Electron Backscatter Diffraction Orientation Research Articles

Microstructural analysis of titanium alloys based on high-temperature phase reconstruction

AbstractThe microstructural evolution of titanium alloys under high-temperature conditions plays a key role in determining their mechanical properties and hot working behavior. This research presents an advanced method for calibrating β phase reconstruction software using in situ testing on Grade 2 titanium, which achieves accurate reconstruction of the parent β phase microstructure. In addition, unique microstructural observations in the forging of Ti-6246 titanium alloy are highlighted, demonstrating the influence of deformation parameters on the resulting β phase grain structures. Using advanced techniques such as electron backscatter diffraction and Burgers orientation relationship-based software, the research elucidates the behavior of these phases under varying thermal and deformation conditions. In Grade 2 titanium, significant grain growth and phase transformation dynamics were observed upon heating beyond the β-transus temperature during in situ calibration of β phase reconstruction software. The analysis demonstrates the effectiveness of the software in precise reconstructing the parent β phase microstructure based on the orientation of the inherited αs phase. Furthermore, the evaluation of hot forming parameters in Ti-6246 alloy shows the influence of deformation temperature and strain rate on the resulting microstructure. Finite element method analysis coupled with dynamic material modeling elucidates the distribution of temperature, strain rate, and effective strain during forging, which aids in the qualitative assessment of hot workability. Microstructural observations in Ti-6246 alloy forging highlight the presence of elongated colonies of αs phase precipitates, indicative of localized strain intensities and deformation temperatures. In addition, EBSD analysis coupled with β phase reconstruction reveals distinct microstructural features in different regions of the forging. In particular, regions subjected to higher strain rates exhibit elongated β phase grains with pronounced disorientation gradients, suggesting intense deformation. Conversely, optimal forging conditions lead to the appearance of unreinforced axisymmetric β phase grains, indicating dynamic recovery processes. Pole figure analysis further emphasizes the Burgers crystallographic relationship between the αs and β phases, confirming that deformation during forging occurs exclusively within the β phase. These results provide valuable insights into the microstructural evolution in titanium alloys under high-temperature conditions, which are essential for optimizing hot working processes and improving mechanical properties. Graphical abstract

Functional LSMO foams for magneto-caloric applications

The ferromagnetic La1-x\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{1-x}$$\\end{document}Srx\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{x}$$\\end{document}MnO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_3$$\\end{document} (LSMO) manganites are ideal materials for magneto-caloric applications due to their high Curie temperature. Here, we prepare open-cell, porous LSMO foams starting from a commercial polyurethane (PU) foam and commercial LSMO powder with x=0.3.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$x = 0.3.$$\\end{document} The cut PU foams are then covered by a slurry of LSMO powder mixed with PVA and water, and then, the foams are subjected to a heat-treatment with two steps at 600 ∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}C (burn-off organic material) and 1200 ∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}C (sintering/compacting). The resulting ceramic LSMO foams are then characterized by X-ray, SEM, electron backscatter diffraction (EBSD) orientation mapping and magnetic measurements. The foam sample consists of randomly-oriented LSMO grains with an average grain size of 188 nm, being distinctly smaller than bulk samples of the same composition, but considerably larger than LSMO nanowires prepared by electrospinning. The magnetic data reveal a high Curie temperature like the bulk samples, and an entropy change, -ΔSM\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-\\Delta S_{\ ext{M}}$$\\end{document} slightly higher than that of the bulk samples, which points to a strong influence of the LSMO grain size. Thus, the resulting LSMO foam material is well suited for magneto-caloric applications at room temperature.

