Microstructural Defects Research Articles

A Study on Microstructure and Properties of Aluminum Alloy Bracket Produced by a New Semi-Solid Rheo-Diecasting Process

The performance of bracket component is low with uneven micro-structure, internal porosity and shrinkage defects produced by traditional liquid die casting process which cannot be strengthened by T6 heat treatment. In this paper, the aluminum alloy bracket with high-performance and light weight was prepared by a novel semi-solid slurry preparation technique that included chilling rod stirring and funnel-shaped cylinder device, which rapidly reducing the liquid temperature to near liquidus and realizing explosive nucleation. The effects of pouring temperature and CRS process on the microstructure and mechanical property of bracket were studied by optical microscopy (OM) equipped with polarizing mode and bench failure test. The results show that the as-cast microstructure mainly consists of near-spherical α-Al. And the semi-solid micro-structure was affected by these two critical parameters, the pouring temperature and CRS process. Without the condition of stirring, the micro-structure is typical dendritic with a certain proportion of fine spherical crystals, which was mainly generated during the filling of die casting process. And with the addition of the chilling rod, the finer and more uniform spherical semi-solid micro-structure was obtained with the lower pouring temperature. Based on the above semi-solid process and flow controlling through the mould design and vertical die casting process optimization, the high-performance bracket component without shrinkage can be prepared. Additionally, compared with the liquid die casting process, the internal quality and bench testing force of bracket prepared by CRS vertical die casting process are significantly improved.

(Invited) Application of Synchrotron X-Ray Topography Techniques to the Analysis of Defect Microstructures in Bulk GaN Substrates and Epilayers for Power Devices

Wide bandgap semiconductor gallium nitride (GaN), along with silicon carbide (SiC) are replacing silicon materials in the applications for power electronic devices. While SiC-based power technologies are based on bulk SiC substrates, GaN-based power technologies have until recently been based on GaN layers grown on foreign substrates such as sapphire, SiC and Si substrates. To achieve the full potential of GaN power devices, devices on bulk GaN substrates are desirable. In this review, the use of synchrotron X-ray topography techniques to evaluate defects and strain in bulk GaN substrates for vertical device development is presented. Ray tracing simulations is shown to effectively identify the Burgers vectors of all dislocations on X-ray topographs from GaN materials. Ammonothermal-grown GaN substrate wafers show the best quality among all the wafers. These wafers, which are free of basal plane dislocations (BPDs), have low curvature and threading mixed dislocations (TMDs) dominant among the TDs. However, certain ammonothermal substrates contain growth sectors with different impurity concentrations that are likely inherited from prior seed expansion growth runs. Patterned hydride vapor phase epitaxy (HVPE) GaN reveal a starkly heterogeneous distribution of dislocations with large areas containing low threading dislocation densities in between a grid of strain centers with higher threading dislocation densities and BPDs. These substrates also contain growth sector boundaries separating core regions growing in <11-22> directions and surrounding regions growing along [0001]. HVPE GaN substrates are characterized by high lattice distortion and dislocation densities of the order of 105-106 cm-2, which is much higher than 103-104 cm-2 of ammonothermal samples and dislocation-free areas in the patterned HVPE samples. Epitaxial growth and other processes involving heat treatment (including annealing) does not nucleate new defects but can result in interactions of dislocations (threading screw dislocations(TSDs)/threading mixed dislocations (TMDs)/threading edge dislocations (TEDs)) with point defects leading to changes in dislocation configurations. Mg-ion implantation for p-type doping does not change the distribution of dislocation but introduces lattice damage. By Rocking curve Analysis by Dynamical Simulation (RADS) analysis of X-ray rocking curves, the depth profile of strain can be obtained and correlated with doping profile. During annealing the implanted samples to heal lattice damage and activate the Mg ions, proper capping is necessary to limit loss of matter and introduction of additional lattice distortion. However, high pressure annealing has been shown to eliminate the need for capping. The effect on microstructure from other selectively area doping techniques such as etch and regrowth, diffusion and neutron transmutation will also be discussed.

Finishing Additively Manufactured Ti6Al4V Alloy with Low-Energy Electrical Discharges.

