Download or read book Characterization of a Nickel base Superalloy Through Electrical Resistivity microstructure Relationships Facilitated by Small Angle Scattering written by Ricky Lee Whelchel and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel-base superalloys obtain high temperature mechanical properties through formation of precipitate phases formed via heat treatment. The precipitate microstructure evolves with heat treatment or thermal exposure, which can lead to degrading mechanical properties. This project focuses on the use of electrical resistivity as a non-destructive testing method to monitor the precipitate phase in Waspaloy (a polycrystalline nickel-base superalloy). The evolution of the precipitate microstructure is characterized throughout the volume of the specimens using both small angle neutron scattering (SANS) and ultra small angle X-ray scattering (USAXS) measurements. These measurements are also aided by microscopy and X-ray diffraction measurements.

Download or read book Resistivity Microstructure Relationships in Nickel Base Superalloys Used in Gas Turbine Engines for Power Generation and as Interconnects in Solid Oxide Fuel Cells written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the results accomplished during this 3-year with funds from this grant. The most important new contribution was the development of a microstructural model, based on analysis of the small angle scattering spectra that can relate the measured electrical resistivity to the precipitate population present in a nickel base superalloy in a quantitative way. A total of 24 research articles were published or were in press at the time the final report was written.

Download or read book Alloy Design and Characterization of Strengthened Nickel based Superalloys for Additive Manufacturing written by Jinghao Xu and published by Linköping University Electronic Press. This book was released on 2021-01-28 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel-based superalloys, an alloy system bases on nickel as the matrix element with the addition of up to 10 more alloying elements including chromium, aluminum, cobalt, tungsten, molybdenum, titanium, and so on. Through the development and improvement of nickel-based superalloys in the past century, they are well proved to show excellent performance at the elevated service temperature. Owing to the combination of extraordinary high-temperature mechanical properties, such as monotonic and cyclic deformation resistance, fatigue crack propagation resistance; and high-temperature chemical properties, such as corrosion and oxidation resistance, phase stability, nickel-based superalloys are widely used in the critical hot-section components in aerospace and energy generation industries. The success of nickel-based superalloy systems attributes to both the well-tailored microstructures with the assistance of carefully doped alloying elements, and the intently developed manufacturing processes. The microstructure of the modern nickel-based superalloys consists of a two-phase configuration: the intermetallic precipitates (Ni,Co)3(Al,Ti,Ta) known as γ′ phase dispersed into the austenite γ matrix, which is firstly introduced in the 1940s. The recently developed additive manufacturing (AM) techniques, acting as the disruptive manufacturing process, offers a new avenue for producing the nickel-based superalloy components with complicated geometries. However, γ′ strengthened nickel-based superalloys always suffer from the micro-cracking during the AM process, which is barely eliminated by the process optimization. On this basis, the new compositions of γ′ strengthened nickel-based superalloy adapted to the AM process are of great interest and significance. This study sought to design novel γ′ strengthened nickel-based superalloys readily for AM process with limited cracking susceptibility, based on the understanding of the cracking mechanisms. A two-parameter model is developed to predict the additive manufacturability for any given composition of a nickel-based superalloy. One materials index is derived from the comparison of the deformation-resistant capacity between dendritic and interdendritic regions, while another index is derived from the difference of heat resistant capacity of these two spaces. By plotting the additive manufacturability diagram, the superalloys family can be categorized into the easy-to-weld, fairly-weldable, and non-weldable regime with the good agreement of the existed knowledge. To design a novel superalloy, a Cr-Co-Mo-W-Al-Ti-Ta-Nb-Fe-Ni alloy family is proposed containing 921,600 composition recipes in total. Through the examination of additive manufacturability, undesired phase formation propensity, and the precipitation fraction, one composition of superalloy, MAD542, out of the 921,600 candidates is selected. Validation of additive manufacturability of MAD542 is carried out by laser powder bed fusion (LPBF). By optimizing the LPBF process parameters, the crack-free MAD542 part is achieved. In addition, the MAD542 superalloy shows great resistance to the post-processing treatment-induced cracking. During the post-processing treatment, extensive annealing twins are promoted to achieve the recrystallization microstructure, ensuring the rapid reduction of stored energy. After ageing treatment, up to 60-65% volume fraction of γ′ precipitates are developed, indicating the huge potential of γ′ formation. Examined by the high-temperature slow strain rate tensile and constant loading creep testing, the MAD542 superalloy shows superior strength than the LPBF processed and hot isostatic pressed plus heat-treated IN738LC superalloy. While the low ductility of MAD542 is existed, which is expected to be improved by modifying the post-processing treatment scenarios and by the adjusting building direction in the following stages of the Ph.D. research. MAD542 superalloy so far shows both good additive manufacturability and mechanical potentials. Additionally, the results in this study will contribute to a novel paradigm for alloy design and encourage more γ′-strengthened nickel-based superalloys tailored for AM processes in the future.