Retained austenite grain size as a strength-plasticity relationship indicator in Al-alloyed medium-Mn steel processed by intercritical annealing

Although most studies focus on the impact of the fraction of retained austenite (RA) on the relationship between strength and plasticity, this research explores the influence of the mechanical stability of RA, which is primarily affected by its grain size. To investigate this, samples of 5% Mn steel with varying fractions of RA, as well as different sizes and concentrations of carbon (C) and manganese (Mn), were produced by adjusting the soaking time during intercritical annealing (IA) between 1 and 300 min at a temperature of 680 °C. The mechanical properties of the samples were evaluated using static tensile tests. Detailed microstructural analyses were conducted before and after deformation through hardness tests, X-ray diffraction measurements (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) images, TEM-EDS microanalysis, and electron backscatter diffraction (EBSD) phase and orientation maps. Additionally, thermodynamic calculations were used to supplement the experimental findings. The results suggest that both chemical enrichment and grain size reduction have comparable effects on stabilizing the RA. The wide variation of RA grain sizes from 0.02 to 0.15 μm3 promotes a gradual and continuous martensitic transformation under strain throughout the entire strain range, leading to a uniform elongation exceeding 19% in the steel analyzed. However, the presence of an appropriate average size of RA (from ∼0.07 to ∼0.11 μm3) is crucial because grains smaller than ∼0.02 μm3 impede martensitic transformation, while coarse grains characterized by a volume greater than ∼0.13 μm3 result in significant transformation in an early stage of deformation.

Adaptable physics-based super-resolution for electron backscatter diffraction maps

In computer vision, single-image super-resolution (SISR) has been extensively explored using convolutional neural networks (CNNs) on optical images, but images outside this domain, such as those from scientific experiments, are not well investigated. Experimental data is often gathered using non-optical methods, which alters the metrics for image quality. One such example is electron backscatter diffraction (EBSD), a materials characterization technique that maps crystal arrangement in solid materials, which provides insight into processing, structure, and property relationships. We present a broadly adaptable approach for applying state-of-art SISR networks to generate super-resolved EBSD orientation maps. This approach includes quaternion-based orientation recognition, loss functions that consider rotational effects and crystallographic symmetry, and an inference pipeline to convert network output into established visualization formats for EBSD maps. The ability to generate physically accurate, high-resolution EBSD maps with super-resolution enables high-throughput characterization and broadens the capture capabilities for three-dimensional experimental EBSD datasets.

Eutectic growth kinetics and microscopic mechanical properties of rapidly solidified CoCrFeNiMo0.8 high entropy alloy

Liquid CoCrFeNiMo0.8 high entropy alloy (HEA) was undercooled by up to 205 K and thus rapidly solidified with electromagnetic levitation technique. A kinetics transition from slow lamellar eutectic growth to rapid anomalous eutectic growth was observed, which showed a significant effect on crystal orientation and mechanical properties. At small undercoolings below 89 K only (σ-CrFeMo + FCC) lamellar eutectic growth proceeded. Once the undercooling exceeded this threshold, anomalous eutectic would grow directly and lead to an extra recalescence peak. The maximum growth velocity of lamellar eutectic was measured as 0.012 m s−1, whereas that of anomalous eutectic attained 2.547 m s−1 at the largest undercooling of 205 K. It was revealed that the eutectic growth mechanism transition resulted from the independent nucleation and cooperative branched growth of the two eutectic phases. An orientation relationship (OR) of {110}σ // {111}FCC and <111>σ // <110>FCC was determined between σ-CrFeMo and FCC phases by electron backscatter diffraction (EBSD) orientation analysis. Furthermore, mechanical measurements indicated that the hardness, compression strength and ductility of this HEA showed an increasing trend with the rise of liquid undercooling, which may be attributed to structural refinement and the volume fraction increase of anomalous eutectic.

Texture in cold rolled and high-temperature annealed Cu foils

Thick single crystal Cu foil substrates with specific crystallographic orientations such as {111} and {110} planes parallel to the rolling plane are desired for epitaxial growth of two-dimensional materials such as graphene. In this study, annealing experiments of a 46 μm thick cold-rolled foil were carried out at temperatures in the range of 300-1040 °C. The texture evolution during annealing was followed by electron backscatter diffraction (EBSD) orientation mapping. It was found that the texture evolution may be divided into three stages: at relatively low annealing temperatures, a strong cube texture develops with a small population of grains having relatively larger deviations from the cube orientation; at medium temperatures, these grains with large deviations grow abnormally; and at the highest temperature, annealing twins form in the abnormally growing grains giving rise to new orientations including some with the {111} planes parallel to the rolling plane.

