TY - JOUR A1 - Brückner, Udo A1 - Link, T. A1 - Epishin, A. T1 - Moiré fringes for misfit measurements at incoherent y/y'-interfaces of nickel-base superalloys PY - 1998 U6 - https://doi.org/10.1016/S1359-6462(98)00337-6 SN - 0956-716X VL - 39 IS - 10 SP - 1463 EP - 1469 PB - Pergamon Press CY - Elmsford, NY AN - OPUS4-942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Link, T. A1 - Österle, Werner T1 - Röntgenmikroanalyse im Elektronenmikroskop, Teil IV: Superlegierungen PY - 1991 SN - 0032-678X VL - 28 SP - 101 EP - 114 PB - Hanser CY - München AN - OPUS4-2469 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Epishin, Alexander A1 - Link, T. A1 - Brückner, Udo T1 - Microstructural stability of CMSX-4 and CMSX-10 under high temperature creep conditions T2 - 8th Liège Conference "Materials for Advanced Power Engineering 2006" CY - Liege, Belgien DA - 2006-01-01 KW - Superalloys KW - CMSX-4 KW - Creep KW - Microstructure KW - CMSX-10 PY - 2006 SN - 3-89336-436-6 N1 - Serientitel: Schriften des Forschungszentrums Jülich - Reihe Energietechnik / Energy Technology – Series title: Schriften des Forschungszentrums Jülich - Reihe Energietechnik / Energy Technology IS - 53 SP - 507 EP - 520 PB - Forschungszentrum Jülich CY - Jülich AN - OPUS4-13702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Link, T. A1 - Epishin, Alexander A1 - Klaus, M. A1 - Brückner, Udo A1 - Reznicek, A. T1 - (100) Dislocations in nickel-base superalloys: Formation and role in creep deformation N2 - α(1 0 0) Dislocations are observed in nickel-base superalloys after creep deformation at high temperatures and low stresses. They are formed in the γ/γ´ interfaces by a three step mechanism. First, primary dislocations with Burgers vector α/2(1 0 1) and 60° character are left behind in the interfaces when dislocation loops glide through the γ channels. The 60° dislocations move into edge orientation and react forming secondary dislocations α/2(1 1 0). In the third step, new primary dislocations are knit into the already existing meshes of primary and secondary dislocations, which results in hexagonal misfit dislocation networks consisting of secondary dislocations α/2(1 1 0) and tertiary dislocations α(1 0 0), both of edge type. This self-organisation process is explained by dislocation theory and crystallography. Creep deformation accelerates when the α(1 0 0) interfacial dislocations enter the γ´ phase. During their climb towards the opposite interface, they attain a characteristic rectangular shape. This shape and the importance of the α(1 0 0) super dislocations for creep deformation are discussed. KW - Superalloys KW - Creep KW - Dislocation reactions KW - Dislocation theory KW - Deformation mechanisms PY - 2005 SN - 0921-5093 SN - 1873-4936 VL - 405 IS - 1-2 SP - 254 EP - 265 PB - Elsevier CY - Amsterdam AN - OPUS4-11968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, Alexander A1 - Link, T. A1 - Brückner, Udo A1 - Fedelich, Bernard T1 - Residual Stresses in the Dendritic Structure of Single-Crystal Nickel-Based Superalloys PY - 2005 SN - 0031-918x SN - 1531-8672 VL - 100 IS - 2 SP - 192 EP - 199 PB - MAIK Nauka/Interperiodica Publ. CY - Moscow AN - OPUS4-11969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, Alexander A1 - Link, T. T1 - Mechanisms of high-temperature creep of nickel-based superalloys under low applied stresses KW - Superalloys KW - Creep PY - 2004 SN - 1478-6435 SN - 0031-8086 VL - 84 IS - 19 SP - 1979 EP - 2000 PB - Taylor & Francis CY - London AN - OPUS4-7144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Epishin, Alexander A1 - Brückner, Udo A1 - Link, T. A1 - Portella, Pedro Dolabella ED - Dias, A. T1 - Investigation of stresses in superalloys by analysis of y/y'-Microstructure T2 - 6th European Conference on Residual Stresses CY - Coimbra, Portugal DA - 2002-07-10 KW - Superalloys KW - Stress KW - Misfit KW - Rafting PY - 2002 SN - 0-87849-900-8 SN - 0255-5476 N1 - Serientitel: Materials science forum – Series title: Materials science forum IS - 404/407 SP - 287 EP - 292 PB - Trans Tech Publ. CY - Uetikon-Zuerich AN - OPUS4-7147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Epishin, Alexander A1 - Link, T. ED - Green, K. T1 - Mechanisms of high temperature creep of nickel-base superalloys under low applied stress T2 - Superalloys 2004 / 10th International Symposium on Superalloys 2004 CY - Seven Springs, PA, USA DA - 2004-09-19 KW - Superalloys KW - Creep KW - Porosity KW - Dislocations KW - Diffusion PY - 2004 SN - 0-87339-576-X SP - 137 EP - 143 PB - TMS CY - Warrendale AN - OPUS4-7149 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, Alexander A1 - Link, T. A1 - Portella, Pedro Dolabella A1 - Brückner, Udo T1 - Evolution of the gamma/gamma'-microstructure during high-temperature creep of a nickel-base superalloy KW - Nickel alloys KW - Creep KW - Mesostructure KW - Scanning electron microscopy (SEM) KW - Image analysis PY - 2000 SN - 1359-6454 SN - 1873-2453 VL - 48 SP - 4169 EP - 4177 PB - Elsevier Science CY - Kidlington AN - OPUS4-7152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Alymov, M. I. A1 - Epishin, Alexander A1 - Nolze, Gert A1 - Link, T. A1 - Bedov, S. A1 - Ankudinov, A. B. T1 - Electron microscopy investigation of the structure of a compact extruded from nanopowder of nickel KW - EBSD KW - SAED KW - TEM KW - SEM KW - Extrusion KW - Nano-technology PY - 2007 SN - 1816-5230 VL - 2 IS - 3-4 SP - 124 EP - 129 PB - Akademperiodyka CY - Kyïv AN - OPUS4-14845 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, Alexander A1 - Link, T. A1 - Nolze, Gert T1 - SEM investigation of interfacial dislocations in nickel-base superalloys N2 - A new technique for investigation of interfacial dislocations in nickel-base superalloys by scanning electron microscopy is presented. At high temperatures the pressure of interfacial dislocations against the γ/γ'-interface causes grooves. This 'fingerprint of the dislocation network' is visualized by deep selective etching, which removes the γ'-phase down to the γ/γ'-interface. Compared with transmission electron microscopy, the proposed method has important advantages: observation of large sample areas, no superposition of dislocations lying in different specimen depths, possibility of three-dimensional view of dislocation configurations, information about the dislocation mobility, reduced time for preparation and visualization. The method can be applied for multiphase materials where the interface is grooved by interfacial dislocations. KW - Dislocation structure KW - Interfaces KW - Nickel alloys KW - Scanning electron microscopy PY - 2007 SN - 0022-2720 SN - 1365-2818 VL - 228 IS - 2 SP - 110 EP - 117 PB - Blackwell CY - London AN - OPUS4-16039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Link, T. A1 - Epishin, Alexander A1 - Thibault, X. A1 - Haibel, A. T1 - High resolution synchrotron topography of Nickelbase superalloys T2 - 69. DPG Physikertagung CY - Berlin, Germany DA - 2006-03-07 PY - 2006 AN - OPUS4-12176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Link, T. A1 - Epishin, Alexander A1 - Thibault, X. A1 - Haibel, A. T1 - High resolution synchrotron topography of Nickelbase superalloys T2 - European Congress on Advanced Materials and Processes, EUROMAT 2005 CY - Prague, Czech Republic DA - 2005-09-05 PY - 2005 AN - OPUS4-12177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Fedelich, Bernard A1 - Link, T. A1 - Feldmann, Titus A1 - Svetlov, I.L. T1 - Pore annihilation in a single-crystal nickel-base superalloy during hot isostatic pressing: Experiment and modelling N2 - Pore annihilation during hot isostatic pressing (HIP) was investigated in the single-crystal nickel-base superalloy CMSX-4 experimentally by interrupted HIP tests at 1288 °C/103 MPa. The kinetics of pore annihilation was determined by density measurement and quantitative metallography. Transmission electron microscopy of a HIPed specimen showed that the pores shrink via dislocation movement on octahedral glide planes. Theoretically pore closure under HIP condition was modelled by the finite element method using crystal plasticity and large strain theories. The modelling gives a similar kinetics of pore annihilation as observed experimentally, however somewhat higher annihilation rate. KW - Nickel based superalloys KW - Electron microscopy KW - Crystal plasticity KW - Bulk deformation KW - Finite element method PY - 2013 U6 - https://doi.org/10.1016/j.msea.2013.08.034 SN - 0921-5093 SN - 1873-4936 VL - 586 SP - 342 EP - 349 PB - Elsevier CY - Amsterdam AN - OPUS4-29418 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epishin, A.I. A1 - Link, T. A1 - Fedelich, Bernard A1 - Svetlov, I.L. A1 - Golubovskiy, E.R. T1 - Hot isostatic pressing