Compression Strength of Ni-Fe Nanoparticles

In bulk metals, alloying with another component usually increases the strength of the alloy (solid solution strengthening). However, an experimental work conducted previously in our group showed that alloying the Ni nanoparticles with Fe decreases their strength. This is another indication of the fundamental difference between the plastic deformation of bulk metal samples and of the pristine defect-free metal nanoparticles. For better understanding of the underlying mechanisms of plastic deformation and failure of nanoparticles, we performed Molecular Dynamic (MD) computer simulations that closely mimic the experimental conditions. We have constructed a set of equilibrated particles exhibiting the Wulff shape with rounded edges. The compression of particles of the Ni-25 at %Fe (Ni₃Fe) composition in disordered state, and in the ordered L1₂ state was simulated. The compression of the particles of pure nickel was also simulated for the reference. The results of simulations confirm the solid solution weakening observed in the experiment. The obtained results are discussed in terms of the effect of solute atoms on dislocations nucleation.