Effect of the anisotropy of martensitic transformation on ferrite deformation in Dual-Phase steels

The volume increase and shape change during austenite to martensite transformation in dual-phase (DP) steels are largely accommodated in the microstructure by the deformation of the surrounding ferrite matrix. Accurate estimation of transformation-induced deformation of ferrite via experiments and modeling is essential for predicting the subsequent mechanical behavior of DP steels. This study aims to illustrate the disadvantages of simplifying the anisotropic transformation deformation of martensite to isotropic dilatation for modeling the transformation-induced deformation of ferrite. A novel methodology is developed comprising sequential experimental and numerical research on DP steels to quantify transformation-induced strains in ferrite. This methodology combines the results of prior austenite grain reconstruction, phenomenological theory of martensite crystallography and electron backscatter diffraction (EBSD) orientation data to estimate variant-specific transformation deformation. Subsequently, by comparison of full-field micromechanical calculation results on a virtual DP steel microstructure with experimental EBSD kernel average misorientation and geometrically necessary dislocation measurement results it is shown that neglecting the shear deformation associated with the martensitic transformation leads to significant underestimation in the prediction of transformation-induced strains in ferrite.

Effect of microstructure heterogeneity on the mechanical properties of friction stir welded reduced activation ferritic/martensitic steel

The microhardness distribution in the different zones of a friction stir welded reduced activation ferritic/martensitic steel has been investigated and correlated to the hierarchical martensitic microstructure in the respective zones, characterized by electron backscatter diffraction orientation analysis. It is found that the variation of prior austenite grain size, packet size, and block width in different subzones is influenced by the peak temperature and effective strain rate during the friction stir welding process. The distribution of the microhardness correlates directly with the geometrically necessary dislocation density observed in the different zones.

Microstructural and mechanical characterization of a shot peening induced rolled edge on direct aged Inconel 718 alloy

Shot peening of complex geometries can generate rolled edges which mechanical properties, compared to a flat shot peened specimen, are not well known. Electron BackScattered Diffraction (EBSD) analyses and nanoindentation tests were conducted to characterize the microstructural changes and hardening induced in the rolled edge compared to a reference flat part of an Inconel 718 direct aged specimen. Dictionary Indexing was used to improve the indexation quality in zones presenting severe plastic deformations. Geometrically necessary dislocation densities were estimated from the EBSD orientation maps and correlated with the nanoindentation measurements using a Taylor hardening model. The rolled edge zone presented 1 GPa higher hardening values and a steeper hardening gradient as compared with the reference. This was mainly attributed to work hardening, due to higher dislocation densities around the rolled edge. Such differences could result from a pure shear state induced by bending of the surface close to the sample's border during the rolled-edge formation.

The effect of laser scanning strategies on the microstructure, texture and crystallography of grains exhibiting hot cracks in additively manufactured Hastelloy X

In the present study, grain size and grains exhibiting hot cracks of laser powder bed fusion (LPBF) processed Hastelloy X as-built parts under two scanning strategies i.e., 90° and 45° rotation vectors have been characterized using electron back scattered diffraction (EBSD) technique. EBSD orientation maps revealed relatively finer grain size in 45° scanning strategy as compared to 90° scanning strategy. Laser scanning speed was found to be the governing parameter for variation in grain size as compared to laser power and energy density. Maximum crack density was observed at the highest value of energy density and it appears that energy density has more dominant effect on hot cracking tendency as compared to laser power. At the maximum value of the energy density under 45° scanning strategy, the preferred texture type changes from <001> to <111> orientation. EBSD orientation maps revealed that a specific combination of grains, one of which is stiffer as compared to other, is more susceptible for hot cracks. They are either Goss ({110}<001>), Brass ({110}<112>) or Copper ({112}<111>) oriented grains. It is proposed that these stiffer grains, with high elastic modulus and low capacity of tolerating higher magnitude of thermal strains, paves the way for relieving locked-in thermal stresses during LPBF process.

