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Laser Powder-bed Fusion (L-PBF) is a promising additive manufacturing (AM) process that is capable of speedily fabricating functional components typically used for aerospace, automotive, microelectronics, and biomedical applications. In this study, a 3-D computational fluid dynamics model with Ti-6Al-4V powder-bed is developed incorporating a moving conical volumetric heat source and thermophysical properties of Ti-6Al-4V alloy to conduct the simulations of the L-PBF process. The melt-pool dynamics and its thermal behavior are investigated numerically and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and enthalpy are obtained for different laser irradiation conditions. Simulation results show that the maximum temperature, dimensions, and liquid lifetime of the melt pool increase with the increase of the laser power and decrease of the scanning speed. A custom ytterbium fiber laser system is applied to perform laser melting experiments with a solid Ti-6Al-4V specimen. The microstructures of the cross-sectional areas are examined by a scanning electron microscope to observe the melt-pool dimensions and the heat-affected zones. Finally, the simulation results for melt-pool geometry are compared with the experimental results to validate the numerical model for the L-PBF process.

Powder-bed fusion (PBF) process is a subdivision of additive manufacturing (AM) technology where a heat source at a controlled speed selectively fuses regions of a powder-bed material to form three-dimensional (3D) parts in a layer-by-layer fashion. Two of the most commercialized and powerful PBF methods for fabricating full-density metallic parts are the laser PBF (L-PBF) and electron beam PBF (E-PBF) processes. In this study, a multiphysics-based 3D numerical model is developed to compare the thermo-fluid properties of Ti-6Al-4V melt pools formed by the L-PBF and E-PBF processes. The temperature-dependent properties of Ti-6Al-4V alloy and the parameters for the laser and electron beams are incorporated in the model as the user-defined functions (UDFs). The melt-pool geometry and its thermo-fluid behavior are investigated using the finite volume (FV) method, and results for the variations of temperature, thermo-physical properties, velocity, geometry of the melt pool, and cooling rate in the two processes are compared under similar irradiation conditions. For an irradiance level of 26 J/mm3 and a beam interaction time of 1.212 ms, simulation results show that the L-PBF process gives a faster cooling rate (1. 5 K/μs) than that in the E-PBF process (0.74 K/μs). The magnitude of liquid velocity in the melt pool is also higher in L-PBF than that in E-PBF. The numerical model is validated by comparing the simulation results for the melt-pool geometry with the PBF experimental results and comparing the numerical melt-front position with the analytical solution for the classical Stephan problem of melting of a phase-change material (PCM).

Forming processes are a convenient means for bulk production of parts. These parts are used in a wide range of applications from automotive industries to micro-devices in bioengineering. Manufactured parts are required to be precise in their final dimension, and since the billet material undergoes significant plastic deformation during forming, billet material characterization and prediction of final form is essential. In this study, miniaturized bowl-shaped samples of 3003-H14 aluminum alloy were formed using a die and punch manufactured using the stereolithography (SLA) additive manufacturing method. Tensile testing was performed in order to characterize the material properties of the SLA resin. Using the SLA-created die and punch, hemispherical bowl-shaped forms were generated. In order to investigate possible small size effects, experimental load versus displacement results were obtained for billet plate thicknesses of 0.4–0.8 mm. A numerical finite element model was developed to predict the required punch load to manufacture various thickness bowl-shaped forms. A comparison was made between the load verses displacement curves for the different thicknesses, and the numerical model was validated by the experimental results. The validated computational model can then be used to predict the process parameters prior to starting bulk production. Finally, a model with grains was developed and simulated to show the virtual microstructural morphology of the circular plates before and after the forming operation.

Selective laser melting (SLM) is a growing additive manufacturing (AM) technology which is capable of rapidly fabricating functional components in the medical and aviation industries. The thermophysical properties and melt-pool dynamics involved in the powder-bed SLM process play a crucial role to determine the part quality and process optimization. In this study, a 3-D computational fluid dynamics (CFD) model with Cu-Cr-Zr (C-18150) powder-bed is developed incorporating a moving conical volumetric heat source and temperature-dependent thermal properties to conduct the Multiphysics simulations of the SLM process. The melt-pool dynamics and its thermal behavior are investigated numerically and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and velocity in the melt pool are obtained for different laser beam specifications. The validation of the CFD model is conducted by comparing the simulation results for temperature and the melt-front motion with the analytical results found from the classical Stefan problem of the phase-change material. Studying the process parameters, melt-pool geometry, and thermal behavior of Cu-Cr-Zr alloy can generate valuable information to establish Cu-Cr-Zr as a low-cost engineering material in the AM industry.

