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

https://dc.engconfintl.org/cgi/viewcontent.cgi?article=1032&context=superalloys_ii

A critical review of high entropy alloys and related concepts

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

Plastic solid waste (PSW) of polymers (like: high density polyethylene (HDPE), low density polyethylene (LDPE), Nylon etc.) is creating new challenges, which in today's scenario are major research concerns. A sharp rise has been observed in production of different products based on different plastic material. This huge increase in plastic commodities also increases the waste generation thus creating new challenges. Some researchers have reported work in the field of PSW management with different recycling methods. This paper compiles the different research work done by researchers in this field of recycling and progress in recovery and management of PSW by different methods (i.e. Primary, secondary, tertiary and quaternary) along with the various identification/separation techniques. Further, this paper reviews the effect on properties of virgin and recycled HDPE/LDPE/Nylon PSW with different reinforcements like sand, natural fibre, hemp fibre, metal powder etc.

Recycling of plastic solid waste: A state of art review and future applications

High-entropy alloys (HEAs) are a relatively new class of materials that have gained considerable attention from the metallurgical research community over recent years They are characterised by their unconventional compositions, in that they are not based around a single major component, but rather comprise multiple principal alloying elements Four core effects have been proposed in HEAs: (1) the entropic stabilisation of solid solutions, (2) the severe distortion of their lattices, (3) sluggish diffusion kinetics and (4) that properties are derived from a cocktail effect By assessing these claims on the basis of existing experimental evidence in the literature, as well as classical metallurgical understanding, it is concluded that the significance of these effects may not be as great as initially believed The effect of entropic stabilisation does not appear to be overarching, insufficient evidence exists to establish the strain in the lattices of HEAs, and rapid precipitation observed in some HEAs sug

https://www.tandfonline.com/doi/pdf/10.1080/09506608.2016.1180020

High-entropy alloys: a critical assessment of their founding principles and future prospects

A critical appraisal of the extraction of creep parameters from nanoindentation data obtained at room temperature

Energy absorption in lattice structures in dynamics: Experiments

The article gives an review of the state-of-the-art for the Replication process as it is practiced for the production of microcellular metals or ceramics It includes a general description of the process and its variants and gives a brief overview of fundamentals, placing particular focus on pathways it offers for microstructural tailoring and control

Replication Processing of Highly Porous Materials

We employ additive manufacturing technologies for the design and fabrication of novel reinforcing elements of cement mortars. Three-point bending tests and optical microscope analyses are performed on a cement mortar reinforced with 3D printed fibers made of polymeric and metallic materials, which exhibit different surface morphology and roughness. Experimental and analytical results highlight that the shear capacity, flexural strength and fracture toughness of the examined materials greatly depend on the design and the material of the reinforcing fibers. Specimens reinforced with high surface roughness fibers exhibit shear failure and high interfacial bond strength, while unreinforced specimens and specimens reinforced with smooth fibers exhibit flexural failure and limited interfacial bond strength. We observe that mortar specimens reinforced with titanium alloy Ti6Al4V fibers exhibit load carrying capacity more than twice as high as specimens reinforced with photopolymeric fibers.

On the reinforcement of cement mortars through 3D printed polymeric and metallic fibers

Electron Beam Melting (EBM) is an Additive Manufacturing technique which can be used to fabricate complex structures from alloys such as Ti6Al4V, for example for orthopaedic applications. Here we describe the use of EBM for the fabrication of a novel Ti6Al4V structure of a regular diamond lattice incorporating graded porosity, achieved via changes in the strut cross section thickness. Scanning Electron Microscopy and micro computed tomography analysis confirmed that generally EBM reproduced the CAD design of the lattice well, although at smaller strut sizes the fabricated lattice produced thicker struts than the model. Mechanical characterisation of the lattice in uniaxial compression showed that its behaviour under compression along the direction of gradation can be predicted to good accuracy with a simple rule of mixtures approach, knowing the properties and the behaviour of its constituent layers.

Russell Goodall

Papers

A critical appraisal of the extraction of creep parameters from nanoindentation data obtained at room temperature

Energy absorption in lattice structures in dynamics: Experiments

Replication Processing of Highly Porous Materials

On the reinforcement of cement mortars through 3D printed polymeric and metallic fibers

Fabrication and Mechanical Characterisation of Titanium Lattices with Graded Porosity