|MIT Department: Materials Science and Engineering
Faculty Mentor: Prof. Christopher Schuh
Undergraduate Institution: University of California, San Diego
I am an upcoming senior at UC San Diego majoring in Nanoengineering with a specialization in materials science and engineering. My family is originally from Honduras, but I was born and raised in the California Bay Area. My research experience encompasses various aspects of ceramics science and metallurgy, focusing on the fabrication of bulk ceramics and ceramic microstructures for high hardness and ultra-high temperature resistant applications in body armor and aircraft. My research interests lie within the field of bioinspiration, where I am interested in taking design motifs and structures found within biological materials in nature (spider silk, horse hooves, seashells) and replicating these hierarchical structures within engineering materials such as ceramics, metals, polymers, and inorganic materials. Furthermore, I am also interested in the use of bioinspired materials for biomedical applications such as prosthetics, implants, and tissue regeneration. As such, I am incredibly enthusiastic about fields such as additive manufacturing, sintering, and photopolymerization. My future goals are to work for the Department of Defense or DARPA and use my research for defense applications and biomedical technologies. I am also a filmmaker on the side, with dreams of making action / sci-fi films, I enjoy acting and theater, and I am an avid lover of classical piano music. I also thoroughly enjoy health and fitness, and hope to learn more about parkour, gymnastics, and bodybuilding.
Refractory Metal Nanocrystalline Alloys using Nanophase Separation Sintering
Samuel David Figueroa1, Christian Edward Oliver2, Yannick Naunheim2, Christopher Schuh2
1University of California, San Diego, La Jolla, CA 92093, United States
2Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
Nanocrystalline alloys have gained a great deal of interest amongst both the scientific community and the metallurgy industry due to their exceptional physical properties, owing to their very fine microstructures. However, sintering of metallic powders to fully dense nanocrystalline parts is a challenge due to the tendency for microstructural features to coarsen under rigorous thermal processing cycling. Low temperature processing accelerated sintering techniques are thus necessary for the realization of these materials, with conventional low temperature processing techniques such as liquid-phase sintering being incapable of achieving fine microstructures. Herein, we propose the use of a novel sintering technique using micron-sized tungsten (W) solvent powder particles with nanocrystalline grains supersaturated with a chromium (Cr) solute. This powder alloy system upon heating begins to phase separate to form a solute-rich phase with nanostructured necking between solvent powder particles to support rapid diffusion of atoms, resulting in sintering behavior at a low temperature ~950°C. Without applied pressure processing, W-15 at. % Cr binary alloy powders sintered to 1500°C already reach full density. Sample microstructures are imaged using optical and scanning electron microscopies, with results clearly demonstrating nanocrystalline features. Further work demonstrates that this technique can be used in other binary alloy systems, broadening the applications for production of other nanocrystalline materials.