Over the past few years, additive manufacturing (AM) has attracted much attention, owing to the promise for direct printing of parts with complex-shapes which would not be possible to machine using more conventional methods. AM is more commonly referred to as 3D printing and its name originates from the nature of the process that consists in successively depositing a material that is locally melted on the top surface of the sample to add a new layer. For metals, this is achieved by selectively melting a powder deposited via one or more nozzles located near the sample surface, using an energetic electron or laser beam.

Whether additive manufacturing delivers on its promises or not, the structure-property relationships of parts fabricated following this route need to be investigated. AM also offers completely new alternatives to design compositionally-graded materials by changing the powder used during the fabrication. From a materials science perspective, the microstructures from electron- or laser-melting the structures observed are rather close to those obtained from rapidly solidified materials during, for example, welding.

A selection of articles among the most highly downloaded this year has been made free to download and can be found below, including an overview article:

Overview: Additive manufacturing of metals

Coupling electron beam melting and spark plasma sintering: A new processing route for achieving titanium architectured microstructures.

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

Normalised model-based processing diagrams for additive layer manufacture of engineering alloys

Effect of processing parameters on microstructure and tensile properties of austenitic stainless steel 304L made by directed energy deposition additive manufacturing

Denudation of metal powder layers in laser powder bed fusion processes

Metallurgy of high-silicon steel parts produced using Selective Laser Melting

Effect of substrate preheating on the texture, phase and nanohardness of a Ti–45Al–2Cr–5Nb alloy processed by selective laser melting

The effect of defects on the mechanical response of Ti-6Al-4V cubic lattice structures fabricated by electron beam melting