of single-crystal nickel-base superalloys: mechanism of pore closure and effect on mechanical properties N2 - Pore annihilation was investigated in the single-crystal nickel-base superalloy CMSX-4. HIP tests at 1288 °C/103 MPa were interrupted at different times, then the specimens were investigated by TEM, metallography and density measurements. The kinetics of pore annihilation was determined. The pore closure mechanism was identified as plastic deformation on the octahedral slip systems. A model describing the kinetics of pore closure has been developed on the base of crystal plasticity and large strain theory. Mechanical tests with the superalloy CMSX-4 and the Ru-containing superalloy VGM4 showed, that HIP significantly increases the fatigue life at low temperatures but has no effect on creep strength. T2 - Eurosuperalloys 2014 - 2nd European symposium on superalloys and their applications CY - Giens, France DA - 12.05.2014 PY - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-316410 N1 - Serientitel: MATEC Web of conferences – Series title: MATEC Web of conferences VL - 14 SP - 08003-1 EP - 08003-6 PB - EDP Sciences AN - OPUS4-31641 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klingelhöffer, Hellmuth A1 - Epishin, Alexander A1 - Link, T. T1 - Low cycle fatigue of the single-crystal nickel-base superalloy CMSX-4 - Anistropy and effect of creep damage KW - Single crystal nickel-base superalloys KW - CMSX-4 KW - Creep KW - Low cycle fatigue PY - 2009 SN - 0025-5300 VL - 51 IS - 5 SP - 291 EP - 294 PB - Hanser CY - München AN - OPUS4-19430 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Brückner, Udo A1 - Link, T. A1 - Fedelich, Bernard T1 - X-ray reflections from the Gamma/Gamma'-microstructure of nickel-base superalloys: effect of the plane tilting N2 - The shape of X-ray reflections from the cuboidal γ/γ'-microstructure was investigated. The measurements were performed on the 4th generation single-crystal nickel-base superalloy TMS138. It is shown that reflections from non-cubic crystallographic planes split not only in d-scale due to the different spacing of the γ- and γ'-lattices but also in the pole figure due to the tilting of γ-lattice planes. This tilting results from the elastic distortion of the γ-lattice caused by the γ/γ'-misfit. The results obtained are discussed under the methodical aspect of misfit measurement. KW - Nickel-base alloys KW - X-ray diffraction KW - Lattice distortion PY - 2010 U6 - https://doi.org/10.3139/146.110315 SN - 1862-5282 VL - 101 IS - 5 SP - 589 EP - 593 PB - Carl Hanser CY - München AN - OPUS4-21512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Link, T. A1 - Epishin, A. A1 - Fedelich, Bernard T1 - Inhomogeneity of misfit stresses in nickel-base superalloys: Effect on propagation of matrix dislocatiion loops N2 - It is shown experimentally that, during annealing and creep under low applied stresses, matrix dislocation loops frequently cross-glide. The periodic length of the zigzag dislocations deposited in the interfaces is equal to that of the γ/γ'-microstructure. Initially, the zigzag dislocations move in the (001) interface by a combination of glide and climb but then they stop near the γ'-edges and align along (100). Reactions of such dislocations lead to the formation of square interfacial networks consisting of (100) oriented edge dislocations. The complex dislocation movement is explained by the inhomogeneity of the misfit stresses between γ- and γ'-lattices. The tensile components of the stress tensor drive the dislocations through the channel, whereas the shear components near the γ'-edges cause the zigzag movement and the (100) alignment. The total effect is the most efficient relaxation of the misfit stresses. The results are relevant, especially for single-crystal superalloys of the newest generations, which have an increased γ/γ'-misfit due to the high level of refractory elements. KW - Superalloy KW - Creep KW - Dislocation KW - Misfit stress PY - 2009 U6 - https://doi.org/10.1080/14786430902877810 SN - 1478-6435 SN - 0031-8086 VL - 89 IS - 13 SP - 1141 EP - 1159 PB - Taylor & Francis CY - London AN - OPUS4-19522 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Link, T. A1 - Svetlov, I. L. A1 - Nolze, Gert A1 - Saliwan Neumann, Romeo A1 - Lucas, H. T1 - Mechanism of porosity growth during homogenisation in single crystal