This study describes a method for investigating the modal characteristics and the structural aerodynamic response of the crane fly (family Tipulidae) forewing under different airflow conditions. A micro-computed tomography scan is conducted to characterize the internal and external morphologies of the insect wing. A finite element model of the crane fly forewing is developed to determine its natural frequencies and mode shapes. The FE model is validated by comparing the natural frequencies of a beam with similar mechanical properties and geometric characteristics of those from the veins of the crane fly forewing to its analytical solution from the Euler–Bernoulli beam theory. A numerical simulation of the fluid–structure interaction is conducted by coupling the finite element model of the crane fly forewing with a computational fluid dynamics model of the surrounding airflow. From this simulation, the deformation response and the coefficients of drag and lift of the insect wing are predicted for different Reynolds numbers and angles of attack. The mode shapes show regions of low stiffness at the trailing and leading edges of the wing. The deformation increases nonlinearly from the root to the tip of the wing, and the aerodynamic efficiency of the insect wing increases with angle of attack and freestream velocity, especially for high Reynolds numbers.

Electron beam additive manufacturing (EBAM) is a powder-bed fusion additive manufacturing (AM) technology that can make full density metallic components using a layer-by-layer fabrication method. To build each layer, the EBAM process includes powder spreading, preheating, melting, and solidification. The quality of the build part, process reliability, and energy efficiency depends typically on the thermal behavior, material properties, and heat source parameters involved in the EBAM process. Therefore, characterizing those properties and understanding the correlations among the process parameters are essential to evaluate the performance of the EBAM process. In this study, a three-dimensional computational fluid dynamics (CFD) model with Ti-6Al-4V powder was developed incorporating the temperature-dependent thermal properties and a moving conical volumetric heat source with Gaussian distribution to conduct the simulations of the EBAM process. The melt pool dynamics and its thermal behavior were investigated numerically, and results for temperature profile, melt pool geometry, cooling rate and variation in density, thermal conductivity, specific heat capacity, and enthalpy were obtained for several sets of electron beam specifications. Validation of the model was performed by comparing the simulation results with the experimental results for the size of the melt pool.

Selective Laser Melting (SLM) and Electron Beam Additive Manufacturing (EBAM) are two of the most promising additive manufacturing technologies that can make full density metallic components using layer-by-layer fabrication methods. In this study, three-dimensional computational fluid dynamics models with Ti-6Al-4V powder were developed to conduct numerical simulations of both the SLM and EBAM processes. A moving conical volumetric heat source with Gaussian distribution and temperature-dependent thermal properties were incorporated in the thermal modeling of both processes. The melt-pool geometry and its thermal behavior were investigated numerically and results for temperature profile, cooling rate, variation in specific heat, density, thermal conductivity, and enthalpy were obtained with similar heat source specifications. Results obtained from the two models at the same maximum temperature of the melt pool were then compared to describe their deterministic features to be considered for industrial applications. Validation of the modeling was performed by comparing the EBAM simulation results with the EBAM experimental results for melt pool geometry.

To understand how to make bulk titanium parts or coatings with desired levels of titanium nitrides, this paper investigates the dynamic interactions between titanium and nitrogen under representative laser-based additive manufacturing (AM) conditions. Under a set of gas environments containing different concentrations of nitrogen, the titanium and nitrogen reaction products—formed under typical Selective Laser Melting (SLM) and Laser Engineered Net Shaping (LENS) AM scanning conditions—are examined for compositions, phases, and microstructures. In-situ synchrotron X-ray diffraction (SXRD) test is performed to reveal the high temperature reaction steps between titanium and nitrogen.

