Carolin Körner

Friedrich-Alexander-University Erlangen-Nürnberg | FAU · Department of Materials Science and Engineering

This study explores the potential of periodic open cellular structures (POCS) that combine the auxetic and the shape memory effect (SME) with the aim of enhancing heat transfer in catalytic tubular reactors. On the one hand, these structures exhibit a negative Poisson's ratio, contracting perpendicular to the load axis under compression, driven by...

Electron beam powder bed fusion is an advanced additive manufacturing technology that utilizes an electron beam to fabricate complex metallic components layer by layer. It is well known, that the beam profile is one of the most important key ingredients for successful processing. Surprisingly, the beam profile during the process is almost unknown u...

The fabrication of complex geometries with uniform material properties in electron beam powder bed fusion (PBF-EB) remains a major challenge. Local material properties in PBF-EB are determined by the local thermal conditions and the spatio-temporal melt pool evolution. The local thermal conditions are governed by the cumulative heating effect on th...

Cover Picture of Effect of Scanning Strategies on Grain Structure and Texture of Additively Manufactured Lattice Struts: A Numerical Exploration (https://doi.org/10.1002/adem.202400661)

Electron beam powder bed fusion (PBF-EB) is an additive manufacturing technique that fabricates customized components using an electron beam in a controlled vacuum environment. Maintaining high vacuum quality is crucial to prevent feedstock contamination. However, the inherent nature of the PBF-EB process introduces a gas load into the system, pote...

Electron beam powder bed fusion (PBF‐EB) is a promising technology for fabricating complex parts with near‐net‐shape precision. Moreover, PBF‐EB offers a unique opportunity to tailor the microstructure, thereby tuning local mechanical properties. Numerical simulation has emerged as a powerful tool for predicting the evolution of texture and grain s...

Computational superalloy development is a powerful alternative to the conventional experimental approach. Based on thermodynamic databases and the CALPHAD method, it is possible to estimate the properties of a large number of potential alloys and select the most promising ones. However, the accuracy of the databases and complementary property model...

Preheating is an essential process step in electron beam powder bed fusion. It has the purpose of establishing a sintered powder bed and maintaining an elevated temperature. The sintered powder bed reduces the risk of smoke and in combination with the elevated temperature improves the processability. Today, the line-ordering preheating scheme is wi...

Electron beam–powder bed fusion (PBF-EB) is an additive manufacturing process that utilizes an electron beam as the heat source to enable material fusion. However, the use of a charge-carrying heat source can sometimes result in sudden powder explosions, usually referred to as “Smoke”, which can lead to process instability or termination. This expe...

Electron optical imaging is the most promising process monitoring method in electron beam powder bed fusion. State of the art in modern machines is the installation of a single detector in the top center of the build chamber. Exemplary applications are the reconstruction of digital twins of manufactured parts to compare their dimensional accuracy o...

One impeding factor for faster solidification in typical investment casting processes is the limited heat removal capability. This study compares the classical Bridgman technique and the fluidized carbon bed cooling (FCBC) casting method. In particular, the influence of the thermal design is investigated in terms of microstructural and compositiona...

Electron beam powder bed fusion (PBF-EB) is an additive manufacturing process that utilizes an electron beam as the heat source to enable material fusion. However, the use of a charge carrying heat source can sometimes result in sudden powder explosions, usually referred to as "Smoke", which can lead to process instability or termination. This expe...

This study explores the impact of energy input and build orientation on the anisotropic mechanical and functional properties of Ti-rich Nitinol (NiTi) produced via electron beam powder bed fusion (PBF-EB), integrated with layerwise in-situ monitoring of the melted surface via backscatter electron detection (ELO). NiTi, a binary alloy of nickel and...

Cemented carbides containing titanium carbide (TiC), characterized by low specific weight, superior hardness, and excellent high‐temperature resistance, are widely used as wear‐resistant cutting tools and brake discs. Instead of using conventional powder metallurgical approaches, composites comprising TiC and stainless steel are fabricated in this...

To enhance the mechanical properties of NiAl–(Cr,Mo) in situ composites for high‐temperature structural use, achieving a regular eutectic microstructure is crucial. A novel alloy with a composition of Ni30.6Al36Cr31.4Mo2 is developed that exhibits a significantly reduced solidification interval compared to well‐studied alloys such as Ni33Al33Cr28Mo...