nickel-based superalloys N2 - Several mechanisms for porosity growth in single crystal nickel-based superalloys during homogenisation heat treatment have been proposed in the literature. They were carefully checked using different experimental methods, namely quantitative light microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and density measurements. It is shown that the main mechanism is the Kirkendall–Frenkel effect, i.e. generation of voids due to uncompensated efflux of Al atoms from dissolving γ/γ′-eutectic areas. The Al diffusion is supported by the afflux of vacancies from surrounding γ-matrix which results in porosity growth. This conclusion is confirmed by the estimation of the vacancy afflux towards the dissolving eutectic. KW - Ni-base superalloy KW - Eutectic KW - Vacancies KW - Porosity PY - 2013 VL - 104 IS - 8 SP - 776 EP - 782 PB - Carl Hanser Verlag AN - OPUS4-37983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. I. A1 - Link, T. A1 - Nolze, Gert A1 - Svetlov, I. L. A1 - Bokshtein, B. S. A1 - Rodin, A. O. A1 - Saliwan Neumann, Romeo A1 - Oder, Gabriele T1 - Diffusion processes in multicomponent nickel-base superalloy-nickel system N2 - Optical and scanning electron microscopy, as well as electron microprobe analysis and electron backscatter diffraction, have been used to study diffusion processes that occur in a diffusion pair that consistsof a single-crystal CMSX-10 nickel-base superalloy and polycrystalline nickel, at temperatures of 1050–1250°C. It has been found that, in this system, the distributions of γ-stabilizing elements (Cr, Co, W, and Re) are described by the Boltzmann solution for diffusion between two semiinfinite plates of a binary alloy. The processing of these distributions has shown that the diffusion coefficients of Cr, Co, W, and Re in the multicomponent system are close to those in binary alloys of these elements with Ni. The diffusion redistribution of the elements leads to the dissolution of the γ′ phase in the nickel-base superalloy, growth of nickel grains toward the superalloy constituent of the diffusion pair, and the formation of porosity on both sides of the migrating interface, which is determined from a crystal misorientation of the alloy single crystal and nickel grains. KW - Ni-base superalloy KW - Interface KW - Diffusion KW - Phase transformation KW - Porosity PY - 2014 SN - 0031-918X VL - 115 IS - 1 SP - 21 EP - 29 AN - OPUS4-37980 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. I. A1 - Petrushin, N. V. A1 - Link, T. A1 - Nolze, Gert A1 - Loshchinin, Yu. V. A1 - Gerstein, G. T1 - Thermal stability of the structure of a heat-resistant cobalt alloy hardened with intermetallic γ'-phase precipitates N2 - The thermal stability of the microstructure of a heat-resistant cobalt alloy, which consists of a γ solid solution strengthened with γ'-phase precipitates, has been studied. The temperature behavior of the dissolution of the hardening γ' phase and the kinetics of its coarsening at 700 and 800°C have been determined. It is found that, during prolonged annealing at 800°C, the γ' → β phase transformation occurs. KW - Superalloy KW - Microstructure KW - Hardening KW - Electron backscatter diffraction KW - TEM PY - 2016 U6 - https://doi.org/10.1134/S0036029516040078 SN - 0036-0295 VL - 2016 IS - 4 SP - 286 EP - 291 PB - Pleiades Publishing AN - OPUS4-37768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Link, T. A1 - Nolze, Gert T1 - SEM investigation of interfacial dislocations in nickel-base superalloys N2 - A new technique for investigation of interfacial dislocations in nickel-base superalloys by scanning electron microscopy is presented. At high temperatures the pressure of interfacial dislocations against the gamma/gamma'-interface causes grooves. This 'fingerprint of the dislocation network' is visualized by deep selective etching, which removes the gamma'-phase down to the gamma/gamma'-interface. Compared with transmission electron microscopy, the proposed method has important advantages: observation of large sample areas, no superposition of dislocations lying in different specimen depths, possibility of three-dimensional view of dislocation configurations, information about the dislocation mobility, reduced time for preparation and visualization. The method can be applied for multiphase materials where the interface is grooved by