THE PROPERTIES OF Cr–Co–Cu–Fe–Ni ALLOY FILMS DEPOSITED BY MAGNETRON SPUTTERING

Abstract

In spite of great efforts undertaken to produce and examine the properties of a new class of high-entropy alloys (bulk or film alloys), the existing information is still insufficient for creating scientific ideas that would connect the properties and process parameters of these alloys. We studied the dependence of the composition and structure of Co–Cr–Cu–Fe–Ni films deposited by magnetron sputtering on the physical parameter such as energy flux delivered to the growing film surface. This parameter is directly related to process parameters such as magnetron discharge current (I_d) and substrate bias voltage (U_b). The films have a nanocrystalline microstructure and crystallize as a two-phase fcc and bcc solid solution with the following lattice parameters: a = 0.363 nm for the fcc phase and а = 0.294 nm for the bcc phase. Ion bombardment of the growing film induced by bias voltage U_b varying from 0 to –300 V in the substrate influences the film structure and composition. Thus, the films deposited at ~300 V are noticeably depleted in copper, while the composition of the films deposited without ion bombardment is the same as that of the target. Greater energy flux delivered to the growth surface (higher Id and/or U_b in the substrate) increases the growth surface temperature, leading to grain coarsening and film texturing. The volume of the bcc phase also substantially decreases, until it disappears in the films deposited at U_b= –300 V. The films formed by the bombardment of ions with energy 100 eV showed the maximum (~19 GPa) microhardness.