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

The structure

3D printing of Aluminium alloys: Additive Manufacturing of Aluminium alloys using selective laser melting

Review on superior strength and enhanced ductility of metallic nanomaterials

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. This is true for AM-produced steels just as it is for conventionally-produced steels. However, steels are subjected during AM processing to time-temperature profiles which are very different from the ones encountered in conventional process routes, and hence the resulting microstructures differ strongly as well. This includes a very fine and highly morphologically and crystallographically textured microstructure as a result of high solidification rates as well as non-equilibrium phases in the as-processed state. Such a microstructure, in turn, necessitates additional or adapted post-AM heat treatments and alloy design adjustments. In this review, we give an overview over the different kinds of steels in use in fusion-based AM processes and present their microstructures, their mechanical and corrosion properties, their heat treatments and their intended applications. This includes austenitic, duplex, martensitic and precipitation-hardening stainless steels, TRIP/TWIP steels, maraging and carbon-bearing tool steels and ODS steels. We identify areas with missing information in the literature and assess which properties of AM steels exceed those of conventionally-produced ones, or, conversely, which properties fall behind. We close our review with a short summary of iron-base alloys with functional properties and their application perspectives in Additive Manufacturing.

Steels in additive manufacturing: A review of their microstructure and properties

Ceftizoxime (FK749), a new cephalosporin with a potent in-vitro activity against Gram-negative bacilli

Laser powder bed fusion (L-PBF) is one of the additive manufacturing methods to produce metallic parts. The layer-by-layer manufacturing nature results in the formation of specific microstructure, achieving different properties compared to conventional analogs. In this chapter, the mechanical properties of the main classes of materials such as steels, aluminum and titanium alloys, as well as nickel-base superalloys manufactured by L-PBF are overviewed. The focus is on the static mechanical properties obtained by tensile tests as the most common standard method for the measurement of mechanical characteristics. A correlation between manufacturing, microstructure, and mechanical properties of these L-PBF materials is highlighted.

Structural integrity I: static mechanical properties

Joint strength of Fe/epoxy resin hybrid structure via porous Fe/TiB2 composite layer synthesized by in-situ reaction process

Synthesis and structural control of Fe-based porous layer on Fe substrate for joining with resin parts using combustion reaction

The lattice structure of the C14 Fe2Nb Laves phase with Ni in solution in Fe-Nb-Ni ternary alloys was examined by transmission electron microscopy. Binary stoichiometric Fe2Nb (Fe-33.3 at.% Nb) exhibits a featureless morphology with a low dislocation density. A similar morphology was observed in stoichiometric Fe2Nb containing 20 at.% Ni and in binary Fe-rich Fe2Nb (Fe-27.5 at.% Nb). In contrast, many planar faults parallel to the basal plane of the C14 structure were observed in Fe-rich Fe2Nb with Ni in solution, and the fault density increases with increasing Ni content up to 33.1 at.%. The high resolution transmission electron microscope (HRTEM) analysis revealed that the planar faults are related to the local change in the stacking sequence of the three 36-nets (triple layer) of the C14 structure. These results suggest that the presence of both, the point defects (Fe sublattice sites occupied by Ni atoms) and the anti-site defects (Nb sublattice sites occupied by excess Fe atoms), facilitate the formation of the planar faults.

Naoki Takata

Papers

Ceftizoxime (FK749), a new cephalosporin with a potent in-vitro activity against Gram-negative bacilli

Structural integrity I: static mechanical properties

Joint strength of Fe/epoxy resin hybrid structure via porous Fe/TiB2 composite layer synthesized by in-situ reaction process

Synthesis and structural control of Fe-based porous layer on Fe substrate for joining with resin parts using combustion reaction

Transmission Electron Microscopy of Fe 2 Nb Laves Phase with C14 structure in Fe-Nb-Ni Alloys