interfacial dislocations. KW - Dislocation structure KW - Interface KW - Nickel alloys KW - SEM PY - 2007 VL - 228 IS - 2 SP - 110 EP - 117 PB - The Royal Microscopical Society AN - OPUS4-38016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Petrushin, N. A1 - Hvatzkiy, K. A1 - Gerasimov, V. A1 - Link, T. A1 - Epishin, A. A1 - Nolze, Gert A1 - Gerstein, G. T1 - A single-crystal co-base superalloy strengthened by gamma' precipitates: structure and mechanical properties N2 - An experimental Co-base superalloy was designed from the Ni-base system by exchange of Ni and Co concentrations. The alloy consist of a Co-matrix (γ phase) strengthened by cuboidal precipitates Co3(Al,X) (γ' phase). The γ'-solvus temperature is 1?005?°C. [001] single crystals of this alloy were solidified and tested for tension at different temperatures up to 1?000?°C. It was found that the Co-base alloy has a much lower yield stress than a corresponding Ni-base alloy, but a much higher ductility. The partitioning behaviour of the alloying elements in the Co-base alloy and the deformation mechanisms were investigated by scanning and transmission electron microscopy. KW - Microstructure KW - Precipitation KW - Stress PY - 2015 U6 - https://doi.org/10.1002/adem.201500088 SN - 1438-1656 VL - 17 IS - 6 SP - 755 EP - 760 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-34474 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Midtlyng, Jan A1 - Epishin, A. I. A1 - Petrushin, N. V. A1 - Link, T. A1 - Nolze, Gert A1 - Svetlov, I. L. A1 - Reimers, W. T1 - Creep behavior of a γ΄-strengthened Co-base alloy with zero γ/γ΄-lattice misfit at 800 °C, 196 MPa N2 - Deformation and structural behavior of an experimental γ΄-strengthened Co-base alloy during creep at 800 °C and 196 MPa have been investigated. The characteristic features of this alloy are zero γ/γ΄-lattice misfit and a fine γ/γ΄-microstructure. In the initial condition, the γ΄-precipitates in this alloy are small (size of about 100 nm), have polyhedral morphology, and are separated by the very narrow c-channels (width of about 10 nm). The tests performed up to about 1% creep strain (about 500 h creep time) gave creep curves with a slow constant strain rate and without an apparent transient creep, typical for superalloys with nonzero misfit. In this initial stage of creep, entering of the narrow γ-channels by dislocations is blocked by a strong Orowan force. The micromechanism of creep was identified as an octahedral glide of h011i superdislocations simultaneously in two phases, γ and γ΄. The γ/γ΄-microstructure with zero misfit shows no rafting but rapidly coarsens isotropically. It is concluded that zero misfit is beneficial at the initial stages of the creep but is unfavourable for longterm creep because of the continuous microstructural coarsening. KW - Co-Basis-Legierung KW - Gitterfehlpassung KW - Kriechen KW - Ausscheidung PY - 2017 U6 - https://doi.org/10.1557/jmr.2017.424 SN - 0884-2914 SN - 2044-5326 VL - 32 IS - 24 SP - 4466 EP - 4474 PB - Cambridge Univ. Press CY - Cambridge AN - OPUS4-44027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chyrkin, A. A1 - Epishin, A. A1 - Pillai, R. A1 - Link, T. A1 - Nolze, Gert A1 - Quaddaker, W. J. T1 - Modeling interdiffusion processes in CMSX-10/Ni diffusion couple N2 - A diffusion couple between directionally solidified nickel and the single crystal Ni-base superalloy CMSX-10 was produced by hot pressing in vacuum. The diffusion couples were heat treated at temperatures between 1050 and 1250 °C. The exposed samples were characterized by SEM/EBSD/EPMA. The interdiffusion results in dissolution of the c¢-Ni3 Al in the superalloy and in growth of nickel grains towards CMSX-10. Rapid diffusion of aluminum from the superalloy into pure nickel leads to a significant formation of pores in the superalloy. The interdiffusion processes were modelled using the finite-element simulation software DICTRA with the databases TCNi5 and MobNi2, tailored specially for Ni-base superalloys. The effect of alloying elements on the interdiffusion profiles is discussed in terms of alloy thermodynamics. The calculated element concentration profiles are in good agreement with the EPMA measurements. The interdiffusion modeling correctly predicts the shapes of the concentration profiles, e.g. kinks on the Al and Ti profiles in the vicinity of the original