Download or read book Micromechanical study on the deformation behaviour of directionally solidified NiAl Cr eutectic composites written by Kumar, Amritesh and published by KIT Scientific Publishing. This book was released on 2017-11-06 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure evolution in tribological interfaces studied by multilayer model alloys written by Cihan, Ebru and published by KIT Scientific Publishing. This book was released on 2020-10-21 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent studies of deformation mechanisms of metals and alloys pioneer the better investigation of the friction and wear behavior of materials with well-defined initial microstructures. Within this scope, in this work, the effect of sub-surface deformations on the resulting friction and wear behavior has been searched by means of a systematic experimental study on Au-Ni metallic multilayer model alloy system.

Download or read book On the Electro Chemo Mechanical Coupling in Solid State Batteries and its Impact on Morphological Interface Stability written by Ganser, Markus and published by KIT Scientific Publishing. This book was released on 2021-03-09 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid state batteries with a lithium metal electrode are considered the next generation of high energy battery technology. Unfortunately, lithium metal is prone to harmful protrusion or dendrite growth which causes dangerous cell failure. Within this work the problem of protrusion growth is tackled by deriving a novel electro-chemo-mechanical theory tailored for binary solid state batteries which is then used to discuss the impact of mechanics on interface stability by numerical studies.

Download or read book The Impact of Recycling on the Fibre and the Composite Properties of Carbon Fibre Reinforced Plastics written by Hüther, Jonas Johannes and published by KIT Scientific Publishing. This book was released on 2020-06-19 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phase field Modeling of Phase Changes and Mechanical Stresses in Electrode Particles of Secondary Batteries written by Zhang, Tao and published by KIT Scientific Publishing. This book was released on 2021-09-27 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most storage materials exhibit phase changes, which cause stresses and, thus, lead to damage of the electrode particles. In this work, a phase-field model for the cathode material NaxFePO4 of Na-ion batteries is studied to understand phase changes and stress evolution. Furthermore, we study the particle size and SOC dependent miscibility gap of the nanoscale insertion materials. Finally, we introduce the nonlocal species concentration theory, and show how the nonlocality influences the results.

Download or read book Characterisation and Modelling of Continuous Discontinuous Sheet Moulding Compound Composites for Structural Applications written by Trauth, Anna and published by KIT Scientific Publishing. This book was released on 2020-12-11 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this work is to significantly deepen the understanding of the material and the structural behaviour of continuous-discontinuous SMC composites, following a holistic approach to investigate microscopic aspects, macroscopic mechanical behaviour as well as failure evolution at the coupon, structure and component level. In addition, criteria to evaluate the effect of hybridisation are introduced and modelling approaches are presented and discussed.

Download or read book Consequences of hydroxyl generation by the silica water reaction Part I Diffusion and Swelling written by Fett, Theo and published by KIT Scientific Publishing. This book was released on 2022-07-11 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water diffusing into silica surfaces gives rise for several effectson diffusion behaviour and mechanical properties. Water added to silica glass increases its specific volume so that the silica expands near the surface. Mechanical boundary conditions give rise for compressive “swelling stresses”. This fact provides a tool for the interpretation of many experimental observations from literature.

Download or read book Development of NbN based Kinetic Inductance Detectors on sapphire and diamond substrates for fusion plasma polarimetric diagnostics written by Mazzocchi, Francesco and published by KIT Scientific Publishing. This book was released on 2022-07-01 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work aimed at designing, studying and producing the first prototypes of KIDs tailored for fusion plasma polarimetric diagnostics. Diamond was considered for the first time as substrate material for low-temperature superconducting detectors given its unmatched optical, radiation hardness and thermal qualities, properties necessary for working environments potentially saturated with radiation. This work represents a first step toward the optimization and final application of this technology.

Download or read book Modeling transport properties and electrochemical performance of hierarchically structured lithium ion battery cathodes using resistor networks and mathematical half cell models written by Birkholz, Oleg and published by KIT Scientific Publishing. This book was released on 2022-10-05 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hierarchically structured active materials in electrodes of lithium-ion cells are promising candidates for increasing gravimetric energy density and improving rate capability of the system. To investigate the influence of cathode structures on the performance of the whole cell, efficient tools for calculating effective transport properties of granular systems are developed and their influence on the electrochemical performance is investigated in specially adapted cell models.