Solid–liquid phase transitions of metals and alloys play an important role in many technical processes. Therefore, corresponding numerical process simulations need adequate models. The enthalpy method is the current state-of-the-art approach for this task. However, this method has some limitations regarding multicomponent alloys as it does not cons...

The successful application of laser powder bed fusion (PBF-LB/M) for fabricating bulk metallic glass (BMG) parts heavily relies on the development of effective process strategies. An optimal process strategy for BMGs is required to go beyond manufacturing defect-free parts and address the critical aspect of minimizing crystallization. However, trad...

Co‐extrusion of both half‐cells in tubular PEM water electrolyzers can lower the costs for hydrogen production, since the number of components is reduced and the production process is simplified. However, after co‐extrusion of the inner half‐cell and the ion exchange membrane, the membrane is in its fluoride sulfonyl form and must be hydrolyzed to...

The latest advances in additive manufacturing have given rise to an increasing interest in additively built lattice structures due to their superior properties compared to foams and honeycombs. The foundation of these superior properties is a tailored microstructure, which is difficult to achieve in additive manufacturing because of the variety of...

Cost‐ and time‐demanding trial‐and‐error methods have been the historical route for alloy development. A combinatorial approach can significantly simplify and accelerate the development process by characterization of composition dependent properties on material libraries, which are specimens or sets of specimens that map out a certain composition s...

Laminated, powder filled, and dense bulk soft magnets are currently used for various electrical and electronic applications due to their characteristic magnetic properties. In order to systematically investigate the correlation between the structural features and the resulting magnetic performance of various soft magnetic materials, toroidal Fe93.5...

The development of a sample environment for in situ x-ray characterization during metal Electron Beam Powder Bed Fusion (PBF-EB), called MiniMelt, is presented. The design considerations, the features of the equipment, and its implementation at the synchrotron facility PETRA III at Deutsches Elektronen-Synchrotron, Hamburg, Germany, are described....

The dual microstructure concept for γ-TiAl enables the site specific adaption of the material properties to the mechanical load, improving the maximum application temperature of lightweight γ-TiAl turbine blades.

Hot cracking is a major challenge in the additive manufacturing of Ni-base superalloys. Most cracking indicators only consider the alloy composition and its effects on solidification behavior, strength, and ductility. We propose a new model that extends these classical cracking indicators by additionally incorporating the transient thermo-mechanica...

Electron beam powder bed fusion (PBF-EB) is an additive manufacturing (AM) technology that is maturing toward broader industrial applications. However, conventional PBF-EB machines are still limited to 60 kV acceleration voltage (Ub). Therefore, this work presents the first results of a novel prototype PBF-EB machine capable of acceleration voltage...

The dual microstructure concept for gamma titanium aluminides (γ-TiAl) processed via electron beam–powder bed fusion (PBF-EB) provides a huge potential for more efficient jet turbine engines. While the concept is feasible and the mechanical properties are promising, there are still some challenges. For an industrial application, the heat treatment...

The defect-free fabrication of complex geometries with homogeneous properties using line-based hatching strategies remains a major challenge in electron beam powder bed fusion (PBF-EB). Open PBF-EB machines enable the development of new scanning-strategy-based compensation schemes to solve this challenge. This study introduces a new return time com...

Laser powder bed fusion (PBF-LB/M) has been used to fabricate bulk metallic glass (BMG) parts. However, there is still a lack of understanding about the crystallization behavior of BMGs during PBF-LB/M. This article aims to combine experimental and numerical methods to gain a more comprehensive understanding of the BMG crystallization kinetics duri...

The reliable and repeatable fabrication of complex geometries with predetermined homogeneous properties is still a major challenge in electron beam powder bed fusion (PBF-EB). Although previous research identified a variety of process parameter–property relationships, the underlying end-to-end approach, which directly relates process parameters to...

Fe93.5 Si6.5 (wt.%) soft magnetic materials in toroidal shape are additively manufactured by means of Electron Beam Powder Bed Fusion (PBF-EB). Different hatching strategies are applied to realize specific patterns of molten material alternating with non-molten powder particles. The specimens produced using different hatching strategies show identi...

Electron Beam Powder Bed Fusion (PBF-EB) is an Additive Manufacturing (AM) method that utilizes an electron beam to melt and consolidate metal powder. The beam, combined with a backscattered electron detector, enables advanced process monitoring, a method termed Electron Optical Imaging (ELO). ELO is already known to provide great topographical inf...

