCuFeNi2Vx concentrated alloys

This study developed a novel series of AlCrCuFeNi2Vx (x = 0, 0.3 and 0.6) high-entropy alloys (HEAs), and systemically assessed the relationship between composition, processing, microstructure and mechanical properties. The alloys were produced by arc melting and studied in as-solidified and homogenized (annealing at 650 ℃ for 4 h) conditions. In the base alloy of AlCrCuFeNi2, the microstructure consists of disordered bcc and fcc phases, ordered B2 and L12 phases, and the B2 phase and bcc phase are coherent. With the increase of V content, the volume fraction of bcc/B2 phases increase, accompanied with a peculiar phenomenon that the shape of B2 phase has transferred from irregular matrix to spherical precipitates, which caused by the increase of lattice misfit after V addition. Moreover, a large number of Cu particles are randomly distributed in the NiAl (B2) phase, and the crystal structure of Cu particles has changed from 9 R structure to fcc structure after annealing treatment. Mechanical tests of these alloys reveal that the 0.6 at% V addition has doubled the yield strength (V0, 780 MPa; V0.6, 1673 MPa) for the increase in volume fraction of bcc/B2 phase and the solid solution strengthening produces by V addition. The yield strength is increased by 124 MPa after annealing treatment in V0.6 alloy without sacrificing the ductility due to the promotion of L12 phase after annealing treatment.

Effect of Microstructure on High Cycle Fatigue Behavior of 211Z.X-T6 Aluminum Alloy

In the present paper, the high cycle fatigue (HCF) of a novel 211Z.X aluminum alloy with high strength was studied under hot-rolling and as-cast states at room temperature. The effects of microstructure and distribution of precipitated phases and impurities on the mechanical properties, HCF performances, fatigue microcrack initiation, and propagation behavior of the 211Z.X alloy were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The HCF S–N curves, P–S–N curves and Goodman fatigue diagrams of 211Z.X alloy consisting of two microstructures were drawn. The results suggested that the fine and dispersive distribution of the second phases improved the strength of the alloy. The formation of short-bar and spherical precipitates promoted coordinated deformation of the alloy. This promoted higher microcrack initiation resistance of 211Z.X alloy with a hot rolling state than in the cast state. As a result, the HCF properties of the hot-rolling alloy were better than those of the cast alloy. In sum, these results look promising for future reliable design of engineering structures and application of new aluminum alloys.

The effect of Al/Ti ratio on the evolution of precipitates and their effects on mechanical properties for Ni35(CoCrFe)55AlxTi10−x high entropy alloys

L12-structured Ni3(Al, Ti) precipitates are promising strengthening particles in face-centered-cubic high entropy alloys (HEAs). However, if the Al/Ti ratio (R) is not carefully controlled, brittle intermetallic compounds can form, especially at the grain boundaries (GBs). In this study, a series of Ni35(CoCrFe)55AlxTi10−x HEAs with different R values, R = x/(10-x), were prepared, and the evolution of precipitates and their effects on the mechanical properties were investigated. The dispersed spherical precipitates within the grains act as an effective barrier to dislocation slip, producing high strength. However, increasing R (increasing Al) reduces the volume fraction of the precipitates within the grains, resulting in a decrease of yield strength. Both experimental measurements and first-principles calculations show that Al, Ti and Ni segregate to the GBs. This leads to the formation of L12 precipitates at the GB that, upon aging, coarsen to layer-like structures. When R ≥ 3 the local supersaturation of Al and Ti also leads to formation of a Heusler phase at the GBs, which reduces the ductility. However, when R > 3.5 the volume fraction of the Heusler phase decreases, and the plasticity increases again. These findings provide important guidance and inspire new strategies for the microstructural control in precipitate-strengthened HEAs.