Issue Information

Cover Photograph: Electron backscatter diffraction (EBSD) orientation mapping of the a Y2O3 sample surface before the plasma exposure and the corresponding atomic force microscopy (AFM) topography at the same position after the plasma exposure for 2 h at a bias voltage of 150 V highlighting an orientation dependent erosion mechanism. Credit: Egbert Wessel, Nino Schön and Moritz Kindelmann. [https://doi.org/10.1111/jace.17556] image 2020 ACerS Ceramographic Exhibit &amp; CompetitionCategory: Undergraduate, 1st Place Winner Snow Award image

Local initial heteroepitaxial growth of diamond (111) on Ru (0001)/c-sapphire by antenna-edge-type microwave plasma chemical vapor deposition

Heteroepitaxial growth is critical for large-scale synthesis of diamond (111) substrates. In this study, the local initial epitaxial growth of diamond (111) on Ru/c-sapphire was investigated. As the economic viability of ruthenium (Ru) is more than that of iridium (Ir), a 150-nm Ru (0001) thin film was sputter-deposited on an Al2O3 (0001) substrate using a RF/DC magnetron sputtering system. X-ray diffraction analyses of the Ru film revealed the (0001) phase orientation with high crystalline quality. Both bias-enhanced nucleation and initial heteroepitaxial growth of diamond were realized via antenna-edge-type microwave plasma chemical vapor deposition. After 30 min of heteroepitaxial growth, the crystallite (diameter ∼500 nm) with a smooth surface was observed through scanning electron microscopy. Electron backscattering diffraction (EBSD) orientation mapping indicated the presence of the highly oriented diamond (111) crystallite. The epitaxial orientations between diamond (111) and Ru were determined as [111]diamond//[0001]Ru and [112¯]diamond//[101¯0]Ru. The EBSD pole-figure pattern represented the formation of a double positioning defect. This study demonstrated the feasibility of heteroepitaxial growth of diamond (111) on Ru, which provides a more economically viable approach to fabricating large-size diamond substrates.

Fatigue life enhancement in alpha/beta Ti–6Al–4V after shot peening: An EBSD and TEM crystallographic orientation mapping study of surface layer

Shot peening is a well-established surface treatment technique to improve metallic components’ fatigue lives by introducing compressive residual stress at their surface layers. Using α/β Ti–6Al–4V alloy as an example, the fatigue life of Ti64 was significantly enhanced after a compressive residual stress was introduced to a depth of 208 µm via shot peening treatment. The top ~24 µm layer from surface was found interestingly unable to be indexed under electron backscatter diffraction (EBSD), a depth coinciding with the presence of maximum compressive residual stress as revealed by center hole drilling method. Transmission electron microscope (TEM) with crystallographic orientation mapping was therefore employed to probe the top surface layer in order to unveil the origin of such thick non-indexed region observed in EBSD after shot peening and its effect on enhancement of component's fatigue life.

EBSD orientation analysis based on experimental Kikuchi reference patterns

Orientation determination does not necessarily require complete knowledge of the local atomic arrangement in a crystalline phase. We present a method for microstructural phase discrimination and orientation analysis of phases for which there is only limited crystallographic information available. In this method, experimental Kikuchi diffraction patterns are utilized to generate a self-consistent master reference for use in the technique of Electron Backscatter Diffraction (EBSD). The experimentally derived master data serves as an application-specific reference in EBSD pattern matching approaches. As application examples, we map the locally varying orientations in samples of icosahedral quasicrystals observed in a Ti40Zr40Ni20 alloy, and we analyse AlNiCo decagonal quasicrystals.