Electron Beam Additive Manufacturing (EBAM) is one of the emerging additive manufacturing (AM) technologies that is uniquely capable of making full density metallic components using layer-by-layer fabrication method. To build each layer, the process includes powder spreading, pre-heating, melting, and solidification. The thermal and material properties involved in the EBAM process play a vital role to determine the part quality, reliability, and energy efficiency. Therefore, characterizing the properties and understanding the correlations among the process parameters are incumbent to evaluate the performance of the EBAM process. In this study, a three dimensional computational fluid dynamics (CFD) model with Ti-6Al-4V powder has been developed incorporating the temperature-dependent thermal properties and a moving conical volumetric heat source with Gaussian distribution to conduct the simulations of the EBAM process. The melt-pool dynamics and its thermal behavior have been investigated numerically using a CFD solver and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and enthalpy have been obtained for a particular set of electron beam specifications.

The powder-bed electron beam additive manufacturing (EBAM) process is one of the relatively new additive manufacturing (AM) technologies in which the metal powder is melted in a vacuum environment utilizing a high-energy heat source to fabricate metallic parts in a layer by layer manner. Different metallic alloys (especially, high entropy alloys such as Ti-6Al-4V) have been widely studied as a powder-bed material for the EBAM. Despite the unique advantages of designing complex geometry and tooling-free manufacturing, there are still considerable challenges in the EBAM, e.g., obtaining desired metallurgical behavior, part accuracy, reliability, and quality consistency. Therefore, a better understanding of the thermo-fluid and mechanical properties of the EBAM process is indispensable to meet the challenges. In this study, transient computational fluid dynamics (CFD) modeling of Ti-6Al-4V melt pool has been done using ANSYS Fluent 15.0 to characterize the process parameters associated with the EBAM process including the melt pool geometry, beam power, beam speed, beam diameter, and temperature profile along the melt scan. In fact, the dynamics and the solidification of the melt pool have been investigated numerically and results for cooling rate, variation in density, pressure, velocities, and liquid fraction have been obtained to illustrate the versatility of the analysis.Copyright © 2016 by ASME

An amorphous silica (AS) replacing up to 10% of the portland cement by mass in concrete behaved partly as a traditional pozzolan, partly crystallized to quartz and the rest underwent some (crystal) structural reorganization without morphological changes. The pozzolanic behavior was evident from a reduction in the calcium hydroxide content of AS-cement paste with time. A new crystalline phase was observed in the scanning electron microscope only when AS was present, and energy dispersive X-ray microanalysis coupled with X-ray absorption near edge structure spectroscopy confirmed that it was the most stable form of silica, quartz. The presence of AS changed the concrete’s microstructure, aggregate–paste interface, and pore size distribution.

The recent appearance of several commercial systems makes X-ray microtomography (micro-CT) more accessible for laboratory testing. The current study was undertaken to assess the capabilities and limitations of micro-CT for the characterization of damage and internal flaws, including delamination and microcracking, in fiber-reinforced polymer–matrix composite materials. Samples with a variety of damage types and geometries, and of various dimensions, were investigated to assess the effect of the system resolution on the ability to determine the internal geometry of flaws. Particular attention is paid to the detection of microcracking, a subject of critical interest in the study of fiber-reinforced polymer–matrix composite laminates. The results demonstrate that X-ray microtomography can facilitate characterization of the internal geometry of flaws, including delamination, matrix cracking, and microcracking, in fiber-reinforced polymer laminates.

Electro-plasma technology (EPT) is a cathodic atmospheric plasma process which has shown great promise for the deposition of metal coatings exhibiting excellent adhesion to the substrate along with high deposition rates. The present study involves synthesis and characterization of molybdenum coatings using EPT processing. The morphology, composition and structure of Mo-coated surfaces were characterized. The results indicate the successful deposition of molybdenum, with molybdenum alloyed into the surface of both the 4330V steel and Inconel 718 substrates. The surface morphology and roughness of the coated samples reflect unique EPT-induced micro-roughness features. Superposition of the EPT-induced micro-roughness profile on the macro-roughness profile of the substrate surface provides the potential to improve adhesion characteristics of surface. An increase in hardness observed on Mo-coated steel indicates potential to produce hard surfaces by EPT, leading to many advanced applications.

