Nanomolding of Metals Far and Close to Equilibrium

Speaker: 
Naijia Liu
Seminar Date: 
Friday, December 6, 2019 - 12:00pm
Location: 
Mann Student Center - Room 107 See map
10 Hillhouse Av
New Haven, CT

Significant effort has been taken during the last two decades in the development of nano fabrication techniques for metals. A wide range of bottom-up and top-down techniques have been developed. Those techniques, however are generally limited in some critical aspects such as material choice, geometry, and/or scalability.As another highly versatile method, nanomolding has been realized for soft materials that soften at elevated temperatures, but not for crystalline metals. Recently, we discovered that nanomolding is possible with crystalline metals. Scaling considerations suggest that the underlying process is based on atomic diffusion following applied pressure gradient. Most effective at ~0.5 TM such thermomechanical nanomolding (TMNM of crystalline metals) results in very high aspect ratio of up to ~1000 and nanowires as small as 5 nm in diameter. As the underlying diffusion process is   in all metals and alloys, TMNM offers itself as a versatile nanomolding technique. We will compare the underlying mechanism during nanomolding of metallic glasses and that of crystalline metals. In the case of TMNM of crystalline metals, formation of single crystals and typically tight adherence to the equilibrium state is the general outcome whereas during thermoplastic nanomolding of metallic glasses the formed nanorods remains far away from equilibrium.

Host: 
Corey O'Hern