Download or read book Consequences of hydroxyl generation by the silica water reaction Part II Global and local Swelling Part III Damage and Young s Modulus written by Fett, Theo and published by KIT Scientific Publishing. This book was released on 2022-07-11 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water diffusing into silica surfaces gives rise for several effects on diffusion behaviour and mechanical properties. In a preceding booklet, we focused on diffusion and fiber strengths and deformations which were obtained by water soaking under external loading. In the present booklet we deal with results and interpretations of strength increase in the absence of applied stresses.

Download or read book Dynamic Model based Analysis of Oxygen Reduction Reaction in Gas Diffusion Electrodes written by Röhe, Maximilian and published by KIT Scientific Publishing. This book was released on 2024-01-09 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the first simulation model of oxygen depolarized cathodes (ODC), which are silver catalyst-based gas diffusion electrodes, is presented that considers the phase equilibrium of the gas-liquid interface and structure-related inhomogeneities in electrolyte distribution. By means of the model it has been identified that mass transport of water and ions in the liquid phase is a crucial factor for electrode performance and how it is influenced by the electrode structure.

Download or read book Multiscale Modeling of Curing and Crack Propagation in Fiber Reinforced Thermosets written by Schöller, Lukas and published by KIT Scientific Publishing. This book was released on 2024-03-15 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the production of fiber-reinforced thermosets, the resin material undergoes a reaction that can lead to damage. A two-stage polymerization reaction is modeled using molecular dynamics and evaluations of the system including a fiber surface are performed. In addition, a phase-field model for crack propagation in heterogeneous systems is derived. This model is able to predict crack growth where established models fail. Finally, the model is used to predict crack formation during curing.

Download or read book Characterization of Dislocation Structures and Deformation Mechanisms in As grown and Deformed Directionally Solidified NiAl Mo Composites written by and published by . This book was released on 2015 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, directionally solidified (DS) NiAl-Mo eutectic composites were strained to plastic strain values ranging from 0% to 12% to investigate the origin of the previously observed stochastic versus deterministic mechanical behaviors of Mo-alloy micropillars in terms of the development of dislocation structures at different pre-strain levels. The DS composites consist of long, [1 0 0] single-crystal Mo-alloy fibers with approximately square cross-sections embedded in a [1 0 0] single-crystal NiAl matrix. Scanning transmission electron microscopy (STEM) and computational stress state analysis were conducted for the current study. STEM of the as-grown samples (without pre-straining) reveal no dislocations in the investigated Mo-alloy fibers. In the NiAl matrix, on the other hand, a(1 0 0)-type dislocations exist in two orthogonal orientations: along the [1 0 0] Mo fiber axis, and wrapped around the fiber axis. They presumably form to accommodate the different thermal contractions of the two phases during cool down after eutectic solidification. At intermediate pre-strain levels (4-8%), a/2(1 1 1)-type dislocations are present in the Mo-alloy fibers and the pre-existing dislocations in the NiAl matrix seem to be swept toward the interphase boundary. Some of the dislocations in the Mo-alloy fibers appear to be transformed from a(1 0 0)-type dislocations present in the NiAl matrix. Subsequently, the transformed dislocations in the fibers propagate through the NiAl matrix as a(1 1 1) dislocations and aid in initiating additional slip bands in adjacent fibers. Thereafter, co-deformation presumably occurs by (1 1 1) slip in both phases. With a further increase in the pre-strain level (>10%), multiple a/2(1 1 1)-type dislocations are observed in many locations in the Mo-alloy fibers. Interactions between these systems upon subsequent deformation could lead to stable junctions and persistent dislocation sources. Finally, the transition from stochastic to deterministic, bulk-like behavior in sub-micron Mo-alloy pillars may therefore be related to an increasing number of multiple a(1 1 1) dislocation systems within the Mo fibers with increasing pre-strain, considering that the bulk-like behavior is governed by the forest hardening of these junctions.

