A team of researchers from IMDEA Materials Institute and the Carlos III University of Madrid (UC3M), working with collaborators in France and Japan, has published a study in the Journal of the Mechanics and Physics of Solids that details how microscopic defects in additively manufactured metals behave under extreme dynamic loading.

The study focused on AlSi10Mg and Ti-6Al-4V, two alloys widely used in Laser Powder Bed Fusion (LPBF), which are susceptible to microscopic pores in the finished part and replicated conditions directly relevant to aerospace, transport and defense components.

Experiments were conducted at the European Synchrotron Radiation Facility (ESRF) in France, where specimens were struck at velocities of up to 750 meters per second while ultrafast X-ray phase-contrast imaging, operating at nanosecond time resolution, recorded the internal response.

The results were highly intriguing. Imaging captured a consistent failure sequence across both alloys: an initial shock wave caused pores to collapse, followed by pore reopening and growth as stress waves induced tension, ultimately driving the voids to link together and produce what is known as spall fracture — an internal crack that forms away from the surface and is therefore harder to detect than conventional surface-initiated failures.

From pore scale to macroscopic failure

“This approach allows us to directly observe how damage forms and evolves inside additively manufactured metals during extreme loading,” said Dr. Federico Sket, Senior Researcher at IMDEA Materials Institute.

Prof. José A. Rodríguez Martínez, Professor at UC3M and Visiting Scientist at IMDEA Materials, stated that “for the first time, we can connect what happens at the microscopic scale with the macroscopic signals measured during impact experiments.”

Although AlSi10Mg and Ti-6Al-4V displayed differences in fracture morphology, both alloys were governed by the same underlying void growth and coalescence mechanism.

Dr. Javier García Molleja, Researcher at IMDEA Materials, stated: “Altogether, this paper provides new insights into dynamic tensile fracture of 3D printed metals. It does so by leveraging the latest advances in fast X-ray phase-contrast imaging and high-resolution tomography, while establishing a systematic protocol to investigate void collapse and spall failure mechanisms in porous materials subjected to shock loading.”

The research team — which also included contributions from the ESRF-European Synchrotron, the Max von Laue-Paul Langevin Institute in France, and the Japan Synchrotron Radiation Research Institute (JASRI) — proposed that the experimental framework be extended to additional aluminum and titanium alloy grades used in additive manufacturing, as well as to lightweight printed metals such as magnesium.