Rapid Solidification Conditions Research Articles

GrainGNN: A dynamic graph neural network for predicting 3D grain microstructure

We propose GrainGNN, a surrogate model for the evolution of polycrystalline grain structure under rapid solidification conditions in metal additive manufacturing. High fidelity simulations of solidification microstructures are typically performed using multicomponent partial differential equations (PDEs) with moving interfaces. The inherent randomness of the PDE initial conditions (grain seeds) necessitates ensemble simulations to predict microstructure statistics, e.g., grain size, aspect ratio, and crystallographic orientation. Currently such ensemble simulations are prohibitively expensive and surrogates are necessary.In GrainGNN, we use a dynamic graph to represent interface motion and topological changes due to grain coarsening. We use a reduced representation of the microstructure using hand-crafted features; we combine pattern finding and altering graph algorithms with two neural networks, a classifier (for topological changes) and a regressor (for interface motion). Both networks have an encoder-decoder architecture; the encoder has a multi-layer transformer long-short-term-memory architecture; the decoder is a single layer perceptron.We evaluate GrainGNN by comparing it to high-fidelity phase field simulations for in-distribution and out-of-distribution grain configurations for solidification under laser power bed fusion conditions. GrainGNN results in 80%–90% pointwise accuracy; and nearly identical distributions of scalar quantities of interest (QoI) between phase field and GrainGNN simulations compared using Kolmogorov-Smirnov test. GrainGNN's inference speedup (PyTorch on single x86 CPU) over a high-fidelity phase field simulation (CUDA on a single NVIDIA A100 GPU) is 150×–2000× for 100-initial grain problem. Further, using GrainGNN, we model the formation of 11,600 grains in 220 seconds on a single CPU core.

Rapidly solidified Al-Cu-Co quasicrystalline alloy: microstructure and catalytic properties

This study presents the characterisation and evaluation of the catalytic potential of an alloy with a composition referring to the quasicrystal from the Al-Cu-Co system. The material was synthesised through a melt-spinning process, providing rapid solidification conditions and a favourable material form of thin ribbons. Microstructural and chemical analyses were performed using scanning electron microscopy, X-ray diffraction and transmission electron microscopy methods. The obtained results confirmed the presence of a major phase which was a decagonal quasicrystal in the form of globular grains and additional crystalline phases occurring along the grain boundaries. The catalytic potential of the materials was explored using phenylacetylene hydrogenation. The catalyst, obtained by pulverising the ribbons, demonstrated catalytic activity with over 40% phenylacetylene conversion and selectivity exceeding 60% for styrene production under mild reaction conditions. The recovered catalyst displayed a stable phase composition, as confirmed by X-ray diffraction, and unchanged morphology, indicating the possibility of catalyst reuse for subsequent reaction cycles. The presented results provide insight into the experimental verification of the catalytic properties of the developed environmentally friendly catalysts.

Modeling of rapid solidification in Laser Powder Bed Fusion processes

This paper addresses a numerical framework for modeling site-specific microstructure evolution in Laser Powder Bed Fusion (LPBF), where rapid solidification significantly influences the microstructure and properties of manufactured components. The fine microstructure and rapid solidification can enhance mechanical properties in final parts, yet pose challenges in controlling microstructure and addressing potential defects. In this study, an in-house developed free surface thermo-fluidic Computational Fluid Dynamics (CFD) model is coupled with a binary alloy phase-field model characterized by rapid solidification kinetics. The CFD model considers complex fluid flows related to Marangoni and recoil pressure, laser-material interactions, and rapid melting and solidification of the melt pool. A convergence study for the phase-field model is conducted, comparing simulated partition coefficients with the Continuous Growth Model (CGM) theory. The study investigates the individual effects of temperature gradients and solidification rates on simulated microstructure. Results indicate that, for the same order of magnitude change, the solidification rate has a more pronounced effect on microstructure than temperature gradients. The paper concludes with the simulation of site-specific microstructure evolution within the melt pool, comparing the results with experiments conducted at varied scanning speeds. The predicted microstructure aligns well with experimental measurements, suggesting the potential utility of the developed phase-field model in quantitative microstructural modeling. Overall, this work contributes to understanding microstructure evolution under rapid solidification conditions, providing a fundamental basis for optimizing the LPBF process.