By increasing the density of interfaces in NiAl–CrMo in situ composites, the mechanical properties can be significantly improved compared to conventionally cast material. The refined microstructure is achieved by manufacturing through electron beam powder bed fusion (PBF‐EB). By varying the process parameters, an equiaxed or columnar cell morpholog...

X-ray-computed tomography (CT) is today’s gold standard for the non-destructive evaluation of internal component defects such as cracks and porosity. Using automated standardized evaluation algorithms, an analysis can be performed without knowledge of the shape, location, or size of the defects. Both the measurement and the evaluation are based on...

In powder bed fusion (PBF) of metals, energy of a laser or electron beam is utilized to form near‐net‐shaped parts from a powder bed. A very promising application of PBF lies in the direct control of the resulting microstructure by adjusting process parameters. Especially the intentional tilting of grains in one certain direction offers a complete...

The recent success of the process monitoring method Electron Optical Imaging, applied in the additive manufacturing process Electron Beam Powder Bed Fusion, necessitates a clear understanding of the underlying image formation process. Newly developed multi-detector systems enable the reconstruction of the build surface topography in-situ but add co...

The smoke phenomenon that happens during Electron Beam Powder Bed Fusion is recorded using an Electron-Optical monitoring system (detection of backscattered electrons during PBF-EB) for the first time. Furthermore, investigations with a high-speed camera show that smoke is a process that can involve multiple stages. The changes within the powde...

One major advantage of additive manufacturing is the high freedom of design, which supports the fabrication of complex structures. However, geometrical features such as combined massive volumes and cellular structures in such parts can lead to an uneven heat distribution during processing, resulting in different material properties throughout the p...

This paper introduces a multiscale and multi-purpose simulation framework to investigate selective beam melting processes for metallic cellular structures along the complete process chain, up to the topology optimization of components made of cellular materials. Process simulation methods on various length scales are introduced to analyze the relat...

Spontaneous infiltration of a porous preform by a metallic melt provides the potential of generating metal matrix composites (MMCs) with tailored combinations of material properties at low cost. The bulk of tool inserts for injection molding must sustain high mechanical and thermal loads and simultaneously exhibit high thermal conductivity for effi...

Advantages of 150 kV acceleration voltage for PBF-EB.

Presentation about the advantages of a higher acceleration voltage and electron optics for PBF-EB

In the current work we employ multi-phase-field simulations to understand the effect of remelting on microstructure evolution, especially on nucleation of new grains during selective electron beam melting (SEBM) of Ni-based super alloy. The phase-field model is coupled to both mass and heat transport phenomena including release of latent heat of so...

Introducing Cu nanoparticles is an effective mechanism for strengthening and toughening Fe‐based materials such as ultra‐high‐strength steels. Herein, the effect of Cu on the mechanical properties of a novel Fe‐based α/α′/α″ superalloy is studied. Compared to a Cu‐free reference alloy, nanoindentation reveals an increase in hardness, which was asso...

Well-established non-destructive testing methods in aero engine industry are time-consuming and expensive with a negative impact on economic viability, especially for parts from additive manufacturing. To improve the economics of electron beam powder bed fusion (PBF-EB), the detection and evaluation of backscattered electrons (BSEs) during the PBF-...

Due to the limitations of current in vivo experimental designs, our comprehensive knowledge of vascular development and its implications for the development of large-scale engineered tissue constructs is very limited. Therefore, the purpose of this study was to develop unique in vivo imaging chambers that allow the live visualization of cellular pr...

Fatigue properties of a 4th generation Titanium Aluminide alloy processed via electron-based powder bed fusion

Influence of the acceleration voltage on processing Ti-6Al-4V on an prototyp large chamber electron-based powder bed fusion machine

This is a correction to "Yang, Z., Bauereiß, A., Markl, M. and Körner, C. (2021), Modeling Laser Beam Absorption of Metal Alloys at High Temperatures for Selective Laser Melting. Adv. Eng. Mater., 23: 2100137. https://doi.org/10.1002/adem.202100137"

Numerical methods can accelerate the design of alloys with improved material properties. One approach is the coupling of multi-criteria optimization with CALPHAD-based models of alloy properties. While this technique has already yielded promising new Nickel-base superalloys, the applicability to CoNi-base alloys has not yet been investigated. These...

The design freedom in Laser Metal Deposition provided by the absence of a powder bed enables the fabrication of Functionally Graded Materials through Additive Manufacturing. For the first time, two suitable γ-TiAl alloys (TiAl48Cr2Nb2, TiAl45Nb4C) are combined in direct and gradual transitions to generate different microstructure morphologies and,...