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

Abstract
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.