Enhancing Surface Properties of Cu-Fe-Cr Alloys through Laser Cladding: The Role of Mo and B4C Additives

Laser cladding is a powerful surface treatment technique that can significantly enhance the properties of metal alloys. This study delves into the liquid phase separation behavior of Cu-Fe-Cr alloys under the rapid solidification conditions inherent in laser cladding and evaluates the influence of 4% Mo and 2% B4C additions on the resulting alloy characteristics. The intensive undercooling characteristic of the laser cladding process facilitates the alloy’s entry into the liquid-phase immiscibility gap, prompting pronounced phase separation. Our investigation reveals the emergence of Fe-rich regions, exhibiting a variety of shapes, set against a continuous Cu-rich matrix. The incorporation of Mo and B4C was found to modulate the mixing enthalpy and entropy, thereby refining the phase distribution: Mo was observed to prevent the agglomeration of Fe cores, resulting in a dispersion of isolated Fe cores throughout the Cu-rich matrix, while B4C promoted a more uniform compositional distribution. This study further enumerates the enhancements in microhardness, wear resistance, and magnetic properties of the alloys. Notably, the Cu-Fe-Cr-Mo-B4C alloy demonstrated a microhardness exceeding 600 HV, a low coefficient of friction around 0.15, high saturation magnetization, and reduced coercivity. These results underscore the efficacy of laser cladding in tailoring the microstructure and properties of Cu-Fe alloys, providing insights for the controlled manipulation of phase separation to optimize surface characteristics for engineering applications.

A Comparison of Solidification Structures and Submicroscale Cellular Segregation in Rapidly Solidified Stainless Steels Produced via Two-Piston Splat Quenching and Laser Powder Bed Fusion.

Fusion-based additive manufacturing techniques leverage rapid solidification (RS) conditions to create parts with complex geometries, unique microscale/nanoscale morphological features, and elemental segregation. Three custom composition stainless steel alloys with varying chromium equivalence to nickel equivalence ratio (Creq/Nieq) between 1.53 and 1.95 were processed using laser powder bed fusion (LPBF) and/or two-piston splat quenching (SQ) to produce solidification rates estimated between 0.4 and 0.8 m/s. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to collect high-resolution images, electron backscatter diffraction (EBSD) phase identification, and measure cellular segregation. Similar features were observed in both LPBF and SQ samples including phase and microstructure, nanoscale oxide particles, cell size, and segregation behavior. However, dislocation pileup was observed along the cell boundaries only in the LPBF austenite solidified microstructure. Targeted adjustment of the SQ feedstock Cr and Ni concentrations, within the ASTM A240 specification for 316L resulted in no observable impact on the cell size, oxide particle size, or magnitude of segregation. Also, the amount of Ni segregation in the ferrite solidified microstructures did not significantly differ, regardless of Cr/Nieq or processing technique. SQ is demonstrated as capable of simulating RS rates and microstructures similar to LPBF for use as an alternative screening tool for new RS alloy compositions.

Microstructural Evaluation and Tensile Properties of Al-Mg-Sc-Zr Alloys Prepared by LPBF

Laser powder bed fusion (LPBF) is a typical additive manufacturing technology that offers significant advantages in the production of complex components. With the rapid heating and cooling characteristics of LPBF, a large amount of solid solution of alloying elements in the matrix can be achieved to form supersaturated solid solutions, thus enhancing the properties of LPBF alloys. For the unique microstructure, the heat treatment process needs to be adjusted accordingly. In this work, a Zr/Sc-modified Al-Mg alloy processed by laser powder bed fusion (LPBF) with relatively low cost and good mechanical properties was investigated. The fine microstructure was obtained under rapid solidification conditions. The nanoscale Al3(Sc,Zr) particles precipitated at the molten pool boundary during solidification. These particles, as effective heterogeneous nucleators, further refined the α-Al grains and improved the mechanical properties of the alloy. As a result, the alloy exhibited a heterogeneous microstructure consisting of columnar grains in the center of the molten pool and equiaxed grains at the boundaries. The rapid solidification resulted in the supersaturation of solute atoms in the α-Al matrix, which significantly enhanced the solid solution strengthening effect. With the LPBF processing parameters of a combination of a laser power of 250 W, a laser scanning speed of 833 mm/s, and stripe scanning mode, the tensile strength of the alloy reached 401.4 ± 5.7 MPa, which was significantly higher than that of the cast alloys with aging treatment (281.1 ± 1.3 MPa). The heat treatment promoted the formation of secondary Al3(Sc,Zr), Mn/Mg-rich phases. The ultimate tensile strength and elongation at fracture after aging at 325 °C for 2 h were 536.0 ± 1.7 MPa and 14.8 ± 0.8%, respectively. The results provide insight into the preparation of aluminum alloys with relatively low cost and excellent mechanical properties.