Partitionless solidification and anomalous triradiate crystal formation in drop-tube processed Al-3.9 wt%Fe alloys

Drop tube atomized Al-3.9 wt% Fe alloy has been investigated. Spherical samples were collected and sieved into 9 different size fractions ranging between 850 + µm to 38 µm, with corresponding estimated cooling rates ranging between 100 and 20,000 K s−1. X-ray diffraction analysis showed the presence of Al, Al13Fe4 and Al6Fe in all size fractions. Scanning electron microscopy and optical microscopy have been employed for microstructural evolution. Large proeutectic crystals of Al13Fe4 surrounded by α-Al, dendritic α-Al with interdendritic lamellar eutectic, lamellar eutectic and rod-like eutectic was observed in samples with d > 212 µm. In the smaller samples (d < 212 µm) primary Al13Fe4 disappeared and featureless Y-shaped structures with thin, triradiating arms start to emerge. These Y-shaped structures can be heavily fragmented in nature and appear to be the first phase to nucleate in the droplets, followed by divorced eutectic, microcellular α-Al, dendritic α-Al with lamellar interdendritic eutectic and lamellar and rod-like eutectics. Serial sectioning with a cumulative depth of 20.2 µm has revealed that the Y-shaped features have an internally connected sheet-like morphology. Transmission electron microscopy reveals that these Y-shaped features are composed of nano-sized needle-like and spherical precipitates. TEM diffraction from a Y-shaped region has revealed the presence of AlmFe in this region. EDX analysis shows that these Y-shaped features have the same bulk composition as the liquid from which they grew, suggesting they form via partitionless solidification of highly supersaturated α-Al, which subsequently undergoes solid-state decomposition. The formation of these feature also slightly increases the eutectic spacing from 0.35 µm in the 300–212 µm size fraction to 0.45 µm in the 212–150 µm size fraction. In order to understand the effect of nonequilibrium the solidification on the mechanical properties microhardness of the droplets was measured. The microhardness has risen from 50 HV0.01 to 83 HV0.01 for 850+µm and 53≤d≤38µm droplets respectively.

A generalized line tension model for precipitate strengthening in metallic alloys

A generalized line tension model has been developed to estimate the critical resolved shear stress in precipitation hardened alloys. The model is based in previous line tension models for regular arrays of either impenetrable or shearable spherical precipitates that were expanded to take into account the effect of the elastic mismatch between the matrix and the precipitates. The model parameters are calibrated from dislocation dynamics simulations that covered a wide range of precipitate diameters and spacing as well as of the mismatch in elastic constants. This model is extended to deal with random arrays of monodisperse spherical precipitates by changing the geometrical parameters of the model by the averaged ones corresponding to the random distributions. The model predictions were in good agreement with the critical resolved shear stresses obtained from dislocation dynamics simulations of random spherical precipitates distributions for both impenetrable and shearable precipitates, providing a fast and accurate tool to predict precipitate strengthening in metallic alloys.

Coarsening kinetics of Cu particles in an Fe-1.5% Cu alloy

Abstract The Ostwald ripening of spherical and rod-shaped Cu precipitate particles in an Fe-1.5 mass% Cu alloy aged between 873 and 1023 K has been examined by measuring both the particle size by electron microscopy and the Cu concentration in the α-Fe matrix by electrical resistivity. The average radius of spherical and rod-shaped particles increases with ageing time t as t 1/3, in agreement with the growth by diffusion-controlled coarsening. The kinetics of the depletion of supersaturation with t obey the predicted t – 1/3 time law. The Cu/α-Fe interfacial energy and the diffusivity of Cu in α-Fe have been independently derived from the data on coarsening. The interfacial energies are measured as 0.57 and 1.1 Jm–2 for the spherical and rod-shaped particles respectively. The pre-exponential factor and the activation energy for bulk diffusion are found to be 4.54α10 –5 m2s– 1 and 241 kJmol – 1.

Heterogeneous precipitation strengthened non-equiatomic NiCoFeAlTi medium entropy alloy with excellent mechanical properties