Download or read book Nickel Base Single Crystals Across Length Scales written by Loeïz Nazé and published by Elsevier. This book was released on 2021-09-28 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel Base Single Crystals Across Length Scales is addresses the most advanced knowledge in metallurgy and computational mechanics and how they are applied to superalloys used as bare materials or with a thermal barrier coating system. Joining both aspects, the book helps readers understand the mechanisms driving properties and their evolution from fundamental to application level. These guidelines are helpful for students and researchers who wish to understand issues and solutions, optimize materials, and model them in a cross-check analysis, from the atomistic to component scale. The book is useful for students and engineers as it explores processing, characterization and design. - Provides an up-to-date overview on the field of superalloys - Covers the relationship between microstructural evolution and mechanical behavior at high temperatures - Discusses both basic and advanced modeling and characterization techniques - Includes case studies that illustrate the application of techniques presented in the book

Download or read book Material Characterization of Nickel based Super Alloys Through Ultrasonic Inspection written by Pranaam Haldipur and published by . This book was released on 2006 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel-based super alloys are widely used in aircraft engine components, mainly in turbine disks and the high-pressure compressor. Extensive data on the mechanical properties of these alloys is available. However, fundamental data relating micro-structural features to ultrasonic properties, in turn controlling the inspectability, are not available. Knowledge of these relationships would facilitate improvements in current Ni billet inspections. A single scattering model has been found to be very effective in simulating the effects of backscattered noise on the ultrasonic inspection of billets and forgings engine alloy materials. The work on this dissertation is focused on evaluating the effectiveness of the single scattering model in predicting backscattered noise in the nickel-based alloys. Attenuation, grain size and single-crystal elastic constants are important input parameters that need to be evaluated for making the predictions of noise levels. Determination of these quantities on a number of nickel-based super alloy samples is reported and studied how noise levels predicted with the current single scattering model compare with the direct measurements of noise on the same samples. In Chapter 1, experimental investigations of the relationships between ultrasonic properties (velocity, attenuation, and backscattered grain noise FOM) and the microstructure are reported. A close relationship was established between the measured attenuation and the Noise FOM, a result consistent with classical theories for backscattering and attenuation but inconsistent to observations in titanium. Chapter 2 describes a quantitative study of the relationship of the experimental observations reported in Chapter 1 to the predictions of classical theories, which require as input the single-crystal elastic constants of the grains and the grain size. The single-crystal elastic constants for these alloys are unknowns and an effort to infer the same for the nickel-based super alloys from ultrasonic measurements is reported. In Chapter 3, a detailed study of the accuracy of the single scattering model to predict the grain noise generated by the microstructure was carried out. Detailed measurements and model calculations were carried out to quantify the breakdown of the single scattering model the comparison of theory and experiment provided strong evidence for the presence of multiple scattering effects.