Molecular dynamics simulation of Fe-Si alloys using a neural network machine learning potential

Interatomic potential development using machine learning (ML) approaches has attracted a lot of attention in recent years because these potentials can effectively describe the structural and dynamical properties of complex materials at the atomistic level. In this work, we present the development of a neural network (NN) deep ML interatomic potential for Fe-Si alloys, and we demonstrate the effectiveness of the NN-ML potential in predicting the structures and energies of liquid and crystalline phases of Fe-Si alloys in comparison with the results from ab initio molecular dynamics simulations or experimental data. The developed NN-ML potential is also used to perform molecular dynamics simulations to study the structures of Fe-Si alloys with various compositions under rapid solidification conditions. The short-ranged orders in the rapidly solidified Fe-Si alloys are also analyzed by a cluster alignment method.

High strength Hadfield steel produced using laser powder bed fusion of mixed powders

Hadfield steel (HS) containing ∼0.83 wt% Carbon has been manufactured using the laser powder bed fusion (LPBF) of mixed Fe-Mn, pure-Fe and Fe-C powders. Results show that the as-fabricated alloy is fully austenitic with the absence of carbides—a typical feature in the cast alloy that necessitates its solutionizing and quenching. The strength (σy = 595.5 ± 18.1 MPa, σu = 950.2 ± 28.6 MPa) and hardness (318.6 ± 7.1 HV) of the LPBF HS are superior to those of the conventionally fabricated HS, while the impact toughness is similar, and ductility is inferior. The yield strength enhancement is mainly due to the refinement in the grain size and increase in the dislocation density, which occurs due to the rapid solidification conditions that prevail during LPBF. This rapid solidification also prevents carbide formation and retain the main alloying elements (C and Mn) in solution. Thus conventional water quenching process can be completely eliminated.

A 3D Multiscale Model for Prediction of the Microstructure Evolution in Ti6Al4V Components Produced by Laser Powder Bed Fusion

A transient 3D multiscale model has been created to simulate the evolution of solidification microstructures rapidly and effectively in Ti6Al4V parts produced through Laser Powder Bed Fusion (LPBF). The microstructure simulation tool has been enhanced to account for rapid solidification conditions in Ti6Al4V alloys during processing of multi-layer multi-track LPBF parts. The simulation tool can evaluate the impact of part geometry, lase power input, laser speed, and laser beam shape on the formation of the microstructure in LPBF-processed Ti6Al4V alloy. The multiscale model considers several factors, including preferential crystallographic growth direction, isomorphism, epitaxy, melt pool motion, and temperature gradients to generate the observed texture and morphology of the microstructure in Ti6Al4V components. The model can evaluate various microstructure characteristics, such as grain size and texture. Consequently, it could aid in controlling the formation of solidification microstructures in Additive Manufacturing (AM) processed parts. The simulation tool has been previously validated by using IN625 laser remelting experiments made by National Institute of Standards and Technology. The 3D simulation tool can also be utilized to predict the microstructure formation in Ti6Al4V components produced by the Electron Beam AM processes.

A 3D simulation of grain structure evolution during laser rescanning process of powder bed fusion additive manufacturing

Laser powder bed fusion (LPBF) is an extensively used additive manufacturing process that can build metal parts with complicated geometric designs. However, because of the rapid solidification conditions and the layer-by-layer building, its application is challenged by products having poor surface quality and reduced mechanical properties. The laser rescanning process is often used as a refinement method during LPBF to improve the quality of products. In this study, grain structure formation during the LPBF laser rescanning process is modelled by a 3D cellular automaton based microstructure model coupled with finite element analysis. The coupled model considers different nucleation mechanisms, including epitaxial growth, which are applicable to rapid solidification in melt pool. The model is adapted to reproduce the grain structure and evolution of an Al-Si alloy manufactured by LPBF utilizing a laser rescanning strategy. The effects of laser remelting on the characteristics of the grain structure (i.e., the grain size, aspect ratio and orientation) are evaluated. The mechanisms that enable unique grain structure (i.e., grain refinement) are discussed.

