Fabrication, Corrosion, and Mechanical Properties of Magnetron Sputtered Cu–Zr–Al Metallic Glass Thin Film

The appearance of thin film metallic glasses (TFMGs) is gaining increasing interest because of their unique mechanical and anticorrosion properties and potential engineering applications. In this study, Cu–Zr–Al ternary thin film metallic glasses were fabricated by using DC magnetron sputtering equipment with various target powers. The evolution of the structure was systematically investigated by grazing incidence X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy. The deposition rate increases with the increasing of applied target power. The as-deposited thin films show an amorphous structure. The compositional fluctuations on the nanometer scale indicate the presence of two Cu- and Zr-rich amorphous phases. The electrochemical corrosion measurements indicated that Cu–Zr–Al thin film metallic glasses had good corrosion resistance in the sulfuric acid solution. Nanoindentation results showed that the mechanical deformation was found to be homogenous and reproducible with a high value range for the hardness and modulus

Effect of the Sputtering Power on the Structure, Morphology and Magnetic Properties of Fe Films

In this paper, the radio frequency (RF) magnetron sputtering (MS) method was utilized to fabricate multiple sets of the iron film samples under different sputtering powers. With the help of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM), how the sputtering power affected the structure, morphology and magnetic properties of the iron film was studied. XRD results showed that all Fe films have a polycrystalline bcc structure and (110) preferred orientation. According to the Bragg equation calculation, the larger the sputtering power, the larger the average grain size, which is consistent with the results of AFM particle size analysis. The main reason is that the sputtering power affects the grain growth mode. As the sputtering power increases, it gradually changes from a small island-like growth to a thick columnar growth. However, from the surface morphology and height profile, we saw that the iron film deposited under 230 W had the most uniform grain size distribution and the grain size was relatively small. This is why thin films deposited under this condition have the best soft magnetic properties. The saturation magnetization (Ms) reaches 1566 emu/cm3, coercivity (Hc) is 112 Oe, and squareness ratio (Mr/Ms) is 0.40. Therefore, iron film prepared under 230 W has good comprehensive properties (highest Ms, lower Hc and Mr/Ms) that provide an experimental basis for further thin film research work

Investigating the Wear Behavior of Fe-Based Amorphous Coatings under Nanoscratch Tests

The wear behavior of two coatings (Fe49.7Cr18Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 and Fe40Cr23Mo14C15B6Y2) sprayed by high-velocity air fuel technology was investigated through nanoscratch tests under ramping loads. Compared with the substrate, the Fe-based amorphous coatings exhibit lower penetration depth, higher elastic recovery, and lower wear volume, indicating the excellent wear resistance of the coatings. This behavior is related to the high hardness and high hardness/elastic modulus ratio (H/E) of the Fe-based amorphous coatings. From the scanning electron microscopy images of the scratch grooves, it is found out that ploughing governs the wear behavior of the coatings and substrate. In addition, spalling wear easily occurs in the pore regions of the coatings

Effect of deposition parameters on microstructure of the Ti-Mg immiscible alloy thin film deposited by multi-arc ion plating

Ti-Mg immiscible alloy thin films were prepared using a multi-arc ion plating technique with various deposition parameters. The surface and cross-section morphologies, crystal structures, and chemical compositions of the Ti-Mg films were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The influence of the substrate negative bias voltage and Ar gas pressure on the microstructure of the Ti-Mg films was systematically studied. Mg atoms were incorporated into the Ti lattice to form an FCC immiscible supersaturated solid solution phase in the thin film. Microparticles were observed on the film surface, and the number of microparticles could be significantly reduced by decreasing the substrate bias voltage and increasing the Ar gas pressure. The appropriate substrate bias voltage and Ar gas pressure increased the deposition rate. The TEM results indicated that columnar, nanolayer, and equiaxed nanocrystals were present in the thin films. Ti and Mg fluctuations were still evident in the nanoscale structures

MECHANICAL PROPERTY OF A NEW Zr-BASED BULK METALLIC GLASS WITH CERTAIN PLASTICITY AT LOW TEMPERATURE

The mechanical property of a new bulk metallic glass Zr CuNiAl, which owns 5% room-temperature plasticity, is investigated at low temperatures 193K and 123K. It is indicated that the yield strength and the plasticity significantly increase by 12.8% and 50% respectively as testing temperature is lowered from 298K (at room temperature) to 123K (in liquid nitrogen). The dense and multiple shear bands which contribute to the improved ductility are observed on the side surface of these samples fractured at low-temperature. Detailed study of the stress-strain curves for the samples deformed at low temperature show that more serrations and smaller stress drop form due to generation of more much shear bands