Download or read book Characterization of Microstructure Evolution of Nickel Base Superalloys in Support of the Development of a Grain Growth Model written by Daniel Richard Corwin and published by . This book was released on 2007 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: I would like to thank Dr. Michael Mills, my adviser, for providing excellent support and guidance throughout this work. I'd also like to thank Eric Payton for his contributions and advice regarding practically all aspects of this project. Close collaboration with Dr. Yunzhi Wang, Gang Wang, and Ning Ma has been a very beneficial experience that has given me a valuable understanding of microstructure modeling. I am also very appreciative of the help received from Peter Sarosi, Libor Kovarik, and Ray Unocic regarding the transmission electron microscopy performed in this research. I wish to thank Dave Mourer, Deb Whitis, and Dan Wei at GE Aviation for providing guidance and direction in addition to making this research opportunity possible. Thanks to Ron Tolbert for helping procure the needed materials. I am grateful for the superior quality of the Campus Electron Optics Facility at OSU, and I'd like to specifically thank Cameron Begg and Henk Colijn for their assistance with SEM and TEM operation. This research was funded by GE Aviation.

Download or read book Characterization and Modeling of Microstructure Development in Nickel base Superalloy Welds written by and published by . This book was released on 1999 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modelling and Characterisation of the Microstructure in a Polycrystalline Nickel base Superalloy written by David Matthew Collins and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructure Property Relationships in Directionally Solidified Single Crystal Nickel Base Superalloys written by RA. MacKay and published by . This book was released on 1988 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses some of the microstructural features which influence the creep properties of directionally solidified and single-crystal nickel-base superalloys. Gamma prime precipitate size and morphology, ?-?' lattice mismatch, phase instability, alloy composition, and processing variations are among the factors considered. Recent experimental results are reviewed and related to the operative deformation mechanisms and to the corresponding mechanical properties. Special emphasis is placed on the creep behavior of single-crystal superalloys at high temperatures, where directional ?' coarsening is prominent, and at lower temperatures, where ?' coarsening rates are significantly reduced. It can be seen that very subtle changes in microstructural features can have profound effects on the subsequent properties of these materials.

Download or read book On the Path dependent Microstructure Evolution of an Advanced Powder Metallurgy Nickel base Superalloy During Heat Treatment written by Nicholas J. Krutz and published by . This book was released on 2020 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: The realization of advanced alloy compositions in service relies on a thorough understanding of metallurgical processing variables. Within this work, the gamma prime precipitation of an advanced powder metallurgy nickel-base superalloy during controlled cooling from supersolvus temperatures is compared to prior alloy generations using a complement of characterization and modeling approaches. The on-cooling precipitation of the alloy is studied and characterized to calibrate a multi-scale precipitation model. The proposed framework incorporates a computationally efficient addition to the mean-field modeling approach that increases its ability to model dynamic, multi-modal gamma prime burst events. The gamma prime size predicted by the model shows good agreement with experimental results. The precipitation calculation is applied to the element integration points of a continuum Finite Element heat conduction simulation, where the latent heat generated from the precipitation is accounted for. The results are compared to experimental findings and indicate potential use of the model for evaluating precipitation effects at multiple length scales. The lattice misfit evolution of two commercial PM nickel superalloys during cooling from supersolvus temperatures is also characterized, using in-situ synchrotron X-Ray Diffraction (XRD). The diffraction pattern deconvolution necessary for quantifying misfit was accomplished by combining observation of the superlattice peak intensities with thermodynamic modeling to quantify the intensity relationship between the overlapping phases. The misfit from the XRD measurements was compared to the Scanning Electron Microscopy observations of gamma prime particle shapes for a subset of the experimental conditions. The trend of measured misfit agreed with the microstructural characterization. Time-resolved observations of the on-cooling lattice parameter suggest that lower-temperature changes to the peak intensity characteristics coincide with low misfit magnitudes and a plausible connection to gamma prime burst events. Variation in cooling rate for this alloy and its predecessors shows a tendency for unstable precipitate growth with slower rates. To better understand the effect of precipitate morphology on defect interaction, a series of lab heat treatments of varied cooling rates were carried out and the mechanical response characterized. A phase-field based approach is used to simulate the growth instability of gamma prime precipitates during cooling and compared to post-mortem characterization using serial sectioning and reconstruction. Phase-field modeling is then used to interrogate the interaction of the particle morphology with planar dislocation evolution. It was determined that the incipient stages of particle evolution are dictated by interface growth instability more so than elastic anisotropy effects. Planar deformation in the presence of more evolved particles tended to promote Orowan looping while smaller particles with smaller gamma channel widths showed a tendency for stacking fault formation under the conditions characterized. To further understand precipitate morphology on properties, a stand-alone spectral-based microelasticity model is employed to predict the stress field around the particles. First order deformation assumptions are assessed to understand the effect of the microelastic stress field interacting with dislocations. By comparing the fields of varied precipitate morphologies, it is observed that the magnitudes and spatial distribution of the stress tensor components vary by morphology and may contribute to differences from a defect interaction standpoint.

