Additive manufacturing by selective laser melting (SLM) was used to investigate the effect of laser energy density on 316L stainless steel properties. Point distance and exposure time were varied and their impact on porosity, surface finish, microstructure, density and hardness, was evaluated. The surface roughness was primarily affected by point distance with increased point distance resulting in increased surface roughness, R a , from 10 to 16 μm. Material hardness reached a maximum of 225 HV at 125 J/mm 3 and was related to the material porosity; with increased porosity leading to decreased material hardness. Different types of particle coalescence leading to convex surface features were observed (sometimes referred to as balling); from small ball features at low laser energy density to a mixture of both small and large ball features at high laser energy density. Laser energy density was shown to affect total porosity. The minimum amount of porosity, 0.38 %, was observed at an energy density of 104.52 J/mm 3 .

Since the discovery of the record figure of merit (ZT) of 2.6 ± 0.3 in tin selenide (SnSe), the material has attracted much attention in the field of thermoelectrics. This paper reports a novel pseudo‐3D printing technique to fabricate bulk SnSe thermoelectric elements, allowing for the fabrication of standard configuration thermoelectric generators. In contrast to fabrication examples presented to date, this technique is potentially very low‐cost and allows for facile, scalable, and rapid fabrication. Bulk SnSe thermoelectric elements are produced and characterized over a wide range of temperatures. An element printed from an ink with 4% organic binder produces the highest performance, with a ZT value of 1.7 (±0.25) at 758 K. This is the highest ZT reported of any printed thermoelectric material, and the first bulk printed material to operate at this temperature. Finally, a proof‐of‐concept, all printed SnSe thermoelectric generator is presented, producing 20 µW at 772 K.

Powder Bed Additive Manufacturing offers unique advantages in terms of manufacturing cost, lot size and product complexity compared to traditional processes such as casting, where a minimum lot size is mandatory to achieve economic competitiveness. Many studies -both experimental and numerical -are dedicated to the analysis of how process parameters such as heat source power, scan speed and scan strategy affect the final material properties. Apart from the general urge to increase the build rate using thicker powder layers, the coating process and how the powder is distributed on the processing table has receive27d very little attention to date. This paper focuses on the first step of every powder bed build process: Coating the process table. A numerical study is performed to investigate how powder is transferred from the source to the processing table. A solid coating blade is modelled to spread commercial Ti-6Al-4V powder. The resulting powder layer is analyzed statistically to determine the packing density and its variation across the processing table. The results are compared with literature reports using so called "rain" models. A parameter study is performed to identify the influence of process table displacement and wiper velocity on the powder distribution. The achieved packing density and how that affects subsequent heat source interaction with the powder bed is also investigated numerically.

Effects of hot isostatic pressing on the elastic modulus and tensile properties of 316L parts made by powder bed laser f u s i o n , Materials Science & Engineering A,

The emergence of bulk metallic glasses and their identification as versatile advanced engineering materials with attractive properties has led to a surge in research efforts to investigate processing methods, which can be used either to synthesise new BMG alloys or to shape BMG workpieces into final components with specific geometries. Among such technologies, the number of studies focussing on the laser processing of BMGs has gradually increased over the past decade. For this reason, a comprehensive summary of the state-of-the-art in this particular field of research is presented in this review. The reported studies are categorised into the different laser applications that have been proposed so far by the research community, namely the welding, cladding, additive layer manufacturing, micro machining and microstructure modification of BMG substrates. Due to the attractive properties of BMGs stemming from their amorphous nature, results are also presented, when available, concerning the effect of laser irradiation on the generation of crystalline precipitates during processing and the effect of these changes on the resulting material properties. This review has identified a number of gaps in the knowledge surrounding the laser processing of bulk metallic glasses. Understanding the fundamental interaction of laser energy with multi-component alloys will be necessary, as the development of lasers continues and the amount of available A c c e p t e d M a n u s c r i p t bulk metallic glasses increases. In particular, the crystallisation kinetics of bulk metallic glasses during laser irradiation needs to be understood to aid in the development and optimisation of processes such as welding and cladding. This could be helped by created an accurate simulation model to predict the onset of crystallisation although this is not a minor challenge, developing a complete temperature field model during laser irradiation is a complex task when considering vaporisation, plasma effects as well as chemical composition changes in the material. Besides, there is also the issue of variations in material properties as the temperature increases, particularly for BMGs whose temperature dependent properties are not well-documented. The research into the additive layer manufacturing of bulk metallic glass should continue to grow. Parametric effects need to be addressed to complete the optimisation of this process. Further investigations of the resulting crystallisation processes upon repeated melting and solidification should also aid in the process being able to be controlled more effectively. Finally, the use of laser processing of bulk metallic glass for specific application needs to be investigated further.

The standard power law approaches widely used to describe creep and creep fracture behavior have not led to theories capable of predicting long-term data. Similarly, traditional parametric methods for property rationalization also have limited predictive capabilities. In contrast, quantifying the shapes of short-term creep curves using the q methodology introduces several physically-meaningful procedures for creep data rationalization and prediction, which allow straightforward estimation of the 100,000 hour stress rupture values for the aluminum alloy, 2124.

Despite its excellent elemental properties, lightweight nature and good alloying potential, scandium has received relatively little attention in the manufacturing community. The abundance of scandium in the Earth's crust is quite high. It is more abundant than silver, cobalt, lead and tin. But, because scandium is so well dispersed in the lithosphere, it is notoriously difficult to extract in commercial quantities-hence low market availability and high cost. Scandium metallurgy is still a largely unexplored field-but progress is being made. This review aims to summarise advances in scandium metallurgical research over the last decade. The use of scandium as a conventional minor addition to alloys, largely in structural applications, is described. Also, more futuristic functional applications are discussed where details of crystal structures and peculiar symmetries are often of major importance. This review also includes data obtained from more obscure sources (especially Russian publications) which are much less accessible to the wider community. It is clear that more fundamental research is required to elevate the status of scandium from a laboratorybased curiosity to a mainstream alloying element. This is largely uncharted territory. There is much to be discovered.

Bulk non-toxic and Earth abundant Cu2−xS is pseudo-3D printed in a low-cost method yielding ZT values of up to 0.63.