High Bending Strength Hypereutectic Al-22Si-0.2Fe-0.1Cu-Re Alloy Fabricated by Selective Laser Melting

The objective of the study is to investigate the corresponding microstructure and mechanical properties, especially bending strength, of the hypereutectic Al-Si alloy processed by selective laser melting (SLM). Almost dense Al-22Si-0.2Fe-0.1Cu-Re alloy is fabricated from a novel type of powder materials with optimized processing parameters. Phase analysis of such Al-22Si-0.2Fe-0.1Cu-Re alloy shows that the solubility of Si in Al matrix increases significantly. The fine microstructure can be observed, divided into three zones: fine zones, coarse zones, and heat-affected zones (HAZs). Fine zones are directly generated from the liquid phase with the characteristic of petaloid structures and bulk Al-Si eutectic. Due to the fine microstructure induced by the rapid cooling rate of SLM, the primary silicon presents a minimum average size of ~0.5 μm in fine zones, significantly smaller than that in the conventional produced hypereutectic samples. Moreover, the maximum value of Vickers hardness reaches ~170 HV0.2, and bending strength increases to 687.70 MPa for the as-built Al-22Si-0.2Fe-0.1Cu-Re alloys parts, which is much higher than that of cast counterparts. The formation mechanism of this fine microstructure and the enhancement reasons of bending strength are also discussed

Surface Post-Treatment Induced by Nanosecond Pulsed Laser Processing of HVAF-Sprayed Fe-Based Metallic Glass Coating

The effects of nanosecond pulsed laser processing (NPLP) on the surface morphology, microstructure, and corrosion resistance properties of Fe-based metallic glass coating were investigated. It was found that after pulsed laser processing, the metallic glass coating retained its amorphous structure; however, cracks were generated on the top of the coating. The thickness of the remelted zone reached about 30 μm, and the microstructure became denser after the remelting process. In addition, most of the original defects in the coating disappeared. The corrosion resistance of Fe-based metallic glass coating after NPLP was increased in 3.5 wt.% NaCl solution

Interface boosted highly efficient selective photooxidation in Bi3O4Br/Bi2O3 heterojunctions

Selective photooxidation of amines to biologically important imines is in great demand for industrial applications. The conversion efficiency and selectivity of the process are strongly dependent on the activation of photocatalytic molecular oxygen (O2) into reactive oxygen species. Here, we propose the construction of rich interfaces to boost photocatalytic O2 activation by facilitating the transfer of photocarriers. Taking Bi3O4Br/Bi2O3 heterojunctions as an example, rich interfaces facilitate electron transfer to adsorbed O2 for superoxide (O2·−) generation, thus achieving ≥ 98% conversion efficiency and selectivity for benzylamine and benzylamine derivatives. This study offers a valid method to design advanced photocatalysts for selective oxidation reactions

Investigation on pitting corrosion mechanism of the Fe-based amorphous alloy coating by three-dimensional X-ray imaging at micro-scale

Few work have been performed regarding the quantitative characterization of three-dimensional (3D) pitting corrosion process directly, although the corrosion behaviors and the passivation film stability of metals in various solutions have been studied heavily. The reported work quantitatively characterized the 3D pitting corrosion of the Fe-based amorphous alloy coating (Fe-based AAC) via X-ray micro-computed tomography (X-ray micro-CT) and further elucidated the mechanism of its pitting corrosion. Moreover, the microstructure and electrochemical performance of the Fe-based AAC have also been explored. The results showed that the targeted thermal sprayed Fe43Cr20Mo10W4C15B6Y2 coating was prone to be corroded with the increase of the hydrogen ion concentration, i.e. higher hydrogen ion concentration leads to poorer corrosion performance of the Fe-based AAC. The X-ray micro-CT results revealed that the pits in the Fe-based AAC initially nucleated below the pitting potential, and they also generated in the over-passivation stage. Furthermore, it was found that the corrosive medium does not penetrate into the coating/substrate interface, and the deduced corrosion mechanism from the findings was also discussed