Additive manufacturing has garnered significant interest in various industries due to its flexibility and capability to produce parts with complex shapes. However, issues related to surface quality, such as roughness and microstructural defects, necessitate the use of post-processing techniques to achieve the desired properties. Ti6Al4V alloy, produced additively, was finished using low-energy discharges, and the new surface integrity properties resulting from the induced heat energy were investigated. To further understand the influence of discharge energy on the formation of the new layer, roughness parameters and power spectral density were used to characterize the surface topography. SEM and EDS analyses were performed to examine the morphology and microstructural defects such as microcracks. The results indicate that the heat energy induced by the discharge improved the properties of the surface. SEM analysis revealed that the new layer was characterized by a reduction in defects such as unmelted particles, the balling effect, and microcracks. At the lowest investigated discharge energy of E = 0.21 mJ, surface roughness, Sa, was reduced by about 69%, which is equal to about 2 μm, accompanied by a significant decrease in microcracks. EDS analysis indicated that the diffusion of copper and zinc from the electrode to the top surface was related to the discharge energy. Furthermore, prediction models of the influence of wire electrical discharge polishing parameters, including discharge energy, wire speed, and time interval, on the surface roughness and material removal rate (MRR) were developed using the response surface methodology.

Microstructure Evolution and Recrystallization of Ti6246 Alloy in Hot‐Rolling and Annealing Processes

Herein, the Ti‐6Al‐2Sn‐4Zr‐6Mo (Ti6246)‐casted alloy is treated with two different hot‐rolling processes (3‐pass and 5‐pass), and the as‐rolled alloy is subsequently annealed at different temperatures (780 and 850 °C). During hot rolling, obvious changes in the morphology and microstructure of the Ti6246 alloy occur. A large number of dislocations are generated in the rolling process, and their movement plays an important role in the microstructure evolution of the alloy. The 3‐pass hot rolling results in a smaller grain size (0.43 μm) than that of the 5‐pass rolled sample (0.68 μm), which can be attributed to the larger deformation degree of the single pass in the 3‐pass rolling process. However, the larger deformation degree of the 3‐pass rolling leads to higher dislocation density (34.29% of LM above 1) and more microstructure defects in the Ti6246 alloy, which further result in easier initiation of the prismatic and pyramidal slips of the alloy. The 5‐pass procedure can provide more deformation passes to promote the dynamic recrystallization (DRX) of the Ti6246 alloy and the fraction of DRX can reach 33.27%. In contrast, with the increase of the annealing temperature, the degree of recrystallization increases and the number of microstructure defects decreases.

A Comparison of Microstructure and Casting Defects of Rheocasting and Thixocasting Al-Si-Mg Alloy

In this paper, both thixocasting and rheocasting of Al-7Si-0.6Mg alloy (EN AC 42200) for the same part was performed. It was found that rheocasting of Al-7Si-0.6Mg alloy show a smaller primary Al grain size and significant improvement of cast defects compared with thixocasting of Al-7Si-0.6Mg alloy. This paper demonstrates that rheocasting of Al-7Si-0.6Mg alloy is more beneficial in terms of microstructure and cast defects compared with thixocasting of Al-7Si-0.6Mg alloy.

Research on reaction characteristics and mechanisms of Al-ZnO system powder

The inadequate bonding strength between ceramic and steel and microstructure defects caused by heat dissipation make it difficult to enhance the composite's performance. Hence, the utilization of self-exothermic Al-ZnO system powder to increase the melt temperature and synthesize interfacial transition layers has emerged as a novel solution to change bonding interfaces. In this study, the reaction characteristics and mechanism were analyzed, as well as the influence of temperature, reaction atmosphere, weight ratio, and particle size on the Al-ZnO system powder. Additionally, the influence factor for the exothermic characteristic and the moderating method for the powder system were investigated. The main conclusions are that when the powder composition ratio is closer to the equilibrium stoichiometry and the particle size is larger, the self-exothermic reaction heat release decreases, the reaction stability improves, and the intermetallic reaction becomes more apparent. Moreover, no reaction is observed when Al particles beyond 40 μm. The reaction products are significantly influenced by different reaction atmosphere environments, while the reaction point remains less affected. The Al-ZnO system powder exhibits a wide moderating capability, with effective reaction point ranging from 599 °C to 1200 °C. Additionally, the reaction exotherm is adjustable between 200～1720 J/g.

