Additive manufacturing of metallic components – Process, structure and properties

Porphyry Cu systems host some of the most widely distributed mineralization types at convergent plate boundaries, including porphyry deposits centered on intrusions; skarn, carbonate-replacement, and sediment-hosted Au deposits in increasingly peripheral locations; and superjacent high- and intermediate-sulfidation epithermal deposits. The systems commonly define linear belts, some many hundreds of kilometers long, as well as occurring less commonly in apparent isolation. The systems are closely related to underlying composite plutons, at paleodepths of 5 to 15 km, which represent the supply chambers for the magmas and fluids that formed the vertically elongate (>3 km) stocks or dike swarms and associated mineralization. The plutons may erupt volcanic rocks, but generally prior to initiation of the systems. Commonly, several discrete stocks are emplaced in and above the pluton roof zones, resulting in either clusters or structurally controlled alignments of porphyry Cu systems. The rheology and composition of the host rocks may strongly influence the size, grade, and type of mineralization generated in porphyry Cu systems. Individual systems have life spans of ~100,000 to several million years, whereas deposit clusters or alignments as well as entire belts may remain active for 10 m.y. or longer.

The alteration and mineralization in porphyry Cu systems, occupying many cubic kilometers of rock, are zoned outward from the stocks or dike swarms, which typically comprise several generations of intermediate to felsic porphyry intrusions. Porphyry Cu ± Au ± Mo deposits are centered on the intrusions, whereas carbonate wall rocks commonly host proximal Cu-Au skarns, less common distal Zn-Pb and/or Au skarns, and, beyond the skarn front, carbonate-replacement Cu and/or Zn-Pb-Ag ± Au deposits, and/or sediment-hosted (distal-disseminated) Au deposits. Peripheral mineralization is less conspicuous in noncarbonate wall rocks but may include base metal- or Au-bearing veins and mantos. High-sulfidation epithermal deposits may occur in lithocaps above porphyry Cu deposits, where massive sulfide lodes tend to develop in deeper feeder structures and Au ± Ag-rich, disseminated deposits within the uppermost 500 m or so. Less commonly, intermediate-sulfidation epithermal mineralization, chiefly veins, may develop on the peripheries of the lithocaps. The alteration-mineralization in the porphyry Cu deposits is zoned upward from barren, early sodic-calcic through potentially ore-grade potassic, chlorite-sericite, and sericitic, to advanced argillic, the last of these constituting the lithocaps, which may attain >1 km in thickness if unaffected by significant erosion. Low sulfidation-state chalcopyrite ± bornite assemblages are characteristic of potassic zones, whereas higher sulfidation-state sulfides are generated progressively upward in concert with temperature decline and the concomitant greater degrees of hydrolytic alteration, culminating in pyrite ± enargite ± covellite in the shallow parts of the litho-caps. The porphyry Cu mineralization occurs in a distinctive sequence of quartz-bearing veinlets as well as in disseminated form in the altered rock between them. Magmatic-hydrothermal breccias may form during porphyry intrusion, with some of them containing high-grade mineralization because of their intrinsic permeability. In contrast, most phreatomagmatic breccias, constituting maar-diatreme systems, are poorly mineralized at both the porphyry Cu and lithocap levels, mainly because many of them formed late in the evolution of systems.

Porphyry Cu systems are initiated by injection of oxidized magma saturated with S- and metal-rich, aqueous fluids from cupolas on the tops of the subjacent parental plutons. The sequence of alteration-mineralization events charted above is principally a consequence of progressive rock and fluid cooling, from >700° to <250°C, caused by solidification of the underlying parental plutons and downward propagation of the lithostatic-hydrostatic transition. Once the plutonic magmas stagnate, the high-temperature, generally two-phase hyper-saline liquid and vapor responsible for the potassic alteration and contained mineralization at depth and early overlying advanced argillic alteration, respectively, gives way, at <350°C, to a single-phase, low- to moderate-salinity liquid that causes the sericite-chlorite and sericitic alteration and associated mineralization. This same liquid also causes mineralization of the peripheral parts of systems, including the overlying lithocaps. The progressive thermal decline of the systems combined with synmineral paleosurface degradation results in the characteristic overprinting (telescoping) and partial to total reconstitution of older by younger alteration-mineralization types. Meteoric water is not required for formation of this alteration-mineralization sequence although its late ingress is commonplace.