interface in the joint. The calculation predicts with reasonable accuracy the extent and the location of the Kirkendall porosity. KW - Chemical potential KW - Diffusion KW - EBSD KW - Composition profiles KW - DICTRA modeling KW - Electron probe microanalysis KW - EPMA PY - 2016 U6 - https://doi.org/10.1007/s11669-015-0444-9 SN - 1547-7037 VL - 37 IS - 2 SP - 201 EP - 211 PB - Springer AN - OPUS4-35776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epishin, A.I. A1 - Link, T. A1 - Nolze, Gert A1 - Fedelich, Bernard A1 - Schriever, Sina T1 - Creep behaviour of the single-crystal nickel-base superalloy CMSX-4 at ultra-high homologous temperature N2 - Data about the creep behaviour of metals and their alloys at temperatures close to the melting point are very limited. The reason is that most engineering alloys are used at temperatures below 0.6-0.8 of their melting point, so, Investigation of creep at higher temperatures has no practical relevance. For some special applications however it is important, in our case hot isostatic pressing (HIP) of single-crystal turbine blades cast from nickel-base superalloys. In order to remove porosity the blades are HlPed at temperatures between y'-solvus and solidus where superalloy has no strengthening y'-phase and therefore is very soft. For example, the Company Howmet Castings HIPs the superalloy CMSX-4 at the temperature 1288aC, which corresponds to a homologous temperature of about 0.97=1561 K/1612 K (solidus temperature). Therefore knowledge about the creep behaviour of CMSX-4 at this temperature and understanding of the creep mechanisms are necessary to model the kinetics of pore closure during HIP as well as to plan the Parameters of the HIP process. T2 - CREEP 2015 - 13th International conference on creep and fracture of engineering materials and structures CY - Toulouse, France DA - 31.5.2015 PY - 2015 VL - 825 SP - 19 EP - 20 AN - OPUS4-33527 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Epishin, Alexander A1 - Link, T. A1 - Brückner, Udo A1 - Klingelhöffer, Hellmuth A1 - Portella, Pedro Dolabella T1 - The effect of high temperature creep damage on low cycle fatigue of CMSX-4 T2 - 8th Liège Conference "Materials for Advanced Power Engineering 2006" CY - Liege, Belgium DA - 2006-01-01 KW - Superalloys KW - CMSX-4 KW - Single crystal KW - Creep KW - Fatigue PY - 2006 SN - 3-89336-436-6 N1 - Serientitel: Schriften des Forschungszentrums Jülich - Reihe Energietechnik / Energy Technology – Series title: Schriften des Forschungszentrums Jülich - Reihe Energietechnik / Energy Technology IS - 53 SP - 317 EP - 325 PB - Forschungszentrum Jülich CY - Jülich AN - OPUS4-13701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Epishin, Alexander A1 - Link, T. A1 - Brückner, Udo A1 - Fedelich, Bernard A1 - Portella, Pedro Dolabella ED - Green, K. T1 - Effects of segregation in nickel-base superalloys: dendritic stresses T2 - Superalloys 2004 / 10th International Symposium on Superalloys 2004 CY - Seven Springs, PA, USA DA - 2004-09-19 KW - Nickel-base superalloys KW - Dendritic structure KW - Segregation KW - Residual stresses PY - 2004 SN - 0-87339-576-X SP - 537 EP - 543 PB - TMS CY - Warrendale AN - OPUS4-7150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, Alexander A1 - Brückner, Udo A1 - Portella, Pedro Dolabella A1 - Link, T. T1 - Influence of small rhenium additions on the lattice spacing of nickel solid solution N2 - The influence of small rhenium additions on the lattice spacing of a nickel solid solution was investigated using a nickel–rhenium single crystal with an axial macrosegregation of rhenium. The effect of rhenium on the lattice spacing of the nickel solid solution was found to be similar to that of tungsten. KW - Nickel alloys KW - Crystallography PY - 2003 U6 - https://doi.org/10.1016/S1359-6462(02)00436-0 SN - 1359-6462 SN - 1872-8456 VL - 48 IS - 4 SP - 455 EP - 459 PB - Elsevier CY - Oxford AN - OPUS4-2278 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Brückner, Udo A1 - Epishin, Alexander A1 - Link, T. A1 - Portella, Pedro Dolabella ED - Böttger, A. T1 - Creep induced evolution of internal stresses and structure in a single crystal nickel-base superalloy N2 - Changes in the structure of single-crystal (SC) superalloy SRR99 during creep at 980 °C and 200 MPa were investigated. Geometrical parameters of the y/y'-microstructure, y/y'-misfit, stresses