The Effect of Microstructural Defects on High-Cycle Fatigue of Ti Grade 2 Manufactured by PBF-LB and Hydrostatic Extrusion

The aim of this study was to show the effect of manufacturing defects in a commercially pure Ti Grade 2 produced by a laser beam powder bed fusion (PBF-LB) process on its high-cycle fatigue life. For this purpose, the high-cycle fatigue performance of PBF-LB Ti Grade 2 was compared to its ultrafine-grained (UFG) counterpart processed by hydrostatic extrusion exhibiting a similar mechanical properties under static tensile. The yield strength of the PBF-LB and UFG Ti Grade 2 was 740 and 783 MPa, respectively. The PBF-LB Ti Grade 2 consisted of a typical columnar of prior β grains with an acicular martensite α’ microstructure, while UFG Ti Grade 2 was mainly composed of fine, equiaxed α phase grains/subgrains with a size of 50–150 nm. A residual porosity of 0.21% was observed in the PBF-LB Ti Grade 2 by X-ray computed tomography, and, despite similar yield strength, a significantly higher endurance fatigue limit was noticed for UFG Ti Grade 2 (420 MPa) compared to PBF-LB Ti Grade 2 (330 MPa). Fatigue striation analysis showed that the fatigue crack propagation rate was not affected by manufacturing technology. In turn, the high-cycle fatigue life was drastically reduced as the size of manufacturing defects (such as pores or lack of fusion zones) increased.

Investigation of fatigue damage of new-old concrete interface based on piezomagnetic effect

Prefabricated concrete structures that employ wet connections create a new-old concrete interface between the pre-cast and cast-in-place layers. To enhance interfacial bonding performance in practical engineering, steel shear keys are frequently employed. The performance of the new-old concrete interface is critical in determining the fatigue performance of prefabricated concrete structures. Therefore, detecting and monitoring interface fatigue damage is essential for the life prediction and damage assessment of the entire structure. This study measured and analysed the piezomagnetic signal of the new-old concrete interface with shear keys under both static and cyclic loads. The piezomagnetic induction intensity was studied based on multiple damage indicators, such as steel strain and interface deformation. The relationship between the piezomagnetic signal and interface fatigue damage was analysed. The magneto-mechanical effect, dislocation effect, and magnetic leakage effect govern the piezomagnetic field change in different fatigue stages. It is found that the piezomagnetic signal exhibits similarities with conventional fatigue damage indicators, undergoing a three-stage variation pattern. Moreover, it demonstrates greater sensitivity to stress loading history and can better reflect the evolution of microstructural defects within the material. Finally, a simulated model of the magnetisation of the shear key at the new-old concrete interface was established and validated.

Correlation of Microstructure and Nanomechanical Properties of Additively Manufactured Inconel 718

Abstract Additive manufacturing (AM) has emerged as a crucial technology in recent decades, particularly within the aerospace industry. However, the thermally cyclic nature of these processes introduces significant variations and defects in microstructure, which can adversely affect final part performance and hinder the widespread adoption of the technology. Traditionally, characterization of AM parts has relied on conventional bulk testing methods, which involve analyzing many samples to gather sufficient data for statistical analysis. Unfortunately, these methods are unable to account for local nanoscale variations in material properties caused by the microstructure, as they measure a single averaged property for each tested sample. In this work, we use AM Inconel 718 as a model system in developing a novel approach to correlate nanomechanical properties obtained through nanoindentation with microstructure obtained through electron backscatter diffraction (EBSD). By associating mechanical properties obtained from each indent with the corresponding crystallographic direction, we calculate the weighted average hardness and modulus for each orientation. This enables us to generate inverse pole figure maps depicting the relationship between mechanical properties and crystallographic direction. Our method yields results in good agreement with literature when calculating the part modulus and hardness, while effectively capturing nanoscale variations in properties across the microstructure. The key advantage of this methodology is its capability to rapidly test a single AM part and generate a large dataset for statistical analysis. Complementing existing macroscale characterization techniques, this method can help improve AM part performance prediction and contribute to the wider adoption of AM technologies in the future.

The influence of microstructural orientation on fracture toughness in (V, Al)N and (V, Al)(O, N) coatings as measured by microcantilever bending

Since protective transition metal (oxy)nitride coatings are widely used, understanding of the mechanisms linking microstructure to their fracture behaviour is required to optimise wear resistance, while maintaining fracture toughness. To assess this interconnection, beam bending was performed using microcantilevers oriented parallel and at 90° to the growth direction. Furthermore, the tests were applied to favour normal bending and shear fracture. Coatings were synthesised by both direct current magnetron sputtering (DCMS) as well as high power pulsed magnetron sputtering (HPPMS). Here, we show that the fracture toughness depends on the alignment of the grains and loading directions. Furthermore, an improved fracture toughness was found in coatings produced by HPPMS, when microstructural defects, such as underdense regions in DCMS deposited coatings can be excluded. We propose indices based on fracture and mechanical properties to rank those coatings. Here, the HPPMS deposited oxynitride showed the best combination of mechanical properties and fracture toughness.Graphical abstractPrinciple of measuring the effects of microstructure and process route on the fracture toughness via microcantilever bending.

Rotating bending fatigue mechanisms of L-PBF manufactured Ti-6Al-4V alloys using in situ X-ray tomography

Lightweight titanium alloys are being increasingly used in high value structures, but in-depth knowledge of the rotating bending fatigue (RBF) mechanism remains insufficient, particularly for additively manufactured components. In response, an in situ RBF test rig was developed for the first time, using time-lapse synchrotron radiation X-ray microtomography (SR-μCT) to identify the failure behavior of laser powder bed fused Ti-6Al-4V alloys. The RBF damage evolution was characterized by combining the non-destructive SR-μCT with post-mortem scanning electron microscopy, and electron backscatter diffraction. Compared with RBF life data and fatigue long crack growth from standard specimens, in situ RBF tests proved to be reliable, in revealing the fatigue mechanism. However, fatigue short cracks in the representative mini RBF testing campaign were found to initiate from microstructural features of outer surfaces, instead of gas pores or lack of fusion defects. It is demonstrated that neither the standard nor the improved Kitagawa-Takahashi diagrams are unable to correlate the fatigue strength to manufacturing defects. The equivalent defect should include the effect of surface microstructural defects, in addition to internal defects, when studying additively manufactured alloys.

Influence of trace rare earth elements on very high cycle fatigue behavior of hot rolled bearing steel

In this study, the effect of trace rare earth (RE) elements on the fatigue property of bearing steel in very high cycle fatigue regime was investigated. For this purpose, ultrasonic tension–compression fatigue tests were conducted on specimens extracted from hot rolled bearing steels with and without RE addition. Crack propagation behavior within the characteristic “fish-eye” (FiE) area and the non-inclusion induced fatigue failure were analyzed after the fatigue test. Results showed that the addition of trace RE can modify inclusions to varying degrees. Further, it significantly reduces the volume fraction of inclusions as well as the number of large inclusions. Consequently, the fatigue life of bearing steel is more than doubled based on the 10% and 50% failure probabilities. During the propagation of cracks within the FiE area, the microstructure and intrinsic defects in bearing steel exhibit high sensitivity to the instantaneous driving force for crack propagation. The discontinuity in their size may result in abnormally slow crack propagation. For the non-inclusion induced fatigue failure of bearing steel, microcracks preferentially form at the junction of lath interfaces or at the enclosed area of martensite laths/plates which tend to grow along the interfaces perpendicular to the loading direction.

Defects in Metal Additive Manufacturing: Formation, Process Parameters, Postprocessing, Challenges, Economic Aspects, and Future Research Directions.

Metal additive manufacturing (AM) is a revolutionary technological advancement that has made significant inroads in a wide range of sectors, including aerospace, defense, automotive, health care, and engineering applications. It offers unprecedented design freedom, reduced material waste, and enhanced performance, in addition to significant enhancements to fabrication processes. Microstructural defects and internal stresses formed during fabrication directly affect the fabricated product's surface integrity, quality, and service life. Identification, characterization, and prediction of these defects help significant and direct production of defect-free structures with high density. This article provides detailed insights concerning the common defects, mitigation techniques, and challenges reported in both powder bed fusion-based and wire arc AM methods. Defects such as porosity may develop due to the powder sphericity, roughness of the powder, preheating, process parameters, build environment, postprocessing techniques, and environmental factors. Therefore, a critical study of the techniques, alloys, process parameter optimization, and different postprocessing techniques to tone down the defects is made from their formations.

