Multi-component low and high entropy metallic coatings synthesized by pulsed magnetron sputtering

This paper presents the findings of the synthesis of multicomponent (Al, W, Ni, Ti, Nb) alloy coatings from mosaic targets. For the study, a pulsed magnetron sputtering method was employed under different plasma generation conditions: modulation frequency (10 Hz and 1000 Hz), and power (600 W and 1000 W). The processes achieved two types of alloy coatings, high entropy and classical alloys. After the deposition processes, scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy techniques were employed to find the morphology, thickness, and chemical and phase compositions of the coatings. Nanohardness and its related parameters, namely H3.Er2, H.E, and 1.Er2H ratios, were measured. An annealing treatment was performed to estimate the stability range for the selected coatings. The results indicated the formation of as-deposited coatings exhibiting an amorphous structure as a single-phase solid solution. The process parameters had an influence on the resulting morphology-a dense and homogenous as well as a columnar morphology, was obtained. The study compared the properties of high-entropy alloy (HEA) coatings and classical alloy coatings concerning their structure and chemical and phase composition. It was found that the change of frequency modulation and the post-annealing process contributed to the increase in the hardness of the material in the case of HEA coatings

The role of magnetic energy on plasma localization during the glow discharge under reduced pressure

In this work, we present the first results of our research on the synergy of fields, electric and magnetic, in the initiation and development of glow discharge under reduced pressure. In the two-electrode system under reduced pressure, the breakdown voltage characterizes a minimum energy input of the electric field to initiate and sustain the glow discharge. The glow discharge enhanced by the magnetic field applied just above the surface of the cathode influences the breakdown voltage decreasing its value. The idea of the experiment was to verify whether the contribution of potential energy of the magnetic field applied around the cathode is sufficiently effective to locate the plasma of glow discharge to the grounded cathode, which, in fact, is the part of a vacuum chamber wall (the anode is positively biased in this case). In our studies, we used the grounded magnetron unit with positively biased anode in order to achieve favorable conditions for the deposition of thin films on fibrous substrates such as fabrics for metallization, assuming that locally applied magnetic field can effectively locate plasma. The results of our studies (Paschen curve with the participation of the magnetic field) seem to confirm the validity of the research assumption. What is the most spectacular - the glow discharge was initiated between introduced into the chamber anode and the grounded cathode of magnetron ‘assisted’ by the magnetic field (discharge did not include the area of the anode, which is a part of the magnetron construction)

Dependence of the specific features of two PAPVD methods: Impulse Plasma Deposition (IPD) and Pulsed Magnetron Sputtering (PMS) on the structure of Fe–Cu alloy layers

This paper describes the study of the structural properties of the alloy layers prepared by two different, impulsively working PAPVD methods: the Pulsed Magnetron Sputtering (PMS) and the Impulse Plasma Deposition (IPD). The Fe–Cu alloy layers were synthesized. The results of our investigation revealed a nanocrystalline structure of the layers. The differences in the phase composition of the Fe–Cu alloy layers produced by these two methods were observed. The synthesis of the Fe–Cu layers by using the Pulsed Magnetron Sputtering method resulted in obtaining the two-phase, polycrystalline structures (fcc-Cu and bcc-Fe). In this case the clear evidence of mixing between the iron and copper atoms was not observed. The Fe–Cu layers deposited by the Impulse Plasma Deposition method were characterized by the non-equilibrium phase composition – the presence of one-phase supersaturated solid solution (fcc-Cu(Fe) or bcc-Fe(Cu)) was formed in immiscible systems. These results suggest a short-distance diffusion between the neighboring nanoparticles of the two metals (Cu and Fe) occurring during the IPD layers growth

Carbon ion self-sputtering attained by sublimation of hot graphite target and controlled by pulse injection of a neon-helium gas mixture

The operation of graphite targets with an increased temperature (HT - hot target) is studied for the case of gas injection magnetron sputtering (GIMS) of: 1) diamond-like carbon (DLC), and 2) carbon-silicon carbide (C-SiC) films. A purposely-thinned graphite target with a reduced thermal conductivity is applied for DLC deposition, extending its high temperature sputtering range up to 1636 degrees C. For the purpose of C-SiC synthesis four sockets with a silicon carbide powder are designed within graphite target. In this approach, the C-SiC target surface can be heated up to 1443 degrees C due to a greater energy input from impulse plasma, in the range 322-932 J. The HT sputtering is energy-controlled by a pulsed injection of a neon-helium gas mixture. High-energy Ne+ and He+ ions extend the length of pulsed GIMS discharge due to the self-sputtering effect observed during the deposition of DLC and C-SiC films. These conditions result in an almost 5-fold increase in the film growth rate (up to 185 nm/min) with respect to the operation with a cold target, which is due to the assisting vapour sublimation from custom-designed graphite-based targets. The temperature boosted HT GIMS discharge, proves to be an efficient tool for reaching relatively high (similar to 35 %) sp(3)-hybridized C content in both carbon-based materials. It also allows for tailoring the energy bandgap of DLC-based optical structure, in the range from 1.7 to 2.75 eV, due to the formation of the (C-C) and (C-O) bonds. Higher content of silicon oxide (SiO2-x) and silicon carbide (SiC) phases (15 - 23 %) in the case of C-SiC films results in hardness increase from 21.8 to 30.1 GPa.Funding Agencies|National Science Centre of Poland [2018/31/B/ST8/00635]; National Science Centre of Poland under PRELUDIUM project [2017/27/N/ST8/00454]; Warsaw University of Technology within the Excellence Initiative: Research University [1820/151/Z09/2021]; Swedish Research Council VR [2018-03957]; Swedish Energy Agency [51201-1]</p