The outstanding strength-ductility combination has always been a challenging problem in the development of metal materials, high entropy alloys/medium entropy alloys (HEAs/MEAs) are considered to be the key material to solve this problem. Here a novel non-equiatomic Ni46Co24Fe24Al3Ti3 MEA with equiaxed grains was prepared by vacuum suspension melting, which consists of FCC matrix and heterogeneous L12 precipitate. In the current work, the different states of the Ni46Co24Fe24Al3Ti3 MEA from as-cast to after thermo-mechanical processing (TMP) were systematically researched. The result shows that the heterogeneous L12 precipitate of the as-cast alloy is composed of cubic precipitates at the grain boundary and spherical precipitates in the grain interior. After TMP, a short-rod L12 precipitated by discontinuous precipitation reaction (DP) at the grain boundary, and a spherical L12 precipitated by continuous precipitation reaction (CP) in the grain interior. Meanwhile, the alloy shows outstanding mechanical properties in the tensile test at room temperature. The ultimate tensile strength of the as-cast alloy is 935 MPa, with an elongation of 32%. The strength of the alloy is further improved after TMP, the yield strength and ultimate tensile strength are respectively 820 MPa and 1236 MPa, with an elongation of 23% retained. Compared with the single-phase NiCoFe MEA, the yield strength and ultimate tensile strength are significantly increased by 310％ and 147％. The excellent mechanical properties of the alloy are attributed to the combination of the soft FCC matrix and the strengthening of the L12 precipitate.

Strain and interface energy of ellipsoidal inclusions subjected to volumetric eigenstrains: shape factors

Thermodynamic modeling of the development of non-spherical inclusions as precipitates in alloys is an important topic in computational materials science. The precipitates may have markedly different properties compared to the matrix. Both the elastic contrast and the misfit eigenstrain may yield a remarkable generation of elastic strain energy which immediately influences the kinetics of the developing precipitates. The relevant thermodynamic framework has been mostly based on spherical precipitates. However, the shapes of actual particles are often not spherical. The energetics of such precipitates can be met by adapting the spherical energy terms with shape factors. The well-established Eshelby framework is used to evaluate the elastic strain energy of inclusions with ellipsoidal shapes (described by the axes a, b, and c) that are subjected to a volumetric transformation strain. The outcome of the study is two shape factors, one for the elastic strain energy and the other for the interface energy. Both quantities are provided in the form of easy-to-use diagrams. Furthermore, threshold elastic contrasts yielding strain energy shape factors with the value 1.0 for any ellipsoidal shape are studied.

Precipitation behaviors and mechanical properties of a solution-treated Mg-Gd-Nd-Zn-Zr alloy during equal-channel angular pressing process

A magnesium alloy processed by equal-channel angular pressing (ECAP) exhibited excellent microstructure refinement and improved strength and hardness. The comprehensive mechanical properties of magnesium alloys have supported the expansion of their applications in the automotive, aerospace, and biomedical industries. Herein, pre-treatment of a solution-treated Mg-2.9Gd-1.5Nd-0.3Zn-0.3Zr alloy was conducted to investigate the precipitate behavior and microstructure evolution during the ECAP process. β 1 phase grains quickly precipitated from the solution-treated alloy, which accelerated grain refinement and enhanced the ductility after the ECAP process, as compared to the as-cast alloy reported in our previous study. Moreover, spherical precipitates (∼200 nm) and fine phases (∼100 nm) precipitated along the stripe-like Zn 2 Zr 3 phase, which formed a kabap-like structure dispersing homogeneously in the solution-treated alloy during the ECAP process. Owing to grain refinement, dislocations, spherical β 1 precipitates, and texture evolution, the solution-treated alloy after eight passes of ECAP exhibited good comprehensive mechanical properties, with the ultimate tensile strength, yield strength, and elongation values reaching 210.9 MPa, 263.9 MPa, and 27.9%, respectively.

The microstructure and mechanical properties of the additive manufactured AlCoCrFeNi high entropy alloy

The equimolar AlCoCrFeNi high entropy alloy (HEA) was successfully fabricated by direct energy deposition (DED), and its phase composition, microstructure and mechanical properties were discussed systematically. The DED samples showed a duplex BCC crystal structure, which is consistent with the original powder state. The microstructure of the DED samples transferred from columnar grain structure into equiaxed dendritic structure along building direction from bottom to top. What's more, the crystallographic orientation in different positions of the DED samples showed an apparent difference. The columnar grain structure presented a strong texture in building direction at the bottom, while equiaxed dendritic structure exhibited random crystallographic orientations at the top. The equiaxed dendrites structure in the DED samples is comprised of dendrites (DR) and interdendrites (ID) regions due to elemental segregation. Meanwhile, the fine microstructure of DR and ID regions is discovered to be nano-sized spherical precipitates morphology and weave-like morphology, respectively. Furthermore, compared with AlCoCrFeNi HEA produced by conventional casting method, the mechanical properties of the DED samples display a superior combination of strength and ductility. Therefore, this research could provide an effective theoretical guidance for the preparation of high strength-ductility of HEAs.