Download or read book Ni Based Superalloys written by James Coakley and published by Trans Tech Publications Ltd. This book was released on 2020-07-28 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aggregated Book

Download or read book Advanced Microcharacterization of Nickel base Superalloys written by and published by . This book was released on 2000 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this project was to characterize the microstructural and microchemical effects of a process revision on HAYNES{reg{underscore}sign} 242{trademark}, a polycrystalline Ni-base superalloy used principally for high temperature applications, such as seal and containment rings in gas turbine engines. The process revision from the current one-step heat treating cycle to a two-step heat treatment would result in savings of energy and ultimately cost to the consumer. However, the proposed process revision could give rise to unforeseen microstructural modifications, such as a change in the size distribution of the ordered particles responsible for alloy strength or the formation of additional phases, which could affect alloy properties and hence performance. Advanced microcharacterization methods that allow images of the microstructure to be acquired at length scales from one micrometer down to the atomic level were used to reveal the effect of the process revision on alloy microstructure. Energy filtered imaging was used to characterize the size distribution and morphology of ordered precipitates and other phases, as well as the partitioning behavior of major elements (Ni, Mo, Cr) among these phases. The compositions of individual ordered particles, including fine-scale compositional variations at precipitate-matrix interfaces, and solute segregation behavior at grain boundaries were characterized at the atomic level by atom probe tomography. The atomic site distributions of selected elements in the ordered precipitates were characterized by atom-location by channeling-enhanced microanalysis (ALCHEMI). The results of these advanced microcharacterization methods were correlated with mechanical testing of similar alloys to address structure-property relationships.

Download or read book The Microstructure of Superalloys written by Madeleine Durand-Charre and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Presents all the main aspects of the microstructure of nickel-base superalloys, and includes micrographs chosen from among a large range of commercial and academic alloys, from the as-cast product to in-situ components, worn from in-service use. Including more than 100 illustrations, the text explains all the transformation mechanisms involved in the origination (creation) of microstructures during solidification or heat treatments (crystallization paths, segregation, crystal orientation, precipitation, TCP, coarsening and rafting, etc.). It includes up-to-date information and data such as phase diagrams, crystallographic structures, and relationships with functional properties. Nearly 300 references provide a key to further investigation."--Provided by publisher.

