Philipp Kürnsteiner

• PhD
• PostDoc Position at Johannes Kepler University of Linz

Due to the layer-by-layer build-up of additively manufactured parts, the deposited material experiences a cyclic re-heating in the form of a sequence of temperature pulses. In the current work, this “intrinsic heat treatment (IHT)” was exploited to induce the precipitation of NiAl nanoparticles in an Fe-19Ni-xAl (at%) model maraging steel, a system...

Today, a large number of different steels are being processed by Additive Manufacturing (AM) methods. The different matrix microstructure components and phases (austenite, ferrite, martensite) and the various precipitation phases (intermetallic precipitates, carbides) lend a huge variability in microstructure and properties to this class of alloys....

Laser additive manufacturing is attractive for the production of complex, three-dimensional parts from metallic powder using a computer-aided design model1,2,3. The approach enables the digital control of the processing parameters and thus the resulting alloy’s microstructure, for example, by using high cooling rates and cyclic re-heating4,5,6,7,8,...

Laser Additive Manufacturing (LAM) of light metals such as high-strength Al-based alloys offers tremendous potential for e.g. weight reduction and associated reduced fuel consumptions for the transportation industry. Typically, commercial Sc-containing alloys, such as Scalmalloy®, rely on precipitation hardening to increase their strength. Conventi...

Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure—in particular the content of retained and reversed austenite as well as...

Grain boundary wetting as a preliminary stage for zinc-induced grain boundary weakening and embrittlement in a Zn-coated press-hardened 20MnB8 steel was analyzed using electron backscatter diffraction, Auger electron spectroscopy, energy dispersive X-ray analysis, atom probe tomography and transmission electron microscopy. Microcracks at prior aust...

The formation of thermally stable intermetallic phases plays a key role to enable high temperature applications for Mg alloys. In the ductile Mg-Al-Ca system, Ca-rich Laves phases are expected to be crucial for improving high temperature mechanical properties. However, the formation mechanisms of Ca-rich Laves phases are still unresolved. Here, we...

The development of a composite microstructure with hard aluminum nitrides (AlN) dispersed in a soft ferritic iron‐based solid is achieved through the powder metallurgy route. Fe‐4.6 at% Al alloy powders subjected to two different thermochemical treatments viz. nitriding and nitriding followed by hydrogen reduction are consolidated by spark plasma s...

By using laser powder bed fusion (LPBF) in the tooling industry, tools with complex geometries and integrated functions, such as adapted cooling channels, can be manufactured with high potential in terms of product lifetimes or cycle times. When processing tool steels with a carbon content > 0.6 wt.-% by means of LPBF, hard and brittle phases are f...

Fe nitrides are highly important for the surface engineering of steels and cast irons, and interesting functional materials. The effect of Si on the formation and growth of Fe nitrides is insufficiently understood. No quantitative data on the Si solubility in the most prominent ε and γ' Fe nitrides exist. In this study, the formation and growth of...

Oxide dispersion strengthened (ODS) steels are known for their enhanced mechanical performance at high temperatures or under radiation exposure. Their microstructure depends on the manufacturing process, from the nanoparticle addition to the base steel powder, to the processing of the nanoparticle enriched powder. The optimization and control of th...

The capability of high-pressure torsion on the preparation of supersaturated solid solutions, consisting of Cu-14Fe (wt.%), is studied. From microstructural investigations a steady state is obtained with nanocrystalline grains. The as-deformed state is analyzed with atom probe tomography, revealing an enhanced solubility and the presence of Fe-rich...

open access links: https://link.springer.com/article/10.1007%2Fs11661-020-05947-2 https://rdcu.be/b6P8O https://doi.org/10.1007/s11661-020-05947-2 This is a viewpoint paper on recent progress in the understanding of the microstructure–property relations of advanced high-strength steels (AHSS). These alloys constitute a class of high-strength, for...

In this contribution, the effect of nanoparticle additivation on the microstructure and microhardness of oxide dispersion strengthened steels (ODS) manufactured by laser powder bed fusion (L-PBF) and directed energy deposition (DED) additive manufacturing (AM) is studied. The powder composites are made of micrometer-sized iron-chromium-alloy based...

The interactions of solutesSolutes with crystal defectsCrystal defects at near-atomic-level were investigated in five single-crystal nickel-based superalloys deformed at temperatures between 850 and 1160 °C and various deformationDeformation conditions. These interactions, and consequently the composition of a particular soluteSolutes that segregat...

In this work an unexplored method of utilization of gaseous nitriding of Fe-2.3 wt% Al alloy powders was employed to realize a dispersion of nanosized AlN particles in the ferritic matrix. The nitriding treatment was carried out at 580 °C in ammonia atmosphere and the resulting microstructures were characterized by employing light microscopy, scann...

The capability of high-pressure torsion on the preparation of supersaturated solid solutions, consisting of Cu-14Fe (wt.%), is studied. From microstructural investigations a steady state is obtained with nanocrystalline grains. The as-deformed state is analyzed with atom probe tomography, revealing an enhanced solubility and the presence of Fe-rich...

Crack initiation mechanisms in the very high cycle fatigue (VHCF) regime of nickel-based single-crystal (SX) superalloys have been investigated at high temperature (1000 °C) and under fully reversed conditions (R = −1). For all Ni-based SX alloys tested, a discernible area called rough zone has been identified around the crack initiation site on th...

Application of Atom Probe Tomography to Complex Microstructures of Laser Additively Manufactured Samples - Volume 25 Supplement - Philipp Kürnsteiner, Avinash Hariharan, Hyo Yun Jung, Nicolas Peter, Markus Benjamin Wilms, Andreas Weisheit, Pere Barriobero-Vila, Baptiste Gault, Dierk Raabe, Eric Aimé Jägle

Additive manufacturing, or 3D printing, has brought tremendous opportunities for the design and making of metallic components with high geometrical complexity. However, in order to maximize the performance and functionality of a specific part, the additive manufacturing industry currently still faces fundamental issues of material processability an...

The microstructure and phase composition in selective laser melted (SLM) Ti-6Al-4V plays a key role for its mechanical performance. The microstructure evolution in SLM Ti-6Al-4V was studied in the as-built condition and after sub-transus heat treatments between 400 °C and 800 °C focusing on elemental partitioning and the role of lattice defects on...

The microstructure and phase composition in selective laser melted (SLM) Ti-6Al-4V plays a key role for its mechanical performance. The microstructure evolution in SLM Ti-6Al-4V was studied in the as-built condition and after sub-transus heat treatments between 400 °C and 800 °C focusing on elemental partitioning and the role of lattice defects on...

Additive Fertigung (Additive Manufacturing - AM) ist eine Technologie mit enormem Potenzial, jedoch auch hoher Komplexität. Im Gegensatz zu herkömmlichen Fertigungsansätzen ist AM sehr interdisziplinär und erfordert eine zusammenhängende Betrachtung der AM-Prozesse, des AM-konformen Designs und Engineerings, von Baustrategien, Nachbehandlungen und...

Atom probe tomography (APT) is rising in influence across many parts of materials science and engineering thanks to its unique combination of highly sensitive composition measurement and three-dimensional microstructural characterization. In this invited article, we have selected a few recent applications that showcase the unique capacity of APT to...

A twinning induced plasticity (TWIP) steel, developed for automotive applications, was characterized down to the nanoscale to investigate the nature of the strengthening mechanisms. Both tensile-deformed and non-deformed materials were studied by light optical microscopy, X-ray diffraction, electron backscatter diffraction, and transmission electro...

Ti and its alloys have a high affinity for hydrogen and are typical hydride formers. Ti-hydride are brittle phases which probably cause premature failure of Ti-alloys. Here, we used atom probe tomography and electron microscopy to investigate the hydrogen distribution in a set of specimens of commercially pure Ti, model and commercial Ti-alloys. Al...

Ti and its alloys have a high affinity for hydrogen and are typical hydride formers. Ti-hydride are brittle phases which probably cause premature failure of Ti-alloys. Here, we used atom probe tomography and electron microscopy to investigate the hydrogen distribution in a set of specimens of commercially pure Ti, model and commercial Ti-alloys. Al...

Ti has a high affinity for hydrogen and is a typical hydride formers. Ti-hydride are brittle phases which probably cause premature failure of Ti-alloys. Here, we used atom probe tomography and electron microscopy to investigate the hydrogen distribution in a set of specimens of commercially pure Ti, model and commercial Ti-alloys. Although likely p...

Atom probe tomography (APT) is rising in influence across many parts of materials science and engineering thanks to its unique combination of highly sensitive composition measurement and three-dimensional microstructural characterization. In this invited article, we have selected a few recent applications that showcase the unique capacity of APT to...

In-process Precipitation During Laser Additive Manufacturing Investigated by Atom Probe Tomography - Volume 23 Issue S1 - Philipp Kürnsteiner, Markus Benjamin Wilms, Andreas Weisheit, Pere Barriobero-Vila, Baptiste Gault, Eric Aimé Jägle, Dierk Raabe

Depth profiling using surface sensitive analysis methods in combination with sputter ion etching is a common procedure for thorough material investigations, where clean surfaces free of any contamination are essential. Hence, surface analytic studies are mostly performed under ultra-high vacuum (UHV) conditions, but the cleanness of such UHV enviro...

Due to the layer-by-layer build-up of additively manufactured parts, the deposited material experiences a cyclic re-heating in the form of a sequence of temperature pulses. In the current work, this “intrinsic heat treatment (IHT)” was exploited to induce the precipitation of NiAl nanoparticles in an Fe-19Ni-xAl (at%) model maraging steel, a system...

Due to the layer-by-layer build-up of additively manufactured parts, the deposited material experiences a cyclic re-heating in the form of a sequence of temperature pulses. In the current work, this “intrinsic heat treatment (IHT)” was exploited to induce the precipitation of NiAl nanoparticles in an Fe-19Ni-xAl (at%) model maraging steel, a system...

Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure—in particular the content of retained and reversed austenite as well as...

Charge exchange between He ions and a Ni(111) surface containing oxygen was studied by Low-Energy Ion Scattering, using 1.25 keV He+ as primary ions. The energy resolved yield of positive ions was detected after backscattering from Ni or O for different exposures of Ni(111) to molecular oxygen. Pronounced changes in the neutralization efficiency du...