Morphological stability of solid-liquid interfaces under additive manufacturing conditions

Understanding rapid solidification behavior at velocities relevant to additive manufacturing (AM) is critical to controlling microstructure selection. Although in-situ visualization of solidification dynamics is now possible, systematic studies under AM conditions with microstructural outcomes compared to solidification theory remain lacking. Here we measure solid-liquid interface velocities of Ni-Mo-Al alloy single crystals under AM conditions with synchrotron X-ray imaging, characterize the microstructures, and show discrepancies with classical theories regarding the onset velocity for absolute stability of a planar solid-liquid interface. Experimental observations reveal cellular/dendritic microstructures can persist at velocities larger than the expected absolute stability limit, where banded structure formation should theoretically appear. We show that theory and experimental observations can be reconciled by properly accounting for the effect of solute trapping and kinetic undercooling on the velocity-dependent solidus and liquidus temperatures of the alloy. Further theoretical developments and accurate assessments of key thermophysical parameters – like liquid diffusivities, solid-liquid interface excess free energies, and kinetic coefficients – remain needed to quantitatively investigate such discrepancies and pave the way for the prediction and control of microstructure selection under rapid solidification conditions.

Heredity of clusters in liquid Ta rapid solidification process and its correlation with local symmetry

Metallic glass (MG) has received intensive attention in the fields of amorphous physics and materials science, owing to its excellent mechanical properties, good corrosion resistance, and large elastic deformation limit. Comparing with traditional oxide glass, the limited glass-forming ability (GFA) seriously restricts the application of MG in engineering. Therefore, the GFA has been a hot scientific issue in the field of amorphous material research. Recently, scientists have fully realized that GFA is closely related to the local atomic structure in liquid as well as its evolution features. Since the MG is called the “freezing” liquid, exploring the correlation of local atomic structures between liquid phase and solid phase under rapid solidification conditions is helpful in understanding the microstructural mechanism of GFA. Therefore, the rapid solidification process of liquid Ta is investigated via molecular dynamics simulation. The pair correlation function (PDF), the largest standard cluster (LSC), and the reverse atomic trajectory tracking methods are used to characterize and analyze the microstructure and its evolution during the rapid solicitation of liquid Ta. The results show that the local atomic configurations of the rapidly solidified Ta are various Kasper clusters as well as their distorted configurations, among of which [1/444, 10/555, 2/666] deformed icosahedron (or Z13 cluster) accounts for the highest proportion. The trend of hereditary ability of clusters revealed by the onset temperature of continuous heredity is consistent well with that by the fraction of staged heredity. The geometric symmetry of clusters can be quantitatively characterized by using the local symmetry parameter (LSP). The hereditary ability of clusters is closely related to their LSP. The local five-fold symmetry is beneficial to enhancing hereditary ability, while local four- and six-fold symmetry are disadvantageous for that. The probability of clusters with the same LSC index emerging in the energy range follows the Gaussian distribution, and the expected average atomic potential energy <inline-formula><tex-math id="M3">\begin{document}$ {E}_{\rm exp}^{j} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20231153_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20231153_M3.png"/></alternatives></inline-formula> is almost linearly related to the LSP, and <inline-formula><tex-math id="M4">\begin{document}$ {E}_{\rm exp}^{j} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20231153_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20231153_M4.png"/></alternatives></inline-formula> decreases with the increase of LSP<sub>5</sub>. The high local five-fold symmetry reduces the average atomic potential energy of LSC, thereby enhancing its configurational heredity. These findings have guiding significance in improving GFA through regulating the local symmetry of liquid monatomic metals or alloys.

3D Modeling of the Solidification Structure Evolution and of the Inter Layer/Track Voids Formation in Metallic Alloys Processed by Powder Bed Fusion Additive Manufacturing.