in the phases and local misorientation of the structure were determined at defined points of the dendritic structure by use of X-ray diffraction (XRD), wavelength dispersive X-ray spectroscopy (WDXS), scanning (SEM) and transmission (TEM) electron microscopy. Correlation of the microstructural period and local misorientation of the structure with creep strain were found. T2 - 5th European Conference on Residual Stresses CY - Delft-Noordwijkerhout, the Netherlands DA - 1999-10-28 KW - Creep KW - Dendrite KW - Misfit KW - Segregation KW - Superalloys PY - 2000 UR - http://cat.inist.fr/?aModele=afficheN&cpsidt=1381837 SN - 0-87849-855-9 SN - 0255-5476 N1 - Serientitel: Materials science forum – Series title: Materials science forum IS - 347/349 SP - 363 EP - 367 PB - Trans Tech Publ. CY - Uetikon-Zürich AN - OPUS4-7151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Brückner, Udo A1 - Epishin, Alexander A1 - Link, T. A1 - Fedelich, Bernard A1 - Portella, Pedro Dolabella ED - Denis, S. T1 - Dendritic stresses in Nickel-base superalloys T2 - 7th International Conference on Residual Stresses CY - Xi'an, China DA - 2004-06-14 KW - Single crystal KW - Superalloy KW - Dendritic structure KW - Residual stresses KW - X-ray diffraction KW - Nickelbasis-Superlegierung KW - Dendritisches Gefüge KW - Röntgenbeugung PY - 2005 SN - 0-87849-969-5 SN - 0255-5476 N1 - Serientitel: Materials science forum – Series title: Materials science forum IS - 490/491 SP - 497 EP - 502 PB - Trans Tech Publ. CY - Uetikon-Zürich AN - OPUS4-7148 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, Alexander A1 - Link, T. A1 - Klingelhöffer, Hellmuth A1 - Fedelich, Bernard A1 - Portella, Pedro Dolabella T1 - Creep damage of single-crystal nickel base superalloys: mechanisms and effect on low cycle fatigue N2 - The main mechanisms of creep damage of single-crystal nickel-base superalloys are the loss of the interface coherency, coarsening of the γ / γ'-microstructure, precipitation of topologically closed packed phases and growth of porosity. This degradation deteriorates the mechanical properties such as yield stress, creep lifetime and especially low-cycle fatigue life, which can be reduced nearly by a factor of 10. The degradation kinetics during creep was characterised quantitatively on the superalloy CMSX-4. A new non-destructive testing technique was applied to cover a wide test parameter range with few specimens in a relatively short time: repeated load annealing of wedge shaped specimens. KW - Creep damage KW - Nickel-base superalloys KW - Low-cycle fatigue KW - Rafting KW - Porosity KW - Prior exposure PY - 2010 U6 - https://doi.org/10.3184/096034009X12603595726283 SN - 0960-3409 VL - 27 IS - 1 SP - 53 EP - 59 PB - Science Reviews CY - St. Albans, Herts. [u.a.] AN - OPUS4-23912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard A1 - Epishin, A. A1 - Link, T. A1 - Klingelhöffer, Hellmuth A1 - Künecke, Georgia A1 - Portella, Pedro Dolabella ED - Huron, E.S. ED - Reed, R.C. ED - Hardy, M.C. ED - Mills, M.J. ED - Montero, R.E. ED - Portella, Pedro Dolabella ED - Telesman, J. T1 - Rafting during high temperature deformation in a single crystal superalloy: experiments and modeling T2 - Superalloys 2012 - 12th International symposium on superalloys CY - Seven, Springs, PA, USA DA - 2012-09-09 KW - Creep KW - Single crystal KW - Rafting KW - Modeling KW - CMSX-4 KW - Low-cycle-fatigue PY - 2012 SP - 491 EP - 500 PB - Wiley AN - OPUS4-26842 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard A1 - Epishin, A. A1 - Link, T. A1 - Klingelhöffer, Hellmuth A1 - Portella, Pedro Dolabella A1 - Skrotzki, Birgit ED - Maruyama, K. ED - Abe, F. ED - Igarashi, M. ED - Kishida, K. ED - Suzuki, M. ED - Yoshimi, K. T1 - Implementation of creep induced rafting into mechanical modelling of superalloys T2 - 12th International conference on creep and fracture of engineering materials and structures CY - Kyoto, Japan DA - 2012-05-27 KW - Single-crystal nickel-base superalloys KW - Microstructural degradation KW - Creep KW - Modelling KW - Rafting PY - 2012 SP - 1 EP - 4(?) AN - OPUS4-27564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fedelich, Bernard A1 - Epishin, A. A1 - Link, T. A1 - Klingelhöffer, Hellmuth A1 - Künecke, Georgia A1 - Portella, Pedro Dolabella T1 - Experimental characterization and mechanical modeling of