Crystal structure and electrical resistance of Ni-W alloys

Abstract

The purpose of the paper is to establish the correlation between chemical composition, phase content and magnetic ordering of Ni₍₁₋x₎Wx alloys and behavior of their electronic properties in a wide range of temperatures. Alloys Ni₍₁₋x₎Wx of different composition (0 < x < 0.5) are synthesized. It is studied the crystal structure and the nature of the temperature dependence of electrical resistivity. It is shown, that in the range of concentrations of tungsten 0 < x < ~0.15 there is only face centered cubic (FCC) lattice, whereas, at the higher values of x, the Ni-W alloy is two-phase system consisting of the face centered and body centered cubic (BCC) crystal structures. The strong drop in residual resistivity ratio (RRR) with increasing of x in the ferromagnetic area of single-phase FCC alloy, the weak dependence of RRR in the paramagnetic area of the FCC alloy, and growth of RRR in the two-phase region (FCC + BCC) of Ni-W are observed. It is established, that in the two-phase region of the alloy at concentrations of ~0.15 < x < 0.3 the electric current flows through the matrix of FCC Ni-W. At the higher concentrations of tungsten (x≥~0.3) the mechanism of charge transfer changes: electric current flows through percolation channels, formed by BCC phase of Ni-W system.