A fully transient discrete-source 3D Additive Manufacturing (AM) process model was coupled with a 3D stochastic solidification structure model to simulate the grain structure evolution quickly and efficiently in metallic alloys processed through Electron Beam Powder Bed Fusion (EBPBF) and Laser Powder Bed Fusion (LPBF) processes. The stochastic model was adapted to rapid solidification conditions of multicomponent alloys processed via multi-layer multi-track AM processes. The capabilities of the coupled model include studying the effects of process parameters (power input, speed, beam shape) and part geometry on solidification conditions and their impact on the resulting solidification structure and on the formation of inter layer/track voids. The multi-scale model assumes that the complex combination of the crystallographic requirements, isomorphism, epitaxy, changing direction of the melt pool motion and thermal gradient direction will produce the observed texture and grain morphology. Thus, grain size, morphology, and crystallographic orientation can be assessed, and the model can assist in achieving better control of the solidification microstructures and to establish trends in the solidification behavior in AM components. The coupled model was previously validated against single-layer laser remelting IN625 experiments performed and analyzed at National Institute of Standards and Technology (NIST) using LPBF systems. In this study, the model was applied to predict the solidification structure and inter layer/track voids formation in IN718 alloys processed by LPBF processes. This 3D modeling approach can also be used to predict the solidification structure of Ti-based alloys processes by EBPBF.

Effect of microsegregation behaviors on solidification microstructure of IC10 superalloy fabricated by directed energy deposition

Due to the solidification process and thermal history, the microstructure and properties along the deposition direction are generally inhomogeneous in components fabricated by the directed energy deposition technique. By developing a microsegregation model, this study gives an innovative understanding of the elemental segregation behavior of an as-deposited IC10 superalloy along the different heights and its influence on the microstructure. Results indicate that the γ-γ ´ eutectic-free microstructure is only obtained at the initial deposition layer, and as the deposition height increases, eutectic phases gradually appear in interdendritic regions. By taking account of the nonequilibrium solidification and dendritic tip undercooling, the new microsegregation model can well explain the segregation behavior of the alloy at different deposition heights. Compared to the back diffusion coefficient, the partition coefficient plays a major role in microsegregation behavior under rapid solidification conditions, especially for the elements with a high diffusion coefficient in solid, such as Ti and Al. Moreover, microstructure transformation is dependent on varying solidification processes due to the change in microsegregation. Limited by the heat transfer efficiency as the increased deposition heights, the temperature gradient and solidification rate decrease, which exacerbates the enrichment of Al and Ti at interdendritic regions and promotes the eutectic phase nucleation. Restricted by the diffusion rate of alloying elements, the eutectic reaction rate slows down, γ and γ ´ lamellae thickness increase, and finally the petal-like eutectic phases form.

Hierarchical architecture and mechanical behavior of K418 Ni-based superalloys manufactured by laser powder bed fusion

Laser powder bed fusion (LPBF) has great potential in the manufacturing of difficult-to-cut Ni-based superalloys with complex geometries. The approach endows the alloys with multi-scale microstructure hierarchy, while its formation mechanism and contribution to mechanical properties are poorly understood. In this work, the hierarchical architecture in LPBF-fabricated K418 Ni-based superalloys, in terms of 3D interlocked grains, low-angle grain boundaries (LAGBs), cellular structure, inter-cellular segregation, and nano-sized γ′ precipitates and carbides, is comprehensively investigated. The formation of cellular structure is governed by the rapid solidification condition, and the 3D interlocked grain structure is associated with the cell growth behavior regulated by locally varied temperature gradient in the melt pool. The LPBF K418 alloys show a higher tensile strength but a slightly lower ductility at both room temperature and 600 °C than their conventional cast counterparts. The superior strength of LPBF alloys is dominantly attributed to the strengthening effect of interlocked grain boundaries and cellular microstructure. This work demonstrates the capability of LPBF to manufacture Ni-based superalloys with hierarchical microstructures and high performance for the application of hot-section gas turbine components.

Ambient pressure fabrication of Ni-free high nitrogen austenitic stainless steel using laser powder bed fusion method

A novel one-step method for fabricating Ni-free high N austenitic stainless steel components at ambient pressure using metal nitride powders as the nitrogen source by the additive manufacturing technology of laser powder bed fusion (LPBF) is demonstrated. It exploits the rapid solidification conditions inherent to the LPBF process for the retention of N in solid solution instead of evaporation. A fully austenitic steel with a high N content of 0.87 wt% has been obtained. The solute strengthening induces more than 70% improvement in hardness and ~ 59% increase in yield strength compared to the LPBF fabricated SS316L and shows promising corrosion resistance. X-ray diffraction, X-ray photoelectron spectroscopy, electron backscattered diffraction were utilized to study the microstructures and relate them to the properties at multi-scales.

Effects of shear flows on columnar dendritic microstructure during rapid solidification of IN718 alloy: A cellular automaton-lattice Boltzmann modeling study

The growth of columnar dendrites during rapid directional solidification of IN718 alloy in the presence of shear flows is simulated by using a coupled cellular automaton-lattice Boltzmann (CA-LB) model. The developed CA-LB model is benchmarked by the mesh independency of the steady-state dendrite growth velocity and the primary dendrite arm spacing (PDAS) under different cooling rates. The CA-LB model is then applied to simulate the columnar dendrite growth under different shear flows and cooling rates in the conditions of rapid solidification. The values of PDAS under different conditions are determined from the simulation results, and are correlated with the shear flow rate (Ush) and cooling rate (CR). A unified fitting formula is developed to represent the effects of Ush and CR on the evolution of PDAS. The PDAS is found to decrease with CR increasing, but increase with Ush increasing. Moreover, it is revealed that the influence of Ush on PDAS becomes stronger as CR increases.

A Co-free Cr-Fe-Ni-Al-Si high entropy alloy with outstanding corrosion resistance and high hardness fabricated by laser surface melting

In this paper, a CrFeNiAl0.2Si0.2 high entropy alloy (HEA) was fabricated via laser-surface melting (LSM). The result shows that, this HEA could form fully BCC structure under such rapid-solidification condition. Moreover, it exhibits excellent corrosion resistance in 3.5 wt% NaCl solution with two-stage passivation, and could maintain good protectiveness until 1.06 V vs SCE during electrochemical polarization, which is much higher than stainless steel. In addition, this rapid-solidified HEA shows high hardness of ∼667 Hv. Such excellent corrosion resistance and unique passivation process are possibly caused by the diversity in compositional constitution of the passive films under different electrochemical corrosion conditions. This work provides a novel route for designing low-cost corrosion-resistant HEAs with high hardness for coating applications.

EBSD and EDX analysis at the cladding–substrate interface of a laser clad railway wheel

Abstract Electron backscatter diffraction and energy-dispersive X-ray spectrometry were used to investigate the intermixed interface produced during laser cladding of a Co – Cr –Mo alloy on a steel substrate. A multi-component system and rapid solidification conditions together lead to a complex microstructure at the interface. The solidification of the cladding starts with the formation of an interface layer, which is about 75 μm in thickness and consists of randomly oriented equiaxed grains of Co–Cr –Fe solid solution and martensite. Orientation analysis of the grains in the interface layer revealed that some grains have a special orientation relationship with the former austenite grains in the heat affected zone but the cladding is not formed by epitaxial growth on the substrate. Intermixing of the materials at the interface is providing a strong bond between the substrate and the cladding. For a grain from the interface layer to emerge as columnar grain in the cladding, it was determined that its <001> crystallographic direction is not supposed to deviate more than 25° from the sample normal direction.

Effect of Rapid Solidification Processing on the Microstructure and Corrosion of 316L Austenitic Stainless Steel

Austenitic stainless steels processed by rolling are widespread in technological applications, since they have excellent mechanical and corrosion properties. This study investigated the effect of the cooling rate, microstructure and properties of 316L austenitic stainless steel under cold rolled conditions and by rapid solidification. The microstructure of the cold rolling processing steel was composed of austenite and a low percentage of delta ferrite. For the rapid solidification condition, the microstructure evolved from columnar and acicular dendrites to equiaxed dendrites with decreasing cooling rates, without the presence of delta ferrite due to the high cooling rate. Furthermore, thermal analyses in both routes revealed that oxidation kinetics was slower after rapid solidification in synthetic air. The microhardness in the cold rolling condition was lower than in the rapid solidification condition since the microstructure under the solidification condition is more refined. The sample in the rapid solidification condition region RS1 presented the highest corrosion resistance considering the pit potential. The passivation current density in the cold rolled condition was 5.72x10-5A/cm2, while under the rapid solidification condition, regions RS1 and RS2 were 2.24x10-5 A/cm2 and 3.72x10-6 A/cm2, respectively, and region RS3, did not present a passivation region in a broad range of potentials.