Cementite decomposition in 100Cr6 bearing steel during high-pressure torsion: Influence of precipitate composition, size, morphology and matrix hardness

Premature failure of rail and bearing steels by White-Etching-Cracks leads to severe economic losses. This failure mechanism is associated with microstructure decomposition via local severe plastic deformation. The decomposition of cementite plays a key role. Due to the high hardness of this phase, it is the most difficult obstacle to overcome in the decaying microstructure. Understanding the mechanisms of carbide decomposition is essential for designing damage-resistant steels for industrial applications.We investigate cementite decomposition in the bearing steel 100Cr6 (AISI 52100) upon exposure to high-pressure torsion (maximum shear strain, Ƴmax = 50.2). Following-up on our earlier work on cementite decomposition in hardened 100Cr6 steel (Qin et al., Act. Mater. 2020 [1]), we now apply a modified heat treatment to generate a soft-annealed microstructure where spherical and lamellar cementite precipitates are embedded in a ferritic matrix. These two precipitate types differ in morphology (spherical vs. lamellar), size (spherical: 100–1000 nm diameter, lamellar: 40–100 nm thickness) and composition (Cr and Mn partitioning). We unravel the correlation between cementite type and its resistance to decomposition using multi-scale chemical and structural characterization techniques.Upon high-pressure torsion, the spherical cementite precipitates did not decompose, but the larger spherical precipitates (≥ 1 μm) deformed. In contrast, the lamellar cementite precipitates underwent thinning followed by decomposition and dissolution. Moreover, the decomposition behavior of cementite precipitates is affected by the type of matrix microstructure. We conclude that the cementite size and morphology, as well as the matrix mechanical properties are the predominating factors influencing the decomposition behavior of cementite. The compositional effects of Cr and Mn on cementite stability calculated by complementary density functional theory (DFT) calculations are minor in the current scenario.

MD simulation of interactions of atomic displacement cascades with β-Nb precipitates in a zirconium matrix

In this work, we investigated the effect of spherical binary precipitates and needle-shaped nanoparticles of β-Nb on the evolution of cascade processes in the Zr matrix using the method of molecular dynamics and many-body interatomic potentials. For a case of spherical precipitates, the formation of the interphase region with length of ~ 10 Å was observed. The fraction of the Zr atoms in the precipitate increased during the cascade processes. The Nb atoms, which were initially inside the precipitate, did not leave the boundaries of the interphase region after relaxation of the model crystallite. After the cascade process, the Nb atoms were detected Zr matrix at a distance of no more than 5 Å from interphase boundary. Point defects, as well as their clusters, are formed mainly near the surface of the precipitate. In a case of needle-shaped nanoparticles, a slight “blurring” of the particle boundaries with an increase in the number of niobium atoms in the near- boundary region were observed. After the atomic displacement cascade, part of the niobium atoms moved from nanoparticle into the near-boundary region. Only a few niobium atoms moved into the α-phase matrix outside the near-boundary region. No cases of significant dissolution of the nanoparticle were observed. We also observed the formation of clusters consisting of a mixture of vacancies and SIAs in the structure of the nanoparticle.

Dislocation Topological Evolution and Energy Analysis in Misfit Hardening of Spherical Precipitate by the Parametric Dislocation Dynamics Simulation.

Interaction of a single dislocation line and a misfit spherical precipitate has been simulated by the Parametric Dislocation Dynamics (PDD) method in this research. The internal stress inside the precipitate is deduced from Eshelby’s inclusion theory, the stress of the dislocation line and outside the precipitate is calculated by Green’s function. The influence of different relative heights of the primary slip plane on dislocation evolution is investigated, while the cross-slip mechanism and annihilation reaction are considered. The simulation results show three kinds of dislocation topological evolution: loop-forming (Orowan loop or prismatic loop), helix-forming, and gradual unpinning. The dislocation nodal force and the velocity vectors are visualized to study dislocation motion tendency. According to the stress–strain curve and the energy curves associated with the dislocation motion, the pinning stress level is strongly influenced by the topological change of dislocation as well as the relative heights of the primary slip plane.