Research Highlights: Behnam Amin-Ahmadi
Behnam’s research is focused mainly on the development and engineering of new biomedical shape memory alloys for additive manufacturing (3D printing) production. Conventional NiTi shape memory alloys need prior cold work to achieve the proper superelastic behavior. New NiTiHf alloys, by contrast, reach high strength and good superelasticity through the formation of so-called “H-phase” precipitates without initial cold working. These alloys can therefore be good candidates for the 3D printing of shape memory alloys. The first part of Behnam's project applies different chemical compositions and heat treatments to achieve proper mechanical properties and martensitic transformation temperatures. The microstructure of these alloys is investigated in detail using advanced microscopy techniques, such as scanning electron microscopy (SEM), focused ion beam (FIB), electron backscatter diffraction SEM (EBSD-SEM), high-resolution transmission electron microscopy (TEM), scanning TEM, and STEM-EDX, among others. These fundamental studies can reveal the responsible mechanisms affecting transformation temperature, superelasticity, and plastic deformation in these alloys. The second part of the project focuses on optimizing processing parameters for additive manufacturing of NiTiHf and characterizing 3D-printed parts in detail.