Resistivity and its temperature dependence of nanostructured NiAl at temperatures from 77 to 300 K

Direct current resistivity and its temperature dependence for nanostructured NiAl (n‐NiAl) was investigated at temperatures from 77 to 300 K. The resistivity of n‐NiAl (size 5–6 nm) was higher than that of polycrystalline NiAl and increased with decreasing density. For the n‐NiAl with relative density D≳70%, the resistivity decreased with decreasing temperature, manifesting metallic behavior. However, its temperature coefficient of resistivity decreased monotonically with decreasing density, and changed sign from positive to negative at densities 68%–70%, below which it displays on nonmetallic behavior. These results can be well interpreted by dominant grain boundary scattering.