By late spring 2020 the Covid-19 pandemic had caused virtually all international conferences and exhibitions to be canceled or postponed to the following year. As a result MPR is able to give more space to important but as yet unreported contributions from 2019.

One such instance played an important part across two sessions of the EPMA 2019 Annual Congress, where experts in the fields of hard materials and additive manufacturing jointly studied the interlocking status of their respective arts.

So what is so special about AM-HM?

The typical raw material for additive manufacturing, colloquially ‘3D printing,’ is plastic or metallic, melts within a small temperature range and welds strongly to the previously melted material. Hardmetals, on the other hand, comprise two wildly different materials: particles of hard and wear-resistant ceramic, typically but not exclusively tungsten carbide (WC), embedded in a tough metallic matrix such as cobalt (Co). The ceramic WC melts at nearly 2800 °C, whilst the melting point of pure cobalt is about 1500 °C. In traditional PM, moreover, the WC doesn’t melt, but partially dissolves and reprecipitates from the matrix during liquid-phase sintering. At just above the WC melting point, pure Co is vaporized.

No wonder that hardmetal AM has been so long in coming, and rated not one but two special sessions at the EPMA Maastricht event. The first of these concentrated on fusion processes whilst the second trained its sights on more indirect methods. Most of the papers described relatively simple WC/Co alloys, but there were exceptions looking at more complex compositions. They are reviewed in order of presentation.

This article appeared in the July–August 2020 issue of Metal Powder Report. Log in to your free materialstoday.com profile to access the article.

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