On the evolution of mechanical properties and microstructure of ferritic-bainitic (FB) 2.25Cr-1Mo (Grade 22) steel during high-temperature creep

The development of creep damage in ferritic-bainitic 2.25Cr-1Mo (Grade 22) steel was studied by following the evolution of mechanical properties and microstructure by characterisation of a series of interrupted creep specimens (605 °C/80 MPa). The change in mechanical properties of the partially crept specimens was evaluated via hardness measurements, while the microstructural changes were characterized by a range of microscopy techniques. The nano-hardness measurements combined with a statistical analysis allowed for analysis of the strength of the present constitutive phases as a function of creep time (tc), and imparted creep strain (ɛc). In addition, a machine learning methodology was used to identify ferrite and bainite regions in Electron Back-Scatter Diffraction (EBSD) orientation maps, which then allowed for a study of the evolution of dislocation densities (Geometrically-Necessary Dislocations, GNDs) in each phase separately. It is shown that the amount of GNDs in the bainite is reduced significantly during the high-temperature creep, while there is a moderate increase in the amount of GNDs in ferrite grains. These trends are consistent with the observed changes in the strength (hardness) of each phase – bainite is significantly softening, while ferrite slightly hardening. The reduction of the amount of dislocations in the bainite and its consequent softening is caused by the progressive decomposition of the needle-like bainite present in the initial microstructure into polygonal fine-grained ferrite-like bainite. Transmission electron microscopy (TEM) confirmed the changes in dislocation density observations and was also used to identify changes in carbides during the high-temperature creep.

Correlative microscopy for quantification of prior austenite grain size in AF9628 steel

The characterization of prior austenite grain size is important for an understanding of the microstructure-property relationships in steels. In this study, the prior austenite grain boundaries (PAGBs) were delineated in a low alloy high performance steel, AF9628, with two different methods: (i) conventional approach via etching, followed by optical or scanning electron microscopy, and (ii) analysis of electron backscattered diffraction (EBSD) data. Correlative microscopy was employed to obtain images of the same region of the specimens with the two independent methods. The threshold method of delineating PAGBs in EBSD orientation maps revealed a large fraction of the PAGBs that were delineated by the conventional approach. However, many PAGBs were not delineated in the EBSD maps. On the other hand, the twin boundaries within the prior austenite grains were not delineated by the conventional approach and many of these boundaries were delineated in the EBSD maps. The net result was that the measurements on EBSD orientation maps resulted in an overestimation of the prior austenite lineal intercept grain size by approximately 21% and an underestimation of the surface area of PAGB per unit volume of material (SV) by approximately 17%. The errors in the measurements on the EBSD orientation maps were discussed in the context of the probability density function for misorientation angles in cubic metals (i.e., Mackenzie plot), which suggests that the overestimation in the prior austenite grain size measurement would be expected to be even higher (specifically 47%) for the general case of random texture of prior austenite grains with no twins. In view of the results of this study, it is suggested that the use of threshold method for delineating PAGBs and determining prior austenite grain size or SV may be sufficient for examining relative trends, for example, as a result of heat treatments. However, the conventional methods to delineate the PAGBs may be required when quantitative values of microstructural parameters are of interest.

Visualization of the grain structure in the filament cross sections of uniaxially textured high J c Bi-2223 tapes

In this study, we extensively used electron backscatter diffraction orientation imaging microscopy to visualize the grain structure in the flat-rolled (Bi,Pb)2Sr2Ca2Cu3O x (Bi-2223) tapes. The thermomechanical process made the grains’ c-axes oriented normal to the tape surface. The 24% difference in critical current density J c was caused by the ∼5° difference in the degree of out-of-plane texture. Although the in-plane orientations are not controlled, the Bi-2223 grains can form the domains, each of which consists of the grains with similar in-plane orientation. Controlling the domain formation could be the next protocol to raise the J c of Bi-2223 tapes.