Many features of porphyry Cu systems at all scales need to be taken into account during planning and execution of base and precious metal exploration programs in magmatic arc settings. At the regional and district scales, the occurrence of many deposits in belts, within which clusters and alignments are prominent, is a powerful exploration concept once one or more systems are known. At the deposit scale, particularly in the porphyry Cu environment, early-formed features commonly, but by no means always, give rise to the best ore-bodies. Late-stage alteration overprints may cause partial depletion or complete removal of Cu and Au, but metal concentration may also result. Recognition of single ore deposit types, whether economic or not, in porphyry Cu systems may be directly employed in combination with alteration and metal zoning concepts to search for other related deposit types, although not all those permitted by the model are likely to be present in most systems. Erosion level is a cogent control on the deposit types that may be preserved and, by the same token, on those that may be anticipated at depth. The most distal deposit types at all levels of the systems tend to be visually the most subtle, which may result in their being missed due to overshadowing by more prominent alteration-mineralization.

Porphyry Copper Systems

The current understanding of the fundamentals of recrystallization is summarized. This includes understanding the as-deformed state. Several aspects of recrystallization are described: nucleation and growth, the development of misorientation during deformation, continuous, dynamic, and geometric dynamic recrystallization, particle effects, and texture. This article is authored by the leading experts in these areas. The subjects are discussed individually and recommendations for further study are listed in the final section.

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Current issues in recrystallization: a review

List of Contributors. 1. The Development of Automated Diffraction in Scanning and Transmission Electron Microscopy D.J. Dingley. 2. Theoretical Framework for Electron Backscatter Diffraction V. Randle. 3. Representation of Texture in Orientation Space K. Rajan. 4. Rodriques-Frank Representations of Crystallographic Texture K. Rajan. 5. Fundamentals of Automated EBSD S.I. Wright. 6. Studies on the Accuracy of Electron Backscatter Diffraction Measurements M.C. Demirel, B.S. El-Dasher, B.L. Adams, A.D. Rollett. 7. Phase Identification Using Electron Backscatter Diffraction in the Scanning Electron Microscope J.R. Michael. 8. Three-Dimensional Orientation Imaging D.J. Jensen. 9. Automated Electron Backscatter Diffraction: Present State and Prospects R.A. Schwarzer. 10. EBSD: Buying a Systems A. Eades. 11. Hardware and Software Optimization for Orientation Mapping and Phase Identification P.P. Camus. 12. An Automated EBSD Acquisition and Processing System P. Rolland, K.G. Dicks. 13. Advanced Software Capabilities for Automated EBSD S.I. Wright, D.P. Field, D.J. Dingley. 14. Strategies for Analysis of EBSD Datasets W.E. King, J.S. Stolken, M. Kumar, A.J. Schwartz. 15. Structure-Property Relations: EBSD-Based Materials-Sensitive Design B.L. Adams, B.L. Henrie, L.L. Howell, R.J. Balling. 16. Use of EBSD Data in Mesoscale Numerical Analyses R. Becker, H. Weiland. 17. Characterization of Deformed Microstructures D.P. Field, H. Weiland. 18. Anisotropic Plasticity Modeling Incorporating EBSD Characterization of Tantalum and Zirconium J.F. Bingert, G.C. Kaschner, T.A. Mason, P.J. Maudlin, G.T. Gray III. 19. Measuring Strains Using Electron Backscatter Diffraction A.J. Wilkinson. 20. Mapping Residual Plastic Strain in Materials Using Electron Backscatter Diffraction E.M. Lehockey, Yang-Pi Lin, O.E. Lepik. 21.EBSD Contra TEM Characterization of a Deformed Aluminum Single Crystal Xiaoxu Huang, D.J. Jensen. 22. Continuous Recrystallization and Grain Boundaries in a Superplastic Aluminum Alloy T.R. McNelley. 23. Analysis of Facets and Other Surfaces Using Electron Backscatter Diffraction V. Randle. 24. EBSD of Ceramic Materials J.K. Farrer, J.R. Michael, C.B. Carter. 25. Grain Boundary Character Based Design of Polycrystalline High Temperature Superconducting Wires A. Goyal. Index.