Enhanced mechanical properties and biological responses of SLA 3D printed biphasic calcium phosphate bioceramics by doping bioactive metal elements

Favorable mechanical properties and outstanding bioactivity are necessary for bioceramics used for bone defect repair. The doping of Mg2+ and Fe3+ can improve the mechanical properties and bone regeneration capacity of calcium phosphate ceramics. In this study, magnesia oxide (MgO), ferric oxide (Fe2O3), and iron (Fe) powders are chosen as dopants to enhance biphasic calcium phosphate (BCP) bioceramics, and the MgO-BCP, Fe2O3-BCP, Fe-BCP bioceramics are prepared by stereolithography (SLA) for the first time. The effects of these dopants on the curing behavior of bioceramic slurries, mechanical properties, biodegradation, and cytocompatibility of BCP bioceramics are studied. The addition of 1 wt.% Fe well enhances the flexural strength of BCP from 91.61 MPa to 122.60 MPa sintered at 1250 oC. The addition of 1 wt.% MgO effectively promotes the biodegradation of BCP in simulated body solution (SBF), and enhances the proliferation of mouse pre-osteoblast (MC3T3-E1) cells in vitro. In addition, Fe powder is more suitable as a dopant for SLA 3D printed BCP than Fe2O3 powder, and all the performances of Fe-BCP are better than those of Fe2O3-BCP. The less microstructure defects and slower Fe3+ release rate make Fe-BCP have higher flexural strength and less cytotoxic compared with Fe2O3-BCP. This novel way exhibits beneficial effects of bioactive metal elements on mechanical properties and bioactivity, and indicates SLA 3D printed BCP bioceramic doped with MgO, Fe can be promising candidates for bone defect repair.

Additive Manufacturing of AISI 316L Stainless Steel: A Review

Additive manufacturing (AM) represents the present and the future of manufacturing production, thanks to a new design paradigm that allows the customization of components based on the needs of the final application, all framed in a perspective of sustainable and on-demand production. It has become an increasingly popular method for manufacturing complex and custom parts, especially those made from metallic materials, such as AISI 316L. AISI 316L is a type of austenitic steel widely used in industries such as aerospace, medical, automotive, and marine due to its excellent corrosion resistance and high strength. Thanks to its physico-chemical properties, AISI 316L stainless steel is one of the most used metals for AM. In this paper, a critical review of printing technologies, microstructural defects, mechanical properties, as well as industrial applications of AISI 316L are presented based on the state of the art. Furthermore, the main challenges with AM AISI 316L techniques are discussed, such as the influence of printing parameters, surface quality, and other common problems identified in the literature. Overall, this paper provides a comprehensive overview of AISI 316L AM techniques, challenges, and future research directions.

Insights into the atomic structure of oxygen vacancy on Bi2MoO6/MXene heterojunction and its role for boosting photocatalytic NO oxidation

Defect engineering is an effective approach to improve the gas conversion properties of photocatalysts. However, revealing the defect microstructures and performance enhancing mechanism remain challenges. In this work, the precise content and atomic-level structure of oxygen vacancy in Bi2MoO6/MXene heterojunction photocatalyst was studied by neutron scattering. Pair distribution function analysis shows that the vacancy percentage of oxygen connected with Mo in Bi2MoO6 is 16.6%, and the metal-O bond length decreases near the vacancy. The performance enhancement mechanism of oxygen vacancy in Bi2MoO6/MXene towards photocatalytic NO oxidation was investigated through experiments and density functional theory (DFT) calculations. The optical properties of the heterojunction photocatalyst can be significantly improved by the oxygen vacancies. The exposed Mo atoms at the vacancies greatly benefit the adsorption and activation of reactants, and also accelerate the generation of reactive oxygen species. The NO removal efficiency of the oxygen vacancy-containing Bi2MoO6/MXene heterojunction can reach up to 94.3% under visible light. This work provides a new approach for studying the microstructure and activity enhancement mechanism of oxygen vacancy in photocatalysts.