X-ray absorption near-edge fine structure (XANES) analyses are carried out in order to study the local structure around a Cl atom of chloronaphthalene dissolved in the CH 3 I solution near the boiling point by use of full multiple scattering calculations. We find that less than six CH 3 I molecules surround the Cl atom at distance of about 4.73 A, which is larger than the sum of the van der Waals radii. CH 3 I molecules point their CI → vectors to the Cl atom. Other important information is the relative thermal fluctuation (Debye–Waller factor) between Cl and CH 3 I, which is quite large, ∼0.71 A. These features are essential to describe the intermolecular correlation in liquids, and are similar to those of supercritical fluids (SCFs).

Glass-coated Fe–Ni–Cu microwires prepared by Taylor's technique exhibit negative magnetoresistance (MR) of 8.15% at 77 K and 6.35% at 300 K in a magnetic field of 9.0 T. The MR is of the same origin found in the granular giant magnetoresistance (GMR) materials and is distinguishable from the giant magnetoimpedance (MI) commonly seen in soft magnetic microwires. MI displays a peak at zero field for RF currents with frequencies less than 20 MHz and it crosses over to a sharp dip at higher frequencies. This crossover is ascribed to the skin-depth-limited response primarily governed by the field dependence of the permeability. Micro-X-ray absorption near edge structure (micro-XANES) spectroscopy data were collected at the K edges of Cu, Ni and Fe and revealed that the Fe atoms in the as-cast sample are in FCC configuration and they remain in the FCC phase throughout the annealing processes. The MR decreases to ∼2.5% as the annealing temperature increases to 500°C. The loss of GMR upon annealing is attributed to the growth of FCC Fe–Ni-rich magnetic particles. The increase in the Fe–Ni particle size also results in higher room temperature coercivity. When the annealing temperature is increased to 500°C, a wasp-waisted hysteresis loop is observed which arises from the locking-in of the domain walls by the directional order of atoms due to diffusion under the influence of the local magnetic field. A magnetically hard glass-coated microwire with coercivity of 600 Oe is obtained after annealing at 700°C for 1 h.

Changes in the composition of embedded pyrite (FeS 2 ) particle electrodes in 1 M LiClO 4 propylene carbonate solutions as a function of the applied potential have been examined in situ by S K-edge fluorescence X-ray absorption near edge structure (XANES), using a specially designed cell that minimizes attenuation of low energy X-rays. Pyrite electrodes that had been scanned from 3.0 V versus Li/Li + , i.e. close to the open circuit voltage, down to 1.0 V (fully discharged state, i.e. 4e − -reduction) and then half recharged (2e − -reoxidation) by scanning the potential in the positive direction up to 2.2 V versus Li/Li + , revealed features consistent with the presence of Li 2 FeS 2 , in agreement with in situ Fe K-edge results reported earlier by this research group. Moreover, only subtle changes were discerned between the in situ S K-edge XANES of the half-, and fully-recharged electrodes. This close resemblance may reflect similarities between the spectral signatures of Li 2 FeS 2 and Fe 1− x S (pyrrhotite), which is the main product of the discharge reaction. Evidence for the formation of elemental sulfur and Li 2 S, which are believed to be minor products of the reaction, was obtained from analysis of the first differential S XANES and selected difference spectra. The compositional variations of the embedded pyrite particles throughout the course of the electrochemical processes occur in the presence of a persistent sulfate coating.

Electro-plasma cleaning and deposition (EPCAD) is a recently developed electrolytic process for cleaning mill scale and other impurities from newly manufactured steel. The process offers reduced costs, improved coating adhesion, and increased corrosion resistance as potential benefits. Test samples of A-36 mild steel were cleaned using the EPCAD process and an industrial wheelabrator unit. Surface profile measurements and scanning electron microscopy were performed on both sets of samples to investigate the respective surface morphologies. Cleaned samples were then coated with an inorganic ceramic-based zinc primer. Tensile adhesion tests were performed and showed comparable adhesion properties for the EPCAD-cleaned and shot-blasted samples. The favorable adhesion properties are attributed to the microroughness and unique surface morphology produced by the EPCAD process.