creep induced rafting in superalloys N2 - A constitutive model has been developed for the high temperature mechanical behavior of single crystal superalloys, including rafting and its consequences. The flow stress depends on the γ channel width via the Orowan stress. An evolution equation for channel widening during high temperature straining has been derived and calibrated with measurements. Therein, rafting is assumed to be driven by the relaxation of internal stresses. The model is able to represent the mechanical softening at high stresses consecutive to rafting. The model has been applied to simulate rafting during uniaxial creep in several crystal orientations, in notched specimens as well as in cyclically loaded specimens. KW - Single crystal KW - Superalloys KW - Rafting KW - Creep KW - Viscoplasticity KW - Constitutive law PY - 2012 U6 - https://doi.org/10.1016/j.commatsci.2012.05.071 SN - 0927-0256 VL - 64 SP - 2 EP - 6 PB - Elsevier CY - Amsterdam AN - OPUS4-26401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Link, T. A1 - Klingelhöffer, Hellmuth A1 - Fedelich, Bernard A1 - Brückner, Udo A1 - Portella, Pedro Dolabella T1 - New technique for characterization of microstructural degradation under creep: Application to the nickel-base superalloy CMSX-4 N2 - A new experimental technique (repeated load annealing of flat wedge shaped specimens) was proposed for characterization of microstructural degradation under creep conditions. This technique was applied to investigate the microstructural degradation of the nickel-base superalloy CMSX-4 in a wide range of temperatures and stress levels. The results obtained allowed to describe analytically the kinetics of rafting, which is important to predict the reduction of fatigue lifetime and yield stress. KW - Microstructural degradation KW - Nickel-base superalloys KW - Rafting PY - 2009 U6 - https://doi.org/10.1016/j.msea.2008.04.135 SN - 0921-5093 SN - 1873-4936 VL - 510-511 SP - 262 EP - 265 PB - Elsevier CY - Amsterdam AN - OPUS4-19354 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Epishin, Alexander A1 - Link, T. A1 - Klingelhöffer, Hellmuth A1 - Fedelich, Bernard A1 - Portella, Pedro Dolabella ED - S.R. Holdsworth, ED - I.A. Shibli, T1 - Creep damage mechanisms of single-crystal Nickel base superalloys T2 - 2nd ECCC Creep Conference CY - Zurich, Switzerland DA - 2009-04-21 KW - Creep damage KW - Nickel-base superalloys PY - 2009 SN - 978-1-60595-005-1 SP - 692 EP - 701 PB - DEStech Publications, Inc. AN - OPUS4-19448 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fedelich, Bernard A1 - Künecke, Georgia A1 - Epishin, A. A1 - Link, T. A1 - Portella, Pedro Dolabella T1 - Constitutive modelling of creep degradation due to rafting in single-crystalline Ni-base superalloys N2 - A constitutive model for the mechanical behaviour of single-crystalline superalloys at high temperatures has been developed. The model relies on the slip system theory and is able to predict rafting and its influence on plastic flow. The kinetics of rafting are assumed to be driven by the reduction of the internal stresses represented by the macroscopic back-stress. The rafting effect is incorporated in the model through the dependence of the Orowan stress on the channel width. The model has been validated for the alloy CMSX-4 at 950 °C. The rafting part of the model has been calibrated by measurements of the channel widths after several levels of creep strains and for several loads. KW - Single crystal superalloy KW - Creep KW - Rafting KW - Constitutive modelling KW - Viscoplasticity PY - 2009 U6 - https://doi.org/10.1016/j.msea.2008.04.089 SN - 0921-5093 SN - 1873-4936 VL - 510-511 SP - 273 EP - 277 PB - Elsevier CY - Amsterdam AN - OPUS4-19353 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Klingelhöffer, Hellmuth A1 - Epishin, A. A1 - Link, T. A1 - Portella, Pedro Dolabella ED - Portella, Pedro Dolabella ED - T. Beck, ED - M. Okazaki, T1 - Low cycle fatigue of the single crystal nickel-base superalloy CMSX-4: anisotropy and effect of creep damage T2 - 6th International Conference on Low Cycle Fatigue (LCF 6) CY - Berlin, Germany DA - 2008-09-08 KW - Anisotropy of mechanical properties KW - Effect of creep damage on LCF KW - Single-crystal nickel-base superalloys PY - 2008 SP - 403 EP - 408 AN - OPUS4-17914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -