Nano Materials

Project Description

Building materials from bottom-up approach offers a wide range of tailoring opportunities. In this project we developed and characterized new class of materials with applications in magnetism. We used inert gas condensation technique to develop a new class of composite materials containing nanocrystals in a nanoglass matrix. We also developed cluster ion beam depositions to produce metastable structures.

Related Publications

• "A New Class of Cluster–Matrix Nanocomposite Made of Fully Miscible Components" - Advanced Materials Mar 2023. View Publication
  This study presents the creation of nanocomposite materials from a bimetallic system of nickel and copper, which are usually completely miscible under equilibrium conditions, using a novel cluster ion beam deposition system. The retention of the nanocomposite's metastable structure was confirmed through atom probe tomography, which showed nanoscale regions of nearly pure nickel, and the material's superparamagnetic behavior and magnetoresistance were identified via magnetometry and magnetotransport studies. These findings demonstrate that magnetic properties of nanocomposites can be finely tuned by controlling the nickel concentration, opening new avenues for research on nanocomposites made from fully miscible elements.
• "Energetically deposited cluster assembly of metallic glasses" - Acta Materialia July. 2022. View Publication
  Metallic glasses, traditionally created by rapid quenching and ball milling, lack a clear understanding of their structure compared to crystalline materials. Recent advances show that assembling amorphous nanoclusters via energetic deposition offers an alternative synthesis route for amorphous films, with local atomic structures differing from their rapidly quenched counterparts. A molecular dynamics study of Cu-Zr cluster-assembled metallic glass films has identified two distinct amorphous phases, one within the nanocluster cores and the other in the cluster interfaces, with each exhibiting unique chemical compositions and degrees of short-range order that can be tailored by adjusting the deposition energy.
• "Dislocation exhaustion and ultra-hardening of nanograined metals by phase transformation at grain boundaries" - Nature Communications Sept. 2022. View Publication
  This study discusses overcoming the challenges in the continuous grain refinement of high-strength metals, which is complicated by the inverse Hall-Petch effect. It demonstrates that nanograined metals (NMs) with grain sizes in the tens of nanometers can achieve strength comparable to or greater than ultra-fine-grained metals due to dislocation exhaustion. The research introduces a designed Fe-Ni NM with intergranular Ni enrichment that initiates structural transformations at grain boundaries at low temperatures, significantly consuming lattice dislocations. This leads to an ultra-hardening effect through the activation of grain boundary dislocation sources, proposing a novel approach for developing NMs with desirable properties by managing phase transformations through grain boundary physico-chemical engineering.
• "Nanoglass–Nanocrystal Composite—a Novel Material Class for Enhanced Strength–Plasticity Synergy" - Small Feb. 2018. View Publication
  The study introduces a new class of materials known as nanoglasses, which consist of nanosized glassy particles separated by amorphous interfaces, and possess notable properties. By optimizing the composition, specifically in the synthesis of a metastable Fe-10 at% Sc nanoglass, researchers achieved a hierarchical microstructure with a Fe90Sc10 amorphous matrix, hydrogen-stabilized amorphous interfaces, and self-assembled pure-Fe nanocrystals within the matrix. This innovative structure results in a material that combines high yield strength, exceeding 2.5 GPa, with remarkable plasticity, offering a new approach to designing materials with advanced properties.