OBJECTIVES We sought to determine motivating factors for radiation oncologists to form joint ventures with urologists to provide intensity modulated radiation treatment (IMRT) to prostate cancer patients that the urologists diagnose. METHODS The American College of Radiation Oncology developed a survey and requested responses from radiation oncologists who had professional relationships with urologists to deliver prostate cancer intensity modulated radiation treatment in a combined practice. Daily patient treatment totals and practice characteristics were queried. To date, there is no actual data to elucidate the motivation of radiation oncologists to form such an association. RESULTS All 75 respondents indicated that their practice model was a multispecialty group, in which the radiation oncologist has an employment agreement to receive the professional component for radiation treatment services, and was also a financial partner in the technical component. All respondents were economically displaced in a geographic region by existing radiation oncology groups, hospital-based radiation oncology practice, or both. All radiation oncologist respondents stated that they were unable to achieve professional partnership status within a radiation oncology group, and 98.6% were unable to obtain a share of the technical component for radiation treatment. Eighty-six percent of respondents treated patients with nonprostate malignancies in their facility, at a rate of 1.9 times more nonprostate patients than prostate patients. CONCLUSION This data may indicate that radiation oncologists combine with urologists in a geographic area where the radiation oncologist has been economically displaced, has existing referral patterns, and continues to treat other patients with nonprostate malignancies.

This paper describes a method for conducting the structural dynamic analysis of a crane fly (family Tipulidae) forewing. Wing geometry is captured via microcomputed tomography (micro-CT) scan. A finite element (FE) model of the forewing is developed from the reconstructed model of the micro-CT scan to determine the natural frequencies and mode shapes of the wing in vacuum. The FE model is validated by comparing the first three natural frequencies of a tubular cantilever beam with similar dimensions and properties of a vein of the wing to the analytical solution obtained from Euler beam theory. The natural frequency of the wing increases with mode in vacuum. The first three mode shapes of the wing are characterized by bending and torsional deformation responses. Furthermore, a simulation of the fluid-structure interaction (FSI) of the forewing under steady and unsteady conditions at low freestream velocities, similar to those encountered by insects in regular flight, is performed by coupling the FE model of the wing with a computational fluid dynamics model. For steady air flow, the FSI simulations reveal that high magnitude deformation regions develop at the center of the wing and that the deformation increases nonlinearly with increasing freestream velocity. For unsteady air flow, a more uniform deformation distribution is observed along the span wise direction of the wing.

Vapor quenching in the phase-separating Ag-Ni system creates alloys that appear homogeneously amorphous under conventional probes. However, an atomic-level structural analysis based on extended x-ray absorption fine structures in combination with reverse Monte Carlo and molecular dynamics simulations demonstrates that these new phases are characterized by nonuniform, spinodal-like structures on an extremely fine scale. This heterogeneous nature of the structure is directly responsible for the unexpectedly low heat (and temperature) of crystallization observed in calorimetric measurements.

While many binary systems exhibit a positive heat mixing that precludes intermixing in conventional bulk diffusion couples, it is possible to alloy in solid state some of these bulk immiscible elements in nanostructures. Molecular dynamics simulations demonstrate that in low-dimensional systems such as surfaces and in sub-nanometer layered superlattice structures, excess enthalpic and entropic energy contributions can provide a driving force for spontaneous intermixing to form substitutional solid solution alloys. Such driving forces diminish, however, in coarser nanophase binary mixtures when domain sizes reach beyond ≈1 nm. In this case, true alloying on the atomic level can be achieved by employing an external forcing mechanism such as severe mechanical deformation. In addition to single-phase alloys, we demonstrate, using X-ray absorption near-edge structure (XANES) analysis, a novel two-phase coexistence controlled by kinetically imposed polymorphic constraints. Using a phenomenological model, possible mechanisms responsible for driven alloying are discussed with reference to several previous proposals in the literature.

Porous silica gels have been prepared by the sol–gel method using tetraethoxysilane (TEOS), ethanol and water with two dopants, CuCl and CuSO 4 , with different copper contents (1 and 5 mol%). The samples were prepared as monolithic shapes, dried at 110°C for 24 h and heat treated at 500, 900 and 1100°C. Their structural evolution was studied by gas absorption, X-ray diffraction and X-ray absorption spectroscopy. All samples showed a stable structure of pores up to 900°C and a strong densification process at 1100°C. For temperatures lower than 500°C, an amorphous material was formed, and the crystalline phases of cristobalite, quartz, cuprite and tenorite were determined after heat treatment at 900°C. CuO was formed in the pores of samples doped with CuCl heated at 900 and 1100°C. In the pores of samples doped with CuSO 4 , CuO was formed at 900°C and Cu 2 O at 1100°C.

Dust from production of steel in an electric arc furnace (EAF) contains a mixture of elements that pose a challenge for both recovery and disposal. This paper relates the leachability of six Canadian EAF dusts in four leaching tests [distilled water, Ontario Regulation 347 Leachate Extraction Procedure, Amount Available for Leaching (AALT), and pH 5 Stat] to their mineralogy. Chromium and nickel contaminants in EAF dust are largely unleachable (

To date, the exact nature of the plasma nitriding mechanism and the role of energetic particle bombardment are not well understood. The purpose of this work has been to obtain a more detailed knowledge about the evolution of the plasma nitrided surface layer as a function of the energy of the bombarding particles. Nitrided layers were produced at the surface of pure titanium specimens at various flux energies by Intensified Plasma-Assisted Processing (IPAP), a triode plasma technique developed in our laboratory. X-ray Absorption Near Edge Structure (XANES) spectroscopy and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy were used to characterize the local structure of the titanium nitride layers. Cross sections of the processed specimens were studied by Auger electron spectroscopy and electron microscopy. The results showed that increasing flux energy promotes the formation of a well-ordered TiN layer at the surface. Low flux energies produce significantly lower fractions of the TiN phase at the surface, as well as thinner nitrided layers. A structural model was suggested and quantitatively tested based on the XANES and EXAFS measurements.

X-ray absorption spectroscopy (XAS) measurements were performed at the Fe K edge to determine the iron local structure in chemically prepared polyaniline (PANI) and polypyrrole (PPy) samples prepared with FeCl3 as an oxidant. The samples were conditioned at different pHs by an acid–base treatment. In both as synthesized-doped polymers, the observed dispersed Fe atoms were predominantly coordinated to chlorine as Fe(III)Clx species, where x=6 for PANI and x=4 for PPy samples suggesting that the polymer–counteranion bonding is weaker than the iron–chelate one. For the PANI samples submitted to basic treatment, three different sets of Fe distances were found: five Fe–O at 2.00 A, three Fe–Fe at approximately 2.80 A and five Fe–Fe at 3.00 A and the near-edge spectra showed the presence of octahedrally coordinated Fe+3. These results strongly suggest the presence of small oxide/hydroxide aggregates. Similar data were obtained for PPy treated with NH4OH.

A new technique using the X-ray absorption near-edge structure (XANES) has been developed to simultaneously determine the compositions and phase fractions of the two coexisting (f.c.c. and b.c.c.) supersaturated solid solutions in mechanically alloyed Cu 100− x Fe x ( x =50–80) formed by ball milling under cryogenic conditions. The XANES analysis indicates that throughout this region the two coexistent phases have almost identical composition, consistent with that of the overall mixture. This represents a novel two-phase coexistence representing a region of overlap in solubility rather than the normal miscibility gap. A mechanism is proposed to explain the nature of this two-phase region in terms of extended solubility induced by ball milling, the free energies of the two phases including defect enthalpies, and nucleation and growth barriers for the b.c.c.–f.c.c. (and f.c.c.–b.c.c.) transformation.

The local structures of ‘host’ and ‘guest’ layers of MoS2 intercalated with M(OH)2 (MMn, Co and Ni) prepared via interaction of single-layer MoS2 dispersions and solutions of M2+ salts were studied by X-ray absorption spectroscopy. According to M K-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) results, the electronic structure and atomic environment of the M atoms in the intercalates are similar to that of the crystalline hydroxides M(OH)2. In the Ni intercalate, Mo K-edge EXAFS revealed a structural change of the ‘host’ MoS2 layers similar to that reported for water dispersions of MoS2 single layers. S K-edge XANES data indicate that the change is associated with increased electron density on the S atoms in the matrix. SO42− and Mo″− (4

Extended x-ray-absorption fine-structure analysis demonstrates that the Cu-Fe and Ag-Fe systems, both immiscible in equilibrium, exhibit contrasting alloying behavior when subjected to mechanical milling. While Cu-Fe undergoes atomic-level alloying forming solid solutions, Ag-Fe remains largely unreacted. The alloying behavior observed is explained based on a model for a dynamic system, combining both the effects of externally driven mixing and thermal evolution under the thermodynamic driving force prevailing in a ball-milled mixture.