Deposition and characterization of refractory ternary phases: the transition metal nitride Ti 1 − xMo xN y

Abstract

Differences in the number of valence electrons and atomic mass in the transition metals of ternary nitride phases cause relevant evolutions in the physical properties of these refractory coatings. This report presents results on structural and mechanical investigations in the Ti 1 − x Mo x N y system. Thin films are deposited by RF reactive magnetron sputtering from two metal targets. Different structures corresponding to a wide range of chemical compositions determined by electron probe microanalysis are obtained by varying the nitrogen partial pressure and the discharge powers. The crystallographic phase is analyzed by X-ray diffraction: for 0≤ x≤0.79 and 1.65≤y≤1.04 the samples are single phase face centered cubic. For 0.5≤ y≤0.65 the phase transition from γ-Mo 2N to face centered cubic occurs. The steepness of the transition is related to the titanium content. The microhardness H K is measured by Knoop indentation. For 0.06≤ y≤0.17 the microhardness is higher than for pure molybdenum. For y≈0.5 the highest values are reached for x=1. Increasing y, H K increases and reaches, for 0.40< x<1.00, a value 40% higher than sputter-deposited TiN. The correlation between the change in mechanical and structural properties is discussed within the ranges of x and y.