Download or read book Microstructure and Mechanical Properties of Nickel based Superalloy Hastelloy X Fabricated by Laser Powder Bed Fusion written by Oscar Sanchez Mata and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Additive manufacturing (AM), particularly laser powder bed fusion (LPBF) has been used to process Ni-based superalloys as an alternative to traditional manufacturing methods. However, they can be prone to cracking when fabricated through LPBF. Hastelloy X (HX) is a solid solution strengthened (SSS) alloy that although being categorized as readily weldable, suffers from cracking during LPBF. This document presents a study of crack-free LPBF HX microstructures, their behaviour after post-processing and their relationship with mechanical properties. Moreover, the application of unique microstructural features that result from LPBF processing to scale from bulk to more complex parts and tailor mechanical properties is documented. Crack-free HX fabricated through LPBF from powder having a standard chemical composition is reported. Electron backscatter diffraction (EBSD) analysis evidenced columnar grains parallel to the building direction (BD). The columnar sub-grain solidification microstructure was found to be finer than reported elsewhere. Mo-enriched carbides (~50 nm), were identified along interdendritic regions. The crack-free condition was maintained after heat treatment at 1177 °C for 1 h and its microstructure was analyzed. Dense and crack-free specimens were printed in both horizontal and vertical orientations. Samples were analyzed in as-built (AB), hot isostatic pressing treatment (HIP), and conventional heat treatment (HT) conditions. Tensile testing was done at room and elevated temperature (RT, ET = 750°C). AB samples showed columnar grains and a partial fiber texture aligned with the BD, which was reduced after HIP and HT. Mo and Cr carbides were found at RT which grew after ET. AB samples displayed high ultimate tensile strength (UTS) up to 924 ± 10 MPa, while strength values remained close to a reference HX wrought alloy after HIP and HT. Although lower ductility was observed for AB samples at ET, elongation was improved after HIP and HT. Strength and elongation comparable to that of the wrought alloy at RT can be obtained by only performing conventional HT, without the need of HIP. Dense and crack-free LPBF HX thin cylindrical struts with diameters from 0.25 to 2 mm were built. Their crystallographic texture transitioned from a 110 || BD fiber texture (2 mm), to a single crystal 110 || BD (0.25 mm). The size of cellular sub-grain microstructure increased as strut diameter decreased and was linked with an inverse trend in microhardness, which was the highest in the 2 mm strut due to a smaller cell size. Lower hardness in regions close to the strut edges was also related to a larger observed cell size. From tensile testing, elongation was measured at 35-50%. Deformation twinning and lattice rotation after testing were observed. Differences in strength between struts of different diameter were discussed. Fractography analysis confirmed the ductile fracture behavior. Finally, the unique strong crystallographic texture behaviour of LPBF HX was studied in more detail. Tensile properties at RT were investigated along the 100, 110, and 111 crystallographic orientations. Tensile behavior was highly dependent on crystallographic orientation and showed a good combination of strength and ductility when compared with other LPBF HX. EBSD analysis after fracture revealed deformation twinning in 110 and 111 samples, but not in 100. Crystallographic orientation had an impact on the effective stacking fault energies and on the critical stress for deformation twinning. The latter was near or below the yield strength (YS) value for 110 and 111, while it was above the UTS of the 100 orientation. The YS value of 111 (807 ± 28 MPa) was higher than for 100 (693 ± 8 MPa) and 110 (648 ± 13 MPa). Results suggest that deformation twinning can occur in SSS Ni-based superalloys at RT. In contrast to the 100 and 111 orientations, rotation of the lattice after deformation was found for the 110 direction"--

Download or read book Characterization and Deformation Behavior of Microstructural Gradients in the Low Solvus High Refractory LSHR Nickel Base Superalloy written by Samuel Joshua Morris Kuhr and published by . This book was released on 2016 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructure and the Characterisation of Mechanical Properties of Wire Arc Additively Manufactured Nickel base Superalloys written by Cui Seow and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Non destructive Electrical Characterization of Controlled Waspaloy Microstructures written by V. Siva Kumar G. Kelekanjeri and published by . This book was released on 2007 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research, controlled Waspaloy microstructures are produced with the objective of studying microstructural evolution in this alloy via non-destructive electrical measurements. Waspaloy is a precipitation-hardenable gamma-gamma' nickel-base superalloy that is used in turbine blade applications demanding superior strength retention capabilities at elevated temperatures. Overall, three different sets of microstructures were produced that varied systematically as a function of the matrix (gamma) grain size and gamma' precipitate size distribution or just the latter. Initial solutionizing treatments conducted at 1045°C, 1090°C and 1145°C resulted in average y grain size of 13, 52 and 89 mum respectively. A vacancy stabilization treatment at 1045°C followed the solutionizing treatments in Set I experiments, after which the specimens were aged at 800°C for durations ranging from 0.1 hrs to 100 hrs. In Sets 11 and III, the matrix grain size was kept unchanged by an initial solution-treatment at 1145°C. The stabilization treatment at 1045°C was only conducted in Set II after the solution-treatment. Aging experiments were then conducted at 700°C (or 725°C in Set III), 800°C and 875°C to study the growth kinetics of gamma' precipitate distribution. The specimens with controlled microstructures were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD), ultra small-angle x-ray scattering (USAXS) and dc four-point probe resistivity. The applicability of two and four-probe ac impedance techniques was also investigated.