Electron Backscatter Diffraction in Materials Science

We study orientation gradients and geometrically necessary dislocations (GNDs) in two ultrafine grained dual-phase steels with different martensite particle size and volume fraction (24 vol.% and 38 vol.%). The steel with higher martensite fraction has a lower elastic limit, a higher yield strength and a higher tensile strength. These effects are attributed to the higher second phase fraction and the inhomogeneous transformation strain accommodation in ferrite. The latter assumption is analyzed using high-resolution electron backscatter diffraction (EBSD). We quantify orientation gradients, pattern quality and GND density variations at ferrite–ferrite and ferrite–martensite interfaces. Using 3D EBSD, additional information is obtained about the effect of grain volume and of martensite distribution on strain accommodation. Two methods are demonstrated to calculate the GND density from the EBSD data based on the kernel average misorientation measure and on the dislocation density tensor, respectively. The overall GND density is shown to increase with increasing total martensite fraction, decreasing grain volume, and increasing martensite fraction in the vicinity of ferrite.

Orientation gradients and geometrically necessary dislocations in ultrafine grained dual-phase steels studied by 2D and 3D EBSD

A new microscopy, called orientation imaging microscopy, is described. Imaging results from precise measurements of local lattice orientation facilitated by backscattered Kikuchi diffraction. The hardware configuration of the microscope is described, and a formal description of image formation is developed. Application of the method to several cubic materials and material conditions is described. Emphasis is given to those areas of application where new insight into polycrystalline microstructures has begun to emerge.

Orientation imaging: The emergence of a new microscopy

Nickel-based IN738LC samples were built by selective laser melting (SLM). To evaluate the anisotropic mechanical behavior of IN738LC material due to layer-wise build up, specimens were built with their cylinder axis (loading direction) oriented either parallel to the building direction, or perpendicular to the building direction and at 45° to the laser scanning direction. After building up the specimens by SLM, they were investigated either under the ‘as-built’ condition or after heat treatment and compared to IN738LC cast material. The analysis of microstructural anisotropy in SLM made IN738LC specimens was done by using EBSD, EDX and X-ray texture analysis methods, and then correlated with anisotropic material behavior observed during tensile and creep testing at room temperature and 850 °C. All SLM samples possess the same general texture, with the majority of grains forming one single component of a cube texture with one of the cubic axes parallel to the building direction, and another cubic axis parallel to the laser scanning direction. The Young׳s modulus determined during tensile testing is significantly lower parallel to the building direction than perpendicular to the building direction, with the values for cast IN738LC material in between. Creep behavior of specimens with loading parallel to the building direction is superior compared to specimens with loading axis normal to the building direction. The anisotropy of Young׳s modulus was modeled based on the single crystal elastic tensor and the measured crystallographic preferred orientations, and compares well with the data from tensile tests.

Texture, anisotropy in microstructure and mechanical properties of IN738LC alloy processed by selective laser melting (SLM)

High-pressure and high-temperature torsion experiments on olivine aggregates in dislocation creep show about 15 to 20% strain weakening before steady-state behavior, characterized by subgrain-rotation recrystallization and a strong lattice preferred orientation. Such weakening may provide a way to focus flow in the upper mantle without a change in deformation mechanism. Flow laws derived from low strain data may not be appropriate for use in modeling high strain regions. In such areas, seismic wave propagation will be anisotropic with an axis of approximate rotational symmetry about the shear direction. In contrast to current thinking, the anisotropy will not indicate the orientation of the shear plane in highly strained, recrystallized olivine-rich rocks.

https://science.sciencemag.org/content/sci/290/5496/1564.full.pdf

High Shear Strain of Olivine Aggregates: Rheological and Seismic Consequences

https://eps.mcgill.ca/~courses/c644/Willy's%20reading%20(2005)/Willy%20-%20Landtwing%20et%20al.%20(2005).pdf

Copper deposition during quartz dissolution by cooling magmatic–hydrothermal fluids: The Bingham porphyry

Understanding the nature of complex zeolite particles, used as catalysts in industrial reactors, is vital for their further development. Now, an integrated approach to visualizing granules of a hierarchical MFI-type zeolite, on length scales from nanometres to millimetres, is reported.

https://www.researchgate.net/profile/Karsten_Kunze/publication/237089443_Visualization_of_hierarchically_structured_zeolite_bodies_from_macro_to_nano_length_scales/links/0f31753b260e433f99000000.pdf

Karsten Kunze

Papers

Orientation imaging: The emergence of a new microscopy

Texture, anisotropy in microstructure and mechanical properties of IN738LC alloy processed by selective laser melting (SLM)

High Shear Strain of Olivine Aggregates: Rheological and Seismic Consequences

Copper deposition during quartz dissolution by cooling magmatic–hydrothermal fluids: The Bingham porphyry

Visualization of hierarchically structured zeolite bodies from macro to nano length scales