MSE Seminar Series: Mostafa Hassani (Cornell)


Kimball Hall B11


High-Rate Mechanics and Manufacturing with Microparticle Impact

The combination of high pressures, temperatures, and deformation rates that occur during a microparticle impact can evoke many interesting material responses, ranging from solid-state bonding to extreme deformation and failure mechanisms. In this talk, we provide an overview of three ongoing projects in our group focusing on microparticle impact. First, we discuss the micromechanics of impact-induced bonded interfaces in metals. We present in-situ impact experiments and site-specific micromechanical measurements to develop process-microstructure-property relationships for such interfaces. We report a gradient of interfacial strength and discuss it in light of the nanoscale interfacial features. Second, we focus on deformation mechanisms in metals under high strain rates, where increasing deformation rates lead to a shift from thermally activated motion of dislocations to their interactions with phonons, ultimately resulting in embrittlement. We present an impression-based approach to quantify the dislocation-phonon drag regime and discuss microstructural strategies to suppress it at high strain rates. Finally, we demonstrate that using impact-induced bonding with the cold spray process, we can additively manufacture metal-ceramic composites. We use synchrotron X-ray diffraction and X-ray microtomography to resolve the microstructure and the phase-specific response of the composites under uniaxial loading. We highlight the role of defects arising from impact-induced fracture of ceramic particles and discuss potential strategies to alleviate them.

Mostafa Hassani is an Assistant Professor jointly within the Sibley School of Mechanical & Aerospace Engineering (MAE) and the Department of Materials Science and Engineering (MSE) at Cornell. Prior to that, he completed a Senior Research Associate and Lecturer appointment at Cornell, a Post-doctoral appointment at MIT, and a Ph.D. degree at Politecnico di Milano.