There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Additive manufacturing of metallic components – Process, structure and properties

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

Additive manufacturing of metals

Herstellung flächiger Leichtbauteile durch Umgießen von Aluminium‐Schäumen im Druckgießverfahren

Fabrication of parts by metal injection molding (MIM) results in very fine grain sizes. In the present investigation, heat treatments were employed to gain a larger grain size that is more creep resistant. The alloy under investigation was CM 247 LC. The composition was slightly modified to facilitate grain growth. Secondary recrystallization was observed to occur during post-sintering annealing treatments approximately 50 °C below the sintering temperature. The grain size increased from 25 µm to > 2 mm. The increase of grain size was found to improve creep strength significantly. The samples in the as-sintered condition exhibited a bimodal grain size distribution. The grain size in a thin surface zone after sintering was slightly increased because of a lower C and O content in this zone that promoted normal grain growth. Secondary recrystallization did not occur in the surface zone. This is attributed to a lack of driving force in this area.

Secondary Recrystallization of Nickel-Base Superalloy CM 247 LC After Processing by Metal Injection Molding

Gaseous nitriding of Co-10 at.% and -15 at.% Cr alloys at 400 °C and 450 °C

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 new field of activity for additively produced parts specially designed for a given load case. Nucleation is essential for utilization of this effect. Herein, an alternative approach for modeling nucleation in PBF of metals is introduced. The model is not intended to cover every physical effect of this extreme complex phenomenon. Based on observations reported from different researchers in the field of PBF, a heuristic approach is applied to consider new grains within a cellular automata (CA)‐based crystal growth model for PBF. Utilizing the implicit capability of the CA to model competitive growth of grains, this approach does not require any additional computational capacities. The numerical calculations are carried out using a message–passing interface (MPI) parallelization on a high‐performance computing (HPC) cluster located at the Regional Research Center Erlangen. The numerical results are validated by means of experiments and electron backscatter diffractometric measurements.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/adem.202201682

Carolin Körner

Papers

Herstellung flächiger Leichtbauteile durch Umgießen von Aluminium‐Schäumen im Druckgießverfahren

Secondary Recrystallization of Nickel-Base Superalloy CM 247 LC After Processing by Metal Injection Molding

Gaseous nitriding of Co-10 at.% and -15 at.% Cr alloys at 400 °C and 450 °C

Alternative Approach to Modeling of Nucleation and Remelting in Powder Bed Fusion Additive Manufacturing

Selective Electron Beam Melting: A new Way to Auxetic Cellular Structures