(Zr,Ti,O) alloy films with enhanced hardness and resistance to cracking prepared by magnetron sputtering

Abstract

The article reports on the effect of (i) the ion bombardment and (ii) the addition of small amount of oxygen into Ar sputtering gas on the structure, microstructure, mechanical properties and macrostress of the (Zr,Ti) alloy films prepared by DC magnetron sputtering. Properties of the (Zr,Ti) alloy films with three different elemental compositions – (1) Zr95Ti5, (2) Zr30Ti70 and (3) Zr5Ti95 were investigated in detail. It was found that (1) the (Zr,Ti) alloy films sputtered at a low value of the negative substrate bias Us=−50V are well crystalline, (2) the (Zr,Ti) alloy films sputtered at high values of the negative substrate bias | Us |≥150V are nanocrystalline, (3) the (Zr,Ti) alloy films, sputtered at all substrate biases Us used in our experiments and ranging from −50 to −250V, exhibit low hardness H<10GPa, low ratio H/E⁎<0.1, low elastic recovery We<60% and low resistance to cracking and (4) the addition of small amount of oxygen in Ar sputtering gas makes it possible to sputter nanocrystalline (Zr,Ti,O) alloy films with high hardness H>10GPa, high ratio H/E⁎≥0.1, high elastic recovery We≥60% and enhanced resistance to cracking; here E⁎ is the effective Young's modulus. The main result of the presented investigation is the demonstration that the incorporation of a small amount of O in a (Zr,Ti) alloy film is a very effective way to increase its hardness and to form the flexible (Zr,Ti,O) alloy films with enhanced resistance to cracking.