Four Best Poster Awards for Research into Nanomechanical Testing

Max Planck materials scientists recognised for their research on 3D-printed metals, hydrogen-induced deformation and fracture behaviour at the microscale

At a glance:

• Awards: Four Best Poster Awards for Nhat Hoang Van (1st place), Alvaro Diego Bedoya Zapata (2nd place), Kaili Feng (2nd place) and Jeongin Paeng (2nd place) from the Max Planck Institute for Sustainable Materials
• Conference: ECI Nanomechanical Testing in Materials Research and Development X, which took place from October 4-9 in Rhodes, Greece
• Research fields: Nanomechanical testing, additive manufacturing, microstructure-property relationships, hydrogen-induced deformation and fracture behaviour

 

Four researchers from the Max Planck Institute for Sustainable Materials (MPI-SusMat) received Best Poster Awards at the ECI Nanomechanical Testing in Materials Research and Development X conference, which took place from October 4-9 in Rhodes, Greece. Their research explores how materials behave under mechanical stress at the micro- and nanoscale, from the performance of 3D-printed copper devices to the influence of hydrogen on steel.

3D-printed copper devices for next-generation microsystems

1st place: Nhat Hoang Van

Micro-electromechanical systems (MEMS) are miniature devices that combine mechanical and electrical components. They are used in technologies ranging from motion sensors to precision measurement instruments. Conventional manufacturing methods, however, involve complex processes and largely restrict these devices to planar geometries.

Nhat Hoang Van, PhD researcher at MPI-SusMat, is exploring a more flexible manufacturing approach: 3D printing functional copper MEMS devices using localised electrodeposition, a technique that builds metallic structures by depositing copper from a liquid. This method enables complex three-dimensional geometries to be produced in a single step. Hoang Van demonstrated its potential by fabricating miniature actuators capable of linear and rotational movement. He also investigated how the electrical properties of 3D-printed copper change under mechanical stress. Using a specially developed testing setup inside a scanning electron microscope, Hoang Van measured the electrical resistance of microscopic copper pillars during compression. The experiments revealed that electrical resistivity increases as the pillars deform, regardless of whether they have micro- or nanostructured internal features.

How microstructure and deformation speed affect 3D-printed copper

2nd place: Álvaro Diego Bedoya Zapata

3D printing allows to manufacture microscopic metallic structures with complex geometries. However, their mechanical performance depends not only on their shape but also on the internal structure of the metal itself. Understanding how these tiny components behave under different loading conditions is essential for developing reliable metallic microdevices as used in microsensors or smartphones.

Álvaro Diego Bedoya Zapata, PhD researcher at MPI-SusMat, investigated how the internal structure of 3D-printed copper influences its strength and deformation behaviour. Using localised electrodeposition, he produced microscopic copper tensile samples with different grain sizes, ranging from approximately 1.2 micrometres to just 40 nanometres. He then stretched these samples at different speeds to analyse how their mechanical properties change.

The experiments revealed that copper with very small grains shows higher strength, but fractures after less deformation and is more sensitive to the speed of loading. In contrast, copper with larger grains showed a weaker dependence on deformation speed and deformed through a different mechanism. Samples combining small and large grains exhibited intermediate behaviour, largely influenced by their nanocrystalline core.

These findings demonstrate how controlling the internal structure of 3D-printed metals can help tailor their mechanical properties. This could pave the way for metallic microstructures with layer-by-layer geometrical and microstructural tuning that combine high strength and stiffness with the ability to deform without breaking.

 

How hydrogen changes the deformation of steel at the microscale

2nd place: Kaili Feng

Hydrogen plays an important role in the transition towards sustainable energy. However, it can also affect the mechanical properties of metals, potentially making structural components brittle and more prone to damage. Understanding these effects is particularly important for metals used in hydrogen-related technologies.

Dr Kaili Feng, postdoctoral researcher at MPI-SusMat, investigates how hydrogen influences the local deformation of pearlite, a microstructural constituent that contributes to the strength of many engineering steels. Pearlite consists of alternating layers of relatively soft ferrite and hard cementite. The interfaces between these layers play an important role in how the material responds to mechanical stress.

Using microscratch testing, which involves dragging a tiny probe across a material's surface under controlled loading, Feng examined how pearlite deforms under a combination of compressive and shear forces. The experiments showed that hydrogen significantly increases the depth of scratch penetration and alters how deformation is accommodated within ferrite, cementite, and at their interfaces.

The findings provide new insights into how hydrogen interacts with the internal structure of steel. They could contribute to a better understanding of the early stages of hydrogen-induced damage in engineering steels, contributing to the development of more reliable materials for hydrogen applications.

 

Understanding fracture in liquid-encapsulated copper microspheres

2nd place: Jeongin Paeng

Advances in 3D printing allow researchers to create microscopic metal structures that contain liquids, opening up new possibilities for miniature sensors and medical drug delivery. However, the enclosed liquid also changes how these structures respond to mechanical forces, making their deformation and fracture behaviour more difficult to predict.

Jeongin Paeng, postdoctoral researcher at MPI-SusMat, investigated how liquid-filled copper microspheres behave under mechanical stress. Using localised electrodeposition, Paeng fabricated tiny hollow copper spheres containing approximately ten picolitres of liquid. To understand how cracks develop, the researcher introduced precisely controlled notches into the inner walls of the spheres and compressed them while observing their deformation. Computer simulations complemented the experiments.

The results revealed that the enclosed liquid plays a crucial role in determining when and where the copper shell fractures. As the liquid is difficult to compress, it generates additional pressure inside the sphere, increasing local stresses around the notches. Longer notches caused the microspheres to fracture at substantially lower levels of deformation. The study also examines how deformation speed and low temperatures, at which the enclosed liquid freezes, influence fracture behaviour.

These findings provide new insights into how liquids and solids enclosed within microscopic metal structures affect their mechanical reliability. Understanding these interactions could help researchers design more robust multifunctional microdevices, including miniature sensors that detect mechanical failure.

Understanding mechanical behaviour at the nanoscale

The ECI Nanomechanical Testing in Materials Research and Development X conference brings together researchers working on experimental techniques and scientific approaches to investigate the mechanical behaviour of materials at very small scales. Nanomechanical testing allows scientists to examine how individual microstructural features, interfaces and miniature components respond to applied forces – insights that are often difficult to obtain through conventional mechanical tests.

The four award-winning posters address different materials and applications, but share a common objective: understanding how a material's internal structure and local conditions determine its mechanical performance. Such insights are essential for designing stronger, more reliable and more resource-efficient materials and components for future technologies.