The tip of the iceberg: EBM as an enabler of new materials in additive

This first technical essay in a three-part series developed with the UK’s National Centre for Additive Manufacturing explores the potential for Electron Beam Melting (EBM) and why it is the ideal technology to drive future materials development.

Download all three essays now

We see a lot of potential for EBM in the future of metal additive. Yet there are still only a few commercial materials on the market today that have been designed and tailored for EBM. We expect that to change rapidly due to rapid technological advancements and increased industry awareness of EBM and its capabilities.

Today, over 80 alloys that have already been used with EBM in the academic world and in industry could be developed further for commercial applications.

Some of these materials are hard metals such as NiWC, beryllium (AlBeMet), amorphous metals, refractory metals such niobium and tungsten and entropy alloys. And these are just the ones we currently know about. There could be – and are likely to be – many more that will come to fruition as there are little to no technical limitations to realizing and using these materials. The main barrier to realizing more materials in additive parts is market demand.

Developing materials for any additive modality can be a costly, time-consuming process, and there needs to be an interest from the market to develop a material for an application. Without market demand, or market interest at the very least, materials are unlikely to be developed. Many additive users have different preferences for what alloys to use even for similar applications, and in terms of parameter sets one size does not fit all. So, out of all the available alloys, which one to develop?

Business sense has prevailed across industry regarding where and how EBM should be used, but with an increase in demand, it is likely that we will see its use growing for more applications, especially across highly regulated industries. And indeed, there is also a lot of interest from the automotive, healthcare and aerospace sectors – all early adopters of metal additive – but there is also a lot of potential for EBM across most other industries.

From a scientific and technical perspective, we are only at the tip of the iceberg with EBM. Yet, there are many things that we could do to bring more EBM-tailored materials to the market. We are now at the stage where research and academic institutes are helping bridge the supplier-industry gap, but more end-users need to come forward with their requirements and applications to really showcase the commercial potential of EBM.

At GE Additive we try to ensure that we provide specific requirements and focus areas to our research and academic institute partners to help them be more efficient when identifying which research to target.

Emerging Trends Drive Emerging Materials

There are many scenarios where EBM is beneficial over other additive modalities, and like any technology, there are scenarios where it is not wise to use EBM. It goes without saying that with metal additive, both high-quality powder and an efficient machine are required, and if only one exists, then the desired results may not be achieved. Therefore, there is a big drive to develop systems and materials for EBM in parallel.

When it comes to using additive manufacturing to print a part, users already have several benefits at their disposal over conventional manufacturing methods, such as the ability to print parts or to create parts with complex geometries and unique microstructures, which may be difficult to achieve via traditional means.

Beyond general additive benefits, there are also benefits that are specific to the operations of EBM. One of the main features of EBM is its vacuum environment. Building parts in a high-temperature vacuum environment can be a huge benefit for some alloys, but a detriment for others.

The elevated processing temperature of EBM can help reduce residual stress in some materials, which enables “exotic” materials – such as high temperature nickel alloys – to be used, but it can also vaporize elements in some alloys. So, it is crucial with EBM to know which materials are going to work best. Copper is a great example of a material that works well with EBM, since the vacuum atmosphere reduces oxygen pick-up and contamination in the consolidated material. Additionally, unlike other additive modalities, EBM can handle high-purity copper alloys, opening up copper additive parts to more demanding applications.

On the other side of the spectrum, there is demand in the market for crack prone aluminum alloys and other volatile elements. At first glance, they look like they would be suitable materials for EBM. However, in the case of zinc, once the temperature in EBM’s vacuum environment is elevated, zinc ions are going to evaporate, get widely dispersed and damage the vacuum system.

Knowing the material capability of your system is key to ensuring you get the right part for your application, which stems from fundamental research and development. There are several different alloy types that are suitable for EBM, including copper, highly alloyed tool steels, aluminum and metal-matrix composites, to name just a few.

This list will likely be expanded further by the development of tailored EBM-alloys using the technology’s unique characteristics, as opposed to simply additively manufacturing alloys that are traditionally cast to get comparable properties.

It might even be possible to revisit the chemistry of said traditional alloys not suitable for EBM as-is in order to get similar or better properties, but vastly improve processability under vacuum and high temperatures. This could in turn open the door to the crack-prone aluminum alloys mentioned above and other alloys not suitable to process in EBM today.

EBM technology (and suitable materials) has continuously improved over the years, and it can serve different fields of application and different materials alongside other additive modalities. Today, EBM can and should be seen as a complementary technique to other powder bed fusion additive modalities, rather than a competing technology.

"The processing capability of an EB-PBF system, such as the Arcam EBM system, brings multiple benefits that constrain other processes such as LB-PBF. The ability to utilize productionized equipment that have elevated temperature control in conjunction with a vacuum system enables a variety of possibilities which are really exciting in the AM materials and application world. That combination opens the door for taking novel material research and applying it in production, much like we saw in Avio Aero with TiAl." — Ruaridh Mitchinson, Senior Research Engineer at the National Centre for Additive Manufacturing (NCAM)

Key Markets for EBM

Given that EBM can be used to produce high-performance parts from high-performance materials at elevated temperatures, coupled with the ability to build bulky and typically difficult-to-print parts, key markets today include the aerospace and the medical industries. However, there is the untapped potential for EBM to be used in energy, power, and oil & gas, among others.

We currently see a lot of interest in using EBM from these sectors. On one hand, this is being driven by the wider shift in many industries towards electrification. On the other hand, as metal additive users mature and become more advanced, the desire to innovate and develop extreme-environment applications, such as busbars that can fill internal voids within an engine or hot-zone components, is growing. The material demands in most sectors are also becoming greater as each application area develops. EBM offers a way of meeting that continued demand, as well as offering new capabilities in many other industrial sectors.

The Role of Academia in EBM’s Success

Today, many Arcam EBM machines are installed within research and academic institutes and universities around the world. Academia has played and continues to play a huge role in the success and development of EBM. Arcam EBM, as a company, is a product of the academic system and is a spin-off of Chalmers University of Technology in Sweden, before being acquired by GE Additive in 2016. Academia is a hotbed of fundamental research and development as well as understanding how to harness this technology to better the industry. Going forward, academia will play a key role in the advancement of EBM - and of course, for the wider additive industry. One key aspect of academia is the interdisciplinary nature of the working environment. Lots of people working together, globally, can draw on each other’s experience, networks and expertise - often across different fields - to tackle different challenges.

As EBM enters new markets, it is this kind of industry and research and academic collaboration that can initially open the door. These organizations can showcase the potential for different applications without industry needing to invest in cost-intensive and time-consuming development protocols. However, it will require more than just publishing academic papers to realize the commercial feasibility of many applications. It is going to take a synergistic approach between industry and academia where collaboration can happen, and data can be shared at all levels for the benefit of industry. Drawing on expertise on both sides will enable additive technology manufacturers to attempt new EBM operations in different sectors and provide academics and researchers the ability to undertake novel projects. In these synergistic scenarios, there is mutual advancement that can benefit academics, additive technology manufacturers, and end-users alike. Fostering open collaboration is already something that the wider EBM community does very well.

The Power of Community

Those who are familiar with both academia and industry understand that there is often a “valley of death” that separates academic discovery and commercial reality, where even the best technologies can be lost during the transfer.

Bridging academia can be a challenge, regardless of the industry, technology, or scientific field. However, the EBM community is close knit, which makes it easier to build those bridges. GE Additive has been proactive in launching training programs where researchers are trained to use the EBM machines to develop new capabilities or have adopted a two-party, joint-program approach.

Over the years, these training programs have been successful in developing new materials and EBM technology strategies. There are plans for these training programs to be opened to the wider academic community, which will further advance EBM into new, promising sectors. Another way to bridge the gap between academia and industry is through leading research institutes like the National Centre for Additive Manufacturing (NCAM) based at the Manufacturing Technology Centre (MTC) in the UK and the Oak Ridge National Laboratory (ORNL) in the United States.

Not only can institutes like NCAM and ORNL facilitate dialogue between interested parties, but their own research activities can also help provide feasibility data to industrial partners looking to invest in an EBM application. Rather than simply adopting a plug-and-play approach, this allows an intermediary partner to optimize and modify the process so that it’s better suited to the end-use requirements.

"Most recently NCAM has been collaborating with an aerospace company to design, set-up and operate an AM pre-production facility (based at the MTC) that supplied over two hundred Ti6Al4V engine components. Providing the aerospace company with a de-risked R&D environment that led to the accelerated optimization of the EBM process, pushing the boundaries of the maximum part size which enabled benefits such as further part consolidation and enhanced part functionality for the customer. Demonstrating that not only can collaboration make commercial sense but also bring key technical benefits to fruition." — Ruaridh Mitchinson, Senior Research Engineer at the National Centre for Additive Manufacturing (NCAM).

Overall, close collaboration is the best strategy for all parties to communicate their requirements, which will more quickly determine whether EBM is the appropriate method for a given application.

In an ideal scenario, the future of the EBM community will be governed by a consortium that helps to communicate the needs of the academic community and end users so that the material and equipment suppliers can best meet the needs of all parties.

Open transparency and communication between organizations could lead to a more efficient development progress that would advance the entire industry.

Looking to the Future

GE Additive believes that there is significant potential for EBM in a wide variety of industrial sectors and end-use applications and that it will continue to gain momentum as a powerful additive modality. There are already over 80 high-performance materials that are suitable with EBM, a number that is constantly growing. That demonstrates that the science, in particular the materials science, behind EBM is sound and that our fundamental approach can be leveraged by academic researchers to advance the field.

Developing new materials for commercial use is a significant undertaking and the business case must be justified based on real potential applications. This again reinforces the need for users, academia, and suppliers to work closely to focus development on materials that will have the widest and furthest impact.

With this knowledge, OEMs in the growing EBM space, like GE Additive, will be in a much better position to supply equipment and materials that will meet the needs of customers. This method of open and transparent development could be key to unlocking EBM in new market sectors, as well as improving penetration in existing markets.

Coming soon: Stretching copper to its limits. Download all three essays here now.