Inclusions and Segregations in the Selective Laser-Melted Alloys: A Review

This paper aims to review some important microstructural defects arising in the alloys manufactured by selective laser melting (SLM) or laser powder bed fusion (LPBF). During the manufacturing process, various defects can occur in metals, which can negatively impact their mechanical properties and structural integrities. These defects include gas pores, lack of fusions, keyholes, melt pools, cracks, inclusions, and segregations. In this review, heterogeneities such as inclusion and segregation defects are discussed. Other types of defects have been comprehensively discussed in other reviews. Inclusions refer to foreign ceramic particles that are present within the metal, whereas segregations refer to the uneven distribution of alloying elements within the microstructure of the metal. The cause of appearance, effect of different parameters, and methods to reduce them in the final part are also reviewed. The effects of these defects on the integrity of the produced parts are discussed. Solutions for the elimination or minimization of these defects are also suggested. Post treatments and modifications of an alloy’s composition can also help to improve its material properties and reduce its defect concentration.

Tailoring microstructural features of Cr3C2-25NiCr coatings through diverse spray variants and understanding the high-temperature erosion behavior

Thermal sprayed Cr3C2-NiCr coatings are widely used to protect industrial components from ambient or elevated erosive degradation. Various thermal spraying techniques such as plasma spray, detonation spray (DS), high velocity oxy-fuel (HVOF) and high velocity air-fuel spray (HVAF) are widely used to deposit Cr3C2-NiCr coatings. The choice of thermal spraying technique governs the inflight particle velocity and temperature, resulting in unique coating microstructural features, characteristics and erosion performance. In this study, Cr3C2-NiCr coatings are deposited through HVAF, DS and axial plasma spray. A comprehensive comparative analysis was performed to understand the process-structure-property relationship of Cr3C2-NiCr coatings, which correlated with the room and high temperature erosion performance. HVAF spray deposited Cr3C2-NiCr coatings with preferred microstructural features and properties, ensuring superior (high/room temperature) erosive resistance. Cr3C2-NiCr coatings deposited via DS spray performed second best, while plasma sprayed exhibited defective microstructure with inferior mechanical properties, resulting in substandard erosion performance.

Effect of Sintering Temperature on the Thermoelectric Properties of Ag2Se Fabricated by Spark Plasma Sintering with High Compression

Silver selenide (Ag2Se) is a high‐performance thermoelectric (TE) material near room temperature. This research improves its TE figure‐of‐merit (ZT) by varying the sintering temperatures (423–723 K) in the spark plasma sintering (SPS) process with high compression pressure (300 MPa). The SPS compaction of Ag2Se powders synthesized by wet chemical reaction leads to the fast fusion of particles so that the grain boundaries are hardly visible. Furthermore, the fast fusion causes nanopores at the grain surface and some cracks, particularly at higher sintering temperatures. These featured microstructures decrease carrier concentrations and affect the TE properties significantly. The TE measurements show that increasing sintering temperatures results in decreased electrical conductivity and increased magnitude of the Seebeck coefficient due to microstructural defects. Increasing SPS temperatures also suppresses the thermal conductivity from enhancing phonon scattering by defects. The bulk Ag2Se sample sintered at 723 K shows the best TE performance with the maximum ZT of 0.90 with a slight variation from 300 to 400 K. Thus, the high‐temperature SPS with high‐compression pressure is likely to be the key for fabricating bulk Ag2Se with high TE performance.

Numerical Modeling of the Micromechanics Damage of an Offshore Electrical High-Voltage Phase

Due to the strong growth of offshore renewable energies, research and engineering in this field is constantly expanding. One of the centerpieces of these technologies is the high-voltage electrical cable, generally made of copper, to transport the energy produced from the offshore farm to the onshore station. The critical nature of these cables lies in the proven resistance that they must demonstrate during stays underwater for several years, even decades, in difficult environmental conditions, which begin at the handling, shipping and underground burial stage. The marine environment can lead to deformation of the copper wires well beyond the limit of proportionality and, consequently, to breakage. Copper, although being an exceptional electrical conductor, has very poor mechanical properties. The plasticity generated by the excessive deformation of copper wires affects all of the physical properties of copper. When plasticity develops, electrical transport is affected and the heat within copper increases, but care should be given to not exceed 90 °C, as this would result in the shutdown of the cable with dramatic economic consequences. The work carried out in this article, which is part of the National Project EMODI as well as the European Project FLOW-CAM, aims at studying the mechanical behavior of the phase in order to correlate the deformation levels reached to the phase geometry as well as operating mechanisms of damage which reflect the proliferation of microstructural defects within the conductor. To do this, we propose a numerical model using Abaqus. Correct description of the effects of several parameters (geometry of the phase) and plasticity development on the performance of the phase were simulated and discussed.