Mg-based metal-matrix nanocomposites (MMNCs) are lauded as one of the most promising structural materials for vehicle, military, and construction applications. These Mg MMNCs are often synthesized using the powder metallurgy (PM) process under liquid nitrogen cryogenic environments to control the grain sizes. It is believed that proper incorporation of the nitrogen species into the bulk lattice during processing could strongly enhance the mechanical properties of MMNCs by forming N-rich dispersoids. In this work, using the density-functional theory (DFT), we have studied the adsorption and absorption phenomena of liquid nitrogen molecule/atoms that can be applied to the Mg MMNC PM processing. The study includes the impacts of binding sites, alloying elements (Al, Zn, and Y), and surface crystallographic planes on the nitrogen molecule adsorption energies. We also examined the transition state (TS) behaviors for the bond breaking and lattice diffusion of nitrogen. The results show that ∼1.13 eV would be required for nitrogen molecule to break the triple bonding and to diffuse into the Mg bulk lattice. Also, it was found that addition of Y can greatly enhance the binding strength of N2 molecule on the Mg surface.
Bibliographical noteFunding Information:
This material is based upon work supported by the U.S. Army Research Laboratory under Cooperative Agreement No. W911NF-08-2-0014. The views, opinions, and conclusions made in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein.
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All Science Journal Classification (ASJC) codes
- Computer Science(all)
- Materials Science(all)
- Mechanics of Materials
- Physics and Astronomy(all)
- Computational Mathematics