Resumen y bibiografía:
High-entropy alloys (HEAs) are multi-principal elements materials that challenge the traditional alloy design techniques. Due to their large design space and ample mechanical, optical, electrical, and thermal properties, HEAs are exiting material systems to explore and replace some of the high-strength materials available such as steel. HEAs are gaining momentum in the materials science and mechanics communities as they open up new research opportunities. However, besides having larger lattice friction values than conventional metals, HEAs perform at significantly lower levels than most high-strength materials available. Thus, researchers explore novel compositions -including multi-phase HEAs- and manufacturing techniques to develop intricate microstructures. Computational frameworks open up the possibility of exploring these design spaces and manufacturing methods and can be combined with experimental approaches to reduce the time and cost of novel HEAs discovery. In this presentation, using ab-initio simulations and experiments, I will explore the design space of non-equiatomic CoCrFeNi and CoCrFeMnNi HEAs with additions of Mo and Nb. Remarkably, it is shown that the simultaneous combination of these two solute atoms leads to alloys with optimal electronegativity, reducing the size of the precipitates while providing solid-solution hardening. Further, these atomic-scale fingerprints can be combined with additive manufacturing processes to develop rich microstructures. In particular, it is experimentally and numerically shown how feedstock HEAs particles can dynamically recrystallize during cold-spraying additive manufacturing to create nano-sized grains. Lattice orientation and particle shape effects on DRX are shown, and they can be tailored to produce gradient nano-grained structures. We explore the mechanical and microstructural features of a CrFe0.75CoNiNb0.125Mo0.3 cold-sprayed, which shows remarkable mechanical properties surpassing most face-centered cubic HEAs and most high-strength steels.
Bio:
Mauricio Ponga es actualmente Profesor Asistente en el Departamento de Ingeniería Mecánica de la Universidad de British Columbia. Antes de UBC, el Dr. Ponga fue becario postdoctoral en el Departamento de Ingeniería Mecánica y Civil del Instituto de Tecnología de California bajo la supervisión del Prof. Kaushik Bhattacharya y el Prof. Michael Ortiz. El Dr. Ponga se graduó con un Ph.D. y M.Sc. por la Universidad de Sevilla (2013, 2010) y Licenciado en Aeronáutica por la Universidad de La Plata (2007). Los intereses de investigación del Dr. Ponga se centran en el desarrollo de nuevas técnicas de simulación de modelado para comprender los materiales a nanoescala, incluidas, entre otras, simulaciones ab-initio a gran escala, simulaciones de dinámica molecular clásica y acelerada y dinámica de dislocación. Más recientemente, Ponga se ha centrado en el diseño computacional y experimental combinado de aleaciones de alta entropía para ultra resistencia y tenacidad.