On the Evolution of Mechanical Properties and Microstructure of Ferritic-Bainitic (FB) 2.25Cr-1Mo (Grade 22) Steel During High-Temperature Creep

The development of creep damage in ferritic-bainitic 2.25Cr-1Mo (Grade 22) steel was studied by following the evolution of mechanical properties and microstructure by characterisation of a series of interrupted creep specimens (605 °C/80 MPa). The change in mechanical properties of the partially crept specimens was evaluated via hardness measurements, while the microstructural changes were characterized by a range of microscopy techniques. The nano-hardness measurements combined with a statistical analysis allowed for analysis of the strength of the present constitutive phases as a function of creep time (tc), and imparted creep strain (ec). In addition, a machine learning methodology was used to identify ferrite and bainite regions in Electron Back-Scatter Diffraction (EBSD) orientation maps, which then allowed for a study of the evolution of dislocation densities (Geometrically-Necessary Dislocations, GNDs) in each phase separately. It is shown that the amount of GNDs in the bainite is reduced significantly during the high-temperature creep, while there is a moderate increase in the amount of GNDs in ferrite grains. These trends are consistent with the observed changes in the strength (hardness) of each phase - bainite is significantly softening, while ferrite slightly hardening. The reduction of the amount of dislocations in the bainite and its consequent softening is caused by the progressive decomposition of the needle-like bainite present in the initial microstructure into polygonal fine-grained ferrite-like bainite. Transmission electron microscopy (TEM) confirmed the changes in dislocation density observations and was also used to identify changes in carbides during the high-temperature creep.

Study on Bainite/Martensite Transformation in Reheated Weld Metals

A new combination of laser scanning confocal microscope (LSCM) and electron backscattering diffraction (EBSD) with a field-emission scanning electron microscope (SEM) is utilized to study the mechanism of bainite transformation in reheated low carbon bainitic weld metal. The LSCM observations show that laths grow on the surface at various rates, from 30 μm/s to 240 μm/s, which is greatly larger than those referred in literature for bainite. In order to confirm that the laths are bainite and not surface martensite, additional experiments were performed. The crystallographic characteristics of surface bainite were compared with those of bulk bainite obtained during isothermal treatments and those of bulk martensite obtained by water quenching. By means of a dedicated EBSD data-treatment software, orientation relationship, variant selection and packet groups were identified; it was shown that both the surface laths and bulk bainite share the same misorientation, habit plane, and have similar variant distribution. Experiments are running to compare these features with those of bulk martensite. If the distinction between martensite and bainite is successful, the very high growth rates of the surface laths could be used to discuss the displacive/diffusive nature of bainitic transformations.

Microstructural constraints on magma emplacement and sulfide transport mechanisms

The poorly constrained nature of the physical transfer of sulfides along magmatic conduits has implications for the genesis and localization of mineral deposits as well as for understanding the large-scale mobility of volatiles and metals across different geochemical reservoirs. Our natural laboratory to address this topic is a sulfide-bearing ultramafic pipe emplaced in the deep crust of the Ivrea-Verbano Zone, northwest Italy. The pipe comprises a volatile-rich peridotite, that contains disseminated, blebby and semi-massive sulfides enriched in nickel, copper and platinum-group elements. The integration of electron backscatter diffraction orientation data and 3D X-ray computed tomography analyses from this study indicate that 1) most of olivine crystallized upon emplacement of the magma; and 2) the shape and texture of the intra-granular sulfide blebs principally hosted within the central portions of the pipe reflect early sulfide saturation and 3) that marginal areas 1recorded higher strain compare to the cores of the pipes. The differences in the size distribution of the sulfide grains between the central and marginal areas of the pipe are due to magma emplacement dynamics. The larger sulfide aggregates forming the bulk of the Ni-Cu-PGE sulfide mineralization along the margins of the pipe are interpreted to form by coalescence of a large number of smaller sulfide droplets. The observed sulfide size distribution between the central and marginal areas of the Valmaggia pipe is principally due to the dynamics of the magma upon emplacement, and locally record the role of water- and carbon dioxide-bearing volatiles in the physical entrainment of dense sulfide liquids. These processes provide a viable mechanism to transport sulfides enriched in chalcophile and siderophile metals from the upper mantle into the lower continental crust, where they may be available for later remobilization into ore systems that may form subsequently in the middle and upper crust.