ESRF scientist Can Yıldırım receives ERC grant to study how metals crystallise

Metals are often subjected to a variety of treatment processes to modify their physical and mechanical properties. These processes, such as annealing, quenching, and tempering, can significantly affect the hardness, strength, and ductility of the metal.

"Our current knowledge of metals is still based on average properties, but to create better materials with enhanced performance, reduce weight while saving energy, we must comprehend the local structural changes," explains Can Yıldırım, a scientist at the new flagship EBS beamline ID03 and new recipient of an ERC starting grant.

One crucial local modification occurs through recrystallisation, a phenomenon commonly observed during metal processing. It is similar to a reset button for deformed metals, making them softer during annealing. Despite its importance, fundamental questions about recrystallisation remain unresolved, such as where the grains form or how they grow. "It's like trying to find a needle in a haystack," says Yıldırım. Existing methods for studying recrystallisation are either destructive or lack the spatial resolution to observe the critical details.

Yıldırım's project, entitled "Deformation and Recrystallization Mechanisms in Metals (D-REX)," aims to develop a groundbreaking technique for unraveling the 4D local structures and recrystallisation processes within metals. This information is essential for understanding the factors that control the strength of the metals. D-REX, which will start in 2024 and will last for five years, will bring to life the technique of pink beam Dark Field X-ray Microscopy (pDFXM) to significantly expedite imaging. pDFXM will empower researchers to examine metals under real-world conditions and investigate higher strain levels in situ. While Dark Field X-ray Microscopy has been effectively employed for studying metals, it faces two limitations: inadequate signal for mapping deformed crystals and a single-grain mapping approach that fails to capture surrounding information.

Yıldırım emphasizes the significance of the new EBS beamline: "The recently established ID03 beamline at ESRF is pivotal for my research; without it, this project simply would be unfeasible."

A central aspect of Yıldırım's approach involves enhancing DFXM imaging speed by employing pink beam technology instead of the conventional monochromatic beam. This upgrade is projected to accelerate DFXM imaging almost by a factor of 100, enabling in-situ studies and the exploration of materials experiencing even higher strain levels. Furthermore, integrating 3D X-ray diffraction (3DXRD) with DFXM facilitates the quantification of microstructures within a multiscale framework.

D-REX aims to address fundamental questions concerning how recrystallisation impacts local structures and predict initiation sites. The project promises real-time, comprehensive insights into deformation, annealing, dislocation structures, subgrain dynamics, and nucleation and growth processes. This endeavor will refine material models, shedding light on localised hotspots.

Once established, this innovative technique will pave the way for addressing various scientific challenges related to local structural changes in metals, including fatigue, phase transformations, and creep. Additionally, it will provide insights into other materials like battery longevity and in-vivo growth mechanisms in biominerals.

"Can Yıldırım is the second ESRF internal applicant to succeed in this highly competitive process, highlighting the attractiveness of ESRF for top young talents and the quality of our hiring processes," explains Gema Martínez-Criado, ESRF director of research for physical sciences.

Top image: Can Yıldırım at the ESRF. Credits: Jeff Wade.