Download or read book Characterization of Dislocation Structures and Deformation Mechanisms in As grown and Deformed Directionally Solidified NiAl u2013 Mo Composites written by and published by . This book was released on 2015 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, directionally solidified (DS) NiAl–Mo eutectic composites were strained to plastic strain values ranging from 0% to 12% to investigate the origin of the previously observed stochastic versus deterministic mechanical behaviors of Mo-alloy micropillars in terms of the development of dislocation structures at different pre-strain levels. The DS composites consist of long, [1 0 0] single-crystal Mo-alloy fibers with approximately square cross-sections embedded in a [1 0 0] single-crystal NiAl matrix. Scanning transmission electron microscopy (STEM) and computational stress state analysis were conducted for the current study. STEM of the as-grown samples (without pre-straining) reveal no dislocations in the investigated Mo-alloy fibers. In the NiAl matrix, on the other hand, a(1 0 0)-type dislocations exist in two orthogonal orientations: along the [1 0 0] Mo fiber axis, and wrapped around the fiber axis. They presumably form to accommodate the different thermal contractions of the two phases during cool down after eutectic solidification. At intermediate pre-strain levels (4–8%), a/2(1 1 1)-type dislocations are present in the Mo-alloy fibers and the pre-existing dislocations in the NiAl matrix seem to be swept toward the interphase boundary. Some of the dislocations in the Mo-alloy fibers appear to be transformed from a(1 0 0)-type dislocations present in the NiAl matrix. Subsequently, the transformed dislocations in the fibers propagate through the NiAl matrix as a(1 1 1) dislocations and aid in initiating additional slip bands in adjacent fibers. Thereafter, co-deformation presumably occurs by (1 1 1) slip in both phases. With a further increase in the pre-strain level (>10%), multiple a/2(1 1 1)-type dislocations are observed in many locations in the Mo-alloy fibers. Interactions between these systems upon subsequent deformation could lead to stable junctions and persistent dislocation sources. Finally, the transition from stochastic to deterministic, bulk-like behavior in sub-micron Mo-alloy pillars may therefore be related to an increasing number of multiple a(1 1 1) dislocation systems within the Mo fibers with increasing pre-strain, considering that the bulk-like behavior is governed by the forest hardening of these junctions.

Download or read book Directional Solidification Microstructures and Mechanical Properties of Cr Cr3Si Eutectic Alloys written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Alloys based on intermetallics have been considered for high temperature structural applications. However, many of these alloys suffer from intrinsic brittleness and low fracture toughness at ambient temperature. Therefore, ductile-phase-toughened intermetallic composites are being investigated as a means to improve the fracture toughness. A subset of this class of materials is in-situ composites produced by directional solidification of intermetallic eutectics. In this study, the Cr-Cr3Si eutectic system is selected as a model system to investigate composites by directional solidification, where the strong, but brittle Cr3Si is combined with a more ductile Cr-rich solid solution. A series of binary Cr-Si alloys with silicon concentrations ranging from 13 to 24 at.% were produced by arc melting and drop casting. These compositions span the composition (15 at.% Si) at which a eutectic reaction is reported in the phase diagram. The microstructure of the Cr-16.05 at.% Si alloy is fully lamellar and devoid of any proeutectic phases suggesting that the best composition for obtaining a fully lamellar structure is Cr-16.05 at.% Si rather than the eutectic composition (Cr-15 at.% Si) indicated in the phase diagram. The eutectic microstructure consists of alternating lamellae of Cr (solid solution) and Cr3Si (intermetallic). Uniform and well-aligned lamellar structures were obtained over a fairly wide range of solidification conditions, but not at very low or very high growth rates where degenerate and cellular structures, respectively, were obtained. The lamellar spacing was found to increase with decreasing solidification rate, in agreement with the Jackson-Hunt theory. In addition, for a fixed growth rate, the lamellar spacing was found to increase with increasing rotation rate. The growth directions in the lamellar eutectic were found to be 100 for the Cr3Si phase and 111 for the Cr solid solution phase. Eutectic microstructures (rod or lamellar) could also be produced at off-eutectic compositions, but only for a limited range of growth conditions. The mechanical properties of the individual lamellae and the Cr-Cr3Si composites were examined by nanoindentation, Vicker's hardness testing and three-point bend testing. It was found that the Vicker's hardness of Cr-Cr3Si composites is about HV847, independent of the lamellar spacing. The Young's modulus of the Cr-Cr3Si eutectic composites measured by ultrasonic techniques is 312 GPa, which is in reasonably good agreement with the nanoindentation results (within 5%). The fracture toughness of single crystals of Cr3Si is very low (2.6 MPa[square root]m).

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1997 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metals Abstracts Index written by and published by . This book was released on 1995 with total page 1388 pages. Available in PDF, EPUB and Kindle. Book excerpt: