Lower Hardness Research Articles

Effect of enzymes on baking quality of wheat dough and storage quality of toast bread

SummaryToast is a nutrient‐rich consumer staple with a unique taste. However, retrogradation affects its storage quality and shelf life. Therefore, in this study, we aimed to investigate the effects of enzymes on the baking quality of wheat dough and the storage quality of baked bread. Fungal α‐amylase (FAM), lipase (LIP), and maltose amylase (MAM) were added to wheat dough under quadruple fermentation to evaluate their effects on the quality of wheat dough and toasted bread during storage. FAM reduced the water absorption and stability of wheat flour, whereas LIP and MAM improved its properties. Moreover, all three enzymes increased the fermentation height and gas‐holding capacity of the dough, resulting in toast with a larger specific volume and low hardness. Toast containing 15 mg kg−1 MAM had the highest number of air holes and the best elasticity. Furthermore, 9 mg kg−1 FAM, 45 mg kg−1 LIP, and 15 mg kg−1 MAM retarded the retrogradation of toast during storage, reduced its hardness, and decreased the short‐range order and relative crystallinity. These findings indicate that enzymes can delay retrogradation in toast to extend its shelf life. These results further suggest that enzymes inhibit recrystallisation to delay toast ageing. Thus, this study provides theoretical references for the practical application of enzymes in bakery products.

Characterization and structure-functionality analysis of starch in different layers of Lycoris chinensis bulb scales

According to literature, the size distribution of starch granules varies significantly in different layers of Lycoris chinensis bulb scales, however its effect on structural and physicochemical properties of starch still remains unclear. In this study, outer, middle and inner layers of bulb scales of L. chinensis were compared for starch characteristics. Also, the structure-functionality association was investigated based on correlation analysis and hierarchical cluster analysis, using 37 starch quality traits. Compared to commonly consumed starches with similar amylose content, L. chinensis starch gel had lower hardness and viscosities. Among layers, starches varied significantly in particle size, physicochemical and structural properties. As compared to middle and inner scales, the starch in outer scales had higher amylose content, hardness and viscosities, but lower gelatinization temperature, weight-average molar mass and degree of polymorphism. Correlation analysis revealed significant correlations among traits, and interestingly, gelatinization temperature (Tp) was found positively correlated to traits of molecular weight (p < 0.05). The 37 traits of starch characteristics can be divided into three subgroups, as supported by the results of Pearson correlation analysis and hierarchical cluster analysis. In general, the information presented in the current study are useful for Lycoris bulb starch utilization and insightful for a better understanding of structure-functionality association of starch.

Design of novel high entropy alloys based on the end-of-life recycling rate and element lifetime for cryogenic applications

The equiatomic face-centred cubic (FCC) CoNiCrFeMn alloy, known as the Cantor alloy, is renowned for its high ductility under extreme conditions, such as cryogenic temperatures. Despite this, it suffers from low hardness and yield strength (YS) and includes elements with significant supply concerns. This study introduces novel non-equiatomic CoNiCrFeMn alloys, designed using machine learning (ML)-assisted-high-throughput atomistic simulations to enhance sustainability and mechanical properties such as hardness and YS while maintaining the alloy's single-phase FCC structure. We incorporated two critical sustainability indicators, end-of-life recycling rate (EOL−RR) and lifetime (τ), to guide the alloy design process. Mean-flow stress (MFS), measured from the yield point to 15% strain during tensile tests, was used to assess and predict the mechanical properties. Two alloys, with cobalt contents of 12.5% and 21.5%, were developed and analysed. The Co12.5 alloy showed better sustainability (44% improvement in τ with almost the same mechanical properties), while the Co21.5 alloy exhibited better mechanical properties (20% improvement in MFS with almost the same sustainability) as the equiatomic system. Their stable FCC microstructures were confirmed through CALPHAD modelling and X-ray diffraction (XRD) analysis of vacuum arc melted, as-cast samples. The results highlight the potential of integrating sustainability metrics into high-performance alloy design.

Surface hardening of high modulus steels through carburizing and nitriding: First insights into microstructure property relationships

High modulus steels are promising materials for future lightweight design solutions, as their embedded boride particles in a ductile steel matrix increase the stiffness/density ratio. One key requirement for maturing them towards industrial application is their suitability for improving the surface hardness. In this study we investigated the effects of low-pressure carburizing and plasma nitriding on the microstructure and mechanical properties of selected Fe-TiB2- and Fe-Cr-M2B-based high modulus steels. Nitriding resulted with the formation of expanded ferrite in the strongest hardness increase to about 1100 HV0.05 from the alloy system's base hardness of 240 and 500 HV0.05, respectively, albeit with different hardness depth profiles. The Fe-Ti-B alloy indicated deformation phenomena in the ferritic matrix after nitriding, whereas nitriding of Fe-Cr-B-C resulted in a diffusion-controlled particle transformation of M2B borides into CrN nitrides of lower stiffness. Carburizing on the other hand led to a slightly lower maximum hardness value of about 800 HV0.05 over an increased depth for Fe-Cr-B, as martensite and additional M23C6 carbides were formed in the surface zone. The surface hardness of the Fe-TiB2-based alloy could not be increased by the deployed carburization parameters, most likely due to excessive Ti dissolved in the matrix. Consequences for the transfer to engineering applications as well as the refinement of both, thermochemical processing parameters and designated alloy concepts, of high modulus steels are outlined and discussed.

β-amino alcohols as promising inhibitory candidates against the SARS-CoV-2, A theoretical design based on MD simulation and DFT insights

Nelfinavir, as a compound with a Chiral β-amino alcohol unit, is a well-known inhibitor against HIV-protease, studying. The role of heterocyclic derivatives of Nelfinavir as inhibitors against the Main-Protease of COVID-19 is the main purpose of this study. To reach a deep understanding, different theoretical approaches including molecular docking, Molecular Dynamic (MD) simulations, and DFT insights are applied in the studies. Investigation of the ligand bioactivity reveals that smaller HOMO/LUMO band gaps and lower chemical hardness (η), mean stronger interaction with the active site of the Main-Protease for the corresponding β-amino alcohols. Analyzing the efficient interactions in binding energy shows that among the studied Chiral β-amino alcohols, formed Van der Waals interactions via π and alkyl parts of ligands have more remarkable roles in inhibitory effects than hydrogen bonding. Accordingly, molecular mechanics (MM) and polar interactions have the highest contributions to the total energy of residues. Finally, it has been concluded that among the studied derivatives those that contain Dihydroisoquinoline (4b), and Perhydroisoquinoline (4d) heterocyclic rings can be considered as more potent candidates against Main-Protease of COVID-19.

Effect of laser remelting treatment on the tribological properties of plasma sprayed WC–Cr3C2–Ni reinforced NiCrBSi coatings

The incorporation of single hard phases, such as tungsten carbide (WC), and chromium carbide (Cr3C2), into NiCrBSi coatings effectively enhances their performance, thereby fulfilling the tough requirements of high-temperature friction condition. To investigate the collaborative reinforcing effect of multiple hard phases and further enhance the high-temperature wear resistance of the coating, a novel WC–Cr3C2–NiCrBSi binary hard phase reinforced coating was developed and subjected to laser remelting treatment. The as-sprayed coatings demonstrate a distinct lamellar structure that diminishes upon remelting, resulting in significant densification of the coatings and a reduction in porosity to 0.3 %. The microhardness of the remelting coatings is reduced by about 10 % due to dilution of the coating by the lower hardness of the base material. However, during the laser remelting process, WC and Cr3C2 decompose and dissolve into the alloying binder phase of the coating, serving as solid solution agents. In cases where the concentration of W elements is elevated, a considerable precipitation of W-rich carbide is observed within the coating. Notably, N30 coatings demonstrate remarkable were resistance at both ambient and 700 °C, resulting in a significant reduction in wear volume by 86.5 % and 55.2 % respectively in comparison to original NiCrBSi coatings. The remelting treatment enhances the densification of the coating, improves the homogeneity of the microstructure, and reduces the coefficient of friction of the coating. The laser-remelted coating exhibits a decreased wear volume, attributed to a transition in its wear mechanism from fatigue-dominated to abrasive wear at room temperature. Conversely, under frictional conditions at 700 °C, the remelted coating experiences an augmented wear volume, attributed to severe abrasive wear.

Synthesis, performance and application of environmental protection scale inhibitorβ-CD-MA-SSS copolymer——in electric power industry

The issue of water scaling in the treatment of cooling water has become an imperative problem that should be solved urgently for the sake of safe operation in large-scale flexible DC converter stations. However, the coexistence of Ca2+ and Mg2+ in high content in this sort of pending raw water is quite hard to tackle. β-CD-MA-SSS, an eco-friendly ternary co-polymer antiscalant with good performance of inhibiting the formation of scale, was applied to address this conundrum in this paper. The efficacy of the antiscalant β-CD-MA-SSS was investigated in cooling water systems under the conditions of low hardness, low alkalinity, a temperature not exceeding 80 °C, and a pH range of 6–8. After optimization, this reagent dem onstrated an excellent scale inhibition rate up to 80% for both calcium carbonate and calcium-magnesium mixed scales. Scanning electron microscopy (SEM) analysis revealed a noticeable reduction in the size of CaCO3 particles when subjected to the action of β-CD-MA-SSS. It was postulated from FTIR analysis that nanoinpurity and chelation effects mainly contributed to the mixed scale inhibition. Further, the effect of β-CD-MA-SSS on the actual production wastewater was comprehensively evaluated from the technical, economic and environmental aspects.

Effect of multi-element synergistic addition on the microstructure evolution and performance enhancement of laser hot-wire cladded Fe-based alloy

To satisfy the requirements of hardness and corrosion resistance for laser additive manufacturing of hydraulic supports, this study applied the synergistic addition of C, B, Cr, Ni, Nb and Mo elements in Fe-based alloys. The multi-phases, martensite + austenite + ferrite were designed. The microstructure, hardness and corrosion resistance of the coatings were analyzed. Increasing the C and B contents could significantly increase the hardness of the coatings, while the corrosion resistance was decreased. The corrosion resistance of the coatings was determined by the Cr contents. However, increasing the Cr contents to 20.0 wt % resulted in the ferrite structure with lower hardness (21 HRC). The coatings with 0.25 wt % C, 1.2 wt % B and 19.0 wt % Cr showed the optimal matching of hardness (56 HRC) and corrosion resistance (survived in neutral salt spray test≥300h). The resulted coatings were mainly consisted of dendritic structure. Fine lath martensite phase was dominant in the dendrite regions. The interdendritic regions were consisted of nano-sized intermetallics with a mixture of σ+Nb + FeNb + Cr2Nb+(Fe,Cr)2B + NbC compounds. These interdendritic regions (14.2 GPa) showed higher hardness than that of the dendritic regions (7.1 GPa). The high Cr contents with finer dendritic structures were the major mechanisms for the excellent combination of hardness and corrosion resistance. The precipitation and growth mechanisms of the interdendritic phases were elaborated. This work provides a valuable reference for laser hot-wire cladding to prepare Fe-based alloys with high hardness and excellent corrosion resistance.

Influence of thermal history and consolidation force on wedge peel strength of CF/PEEK laminates manufactured by laser‐radiated in‐situ consolidation

AbstractProcessing parameters during the laser‐radiated in‐situ manufacturing process change the thermal history of the thermoplastic composite, which affects porosity and fiber‐resin interfacial bonding quality, and hence the wedge peel strength of the laminate. The effect of different laser powers and consolidation forces on the wedge peel strength of the specimens was investigated. Due to the fiber‐rich area on the tape surface during the laser heating phase as well as the insufficient consolidation force and consolidation length during the consolidation phase, the wedge peel strength decreased due to increased porosity and weak fiber‐resin bonding at the interlayer bonding interface. A conformable consolidation roller of lower hardness was used to improve the wedge peel strength of the laminates, which reduced the initial temperature of the cooling phase, thus inhibiting the void rebound and increasing the bonding strength at the fiber‐resin interface. The cross‐section and peeling surface were characterized by optical microscope and scanning electron microscope. The wedge peel strength of the laminates, with reduced voids and increased interfacial bonding strength between the fibers and the resin, is improved.Highlights Mechanism of void formation and evolution in different phases of laser‐radiated in‐situ consolidated laminate. Effect of consolidation roller hardness and deformation on wedge peel strength.

Experimental, density functional theory, molecular docking and ADMET analyses on the role of different plant extracts of Aronia melanocarpa (Michx) Elliot species on acetylcholinesterase enzyme activity

In the present study, different extracts obtained in different solvents from the fruits collected from the Aronia melanocarpa (Michx.) were prepared. The inhibition performances of these extracts on the inhibition of the acetylcholinesterase enzyme were checked via both theoretical and experimental analyses. Although all extracts used in experimental studies showed high inhibitory activity, it was observed that the extract obtained in methanol had higher inhibitory activity than the others. According to the enzyme activity results presented in the light of Ellman method, IC50 values were found between 0.0311–0.0857 mg/mL. Conceptual Density Functional Theory (CDFT) and Molecular Docking calculations were performed to identify the component or components of the extract with high inhibitory activity. Conceptual Density Functional Theoretical based data commented through popular electronic structure principles such as Maximum Hardness and Minimum Electrophilicity Principles showed that the most reactive one among studied dominant components of the extract is Malvin molecule. The interactions between studied molecules and AChE and mechanisms of these interactions were illuminated via Molecular Docking analyses and ADMET studies. As a result, it was shown that the most reactive molecule Malvin (with lowest hardness and the highest electrophilicity) interacts more powerful with AChE compared to other molecules. Within the framework of the theoretical analyses made, it was proposed that in the design and introduction of new AChE inhibitors, structures with low hardness and high electrophilicity values ​​should be preferred.

Effect of WC addition on microstructure and properties of laser melting deposited Ti6Al4V

Titanium alloys are generally characterized by low surface hardness, poor thermal conductivity, high friction coefficients and susceptibility to adhesive wear, which significantly hinder their industrial applications. To address this issue, we enhance the wear resistance of titanium alloys by incorporating nano WC particles. However, the optimal amount of WC to be added to titanium alloys remains unexplored. In this study, we prepared Ti6Al4V-xWC (wt%) (x = 0, 10, 20) coatings on Ti6Al4V substrates using laser melting deposition, specifically examining the effects of WC content on the microstructure and properties of the coating. The experimental findings indicate that the introduction of WC particles resulted in the formation of a TiC reinforced phase within the composite coating which promoted the equiaxialization of lamellae α phase. The hardness of the coatings increased significantly with the increase of the mass fraction of WC nanoparticles. Notably, the Ti6Al4V-10WC and Ti6Al4V-20WC coatings exhibited wear resistance that was 2.5 and 3.4 times greater, respectively, compared to the Ti6Al4V coatings. This enhancement in wear resistance can be attributed to the reinforcing phase (TiC) formed by the addition of WC. This experiment demonstrates a viable approach to improving the wear resistance of the Ti6Al4V titanium alloy through surface treatment.

Plasticization of a stiff pharmaceutical solid for better tabletability via cocrystallization: Shape synthons as supramolecular protecting groups

Extremely high particle stiffness and very low hardness is a serious concern in various mechanical processes in pharmaceutical manufacturing. Here we report an exceptionally high Young’s modulus (E) of ∼ 18 GPa in a drug, isoniazid (INH). This is one of the highest experimentally determined values among all reported pharmaceutical molecular crystals, which we attribute to the presence of a strong three-dimensional (3D) hydrogen bonding network (HBN). Further, we successfully reduced the 3D HBN in INH to 2D in its cocrystal using a co-former, 3,4-dimethylbenzoic acid (DMBA), where its two hydrophobic groups act like protecting groups at supramolecular level and prevent the extension of HBN. This reduced the E in the 1:1 cocrystal, INH-DMBA, by many folds and markedly improved its powder tabletability. To the best of our knowledge, this is the first reliable molecular level approach to alter the stiffness of pharmaceutical crystals and tabletability improvement in a predictable manner, hence, is important in the context of crystal engineering.

Investigation of Rolling Contact Fatigue Damage Behavior of a ER9 Wheel Tread in Relation to Surface Microstructural Evolution

In the present study, we systematically analyze the relationship between the surface microstructural evolution and rolling contact fatigue (RCF) damage behavior of the ER9 wheel tread. In the unfatigued zone (Zone A), where the shear stress was low, a thin plastic deformation layer with low hardness formed. The ferrite grains exhibited obvious plastic flow; however, these grains were not refined, and the cementite showed no significant fragmentation or dissolution. Additionally, the dislocation density remained low on the wheel surface in Zone A. Conversely, in the fatigue zone (Zone B), where the shear stress was high, a thicker plastic deformation layer with increased hardness developed. The ferrite grains in this zone were notably refined, and a substantial amount of lamellar cementite fragmented and dissolved, leading to a high dislocation density on the wheel surface. The severe plastic deformation in Zone B facilitated the formation of fatigue wear cracks on the wheel, which initiated the RCF crack in Zone B. Furthermore, the interface between pearlite and proeutectoid ferrite grains in the wheel accelerated the RCF crack propagation, ultimately leading to RCF failure.

Evaluation of wear resistance of CrN, CrAlN, and TiAlN coatings deposited by multi-arc ion plating on spinning die of Cr12MoV

Abstract This study successfully deposited CrN, CrAlN, and TiAlN coatings on the surface of Cr12MoV substrate using multi-arc ion plating (MAIP). The influence of phase composition and surface morphology on the hardness, adhesion strength, friction performance, and wear mechanisms of these coatings was investigated, with a comparative analysis of their wear resistance. Nanoindentation results revealed that the hardness (H) of CrN, CrAlN, and TiAlN coatings increased by 70.37%, 74.97%, and 75.64%, respectively, compared to the substrate. The hardness (H) and elastic modulus (E) were found to be positively correlated. CrAlN demonstrated superior resistance to deformation, reflected in its higher H/E and H 3 /E 2 radios compared to the CrN and TiAlN. Adhesion tests showed that CrAlN had the strongest adhesion strength to the substrate, with an adhesion force of 81.55 N, representing a 14.78% and 8.46% improvement over CrN and TiAlN, respectively. Friction and wear tests identified CrAlN as having the lowest friction coefficient (0.389), attributed to its high hardness and strong adhesion. The wear mechanisms of CrAlN observed were primarily mild abrasive wear, oxidative wear, and adhesive wear. In comparison, CrN and TiAlN coatings exhibited higher friction coefficients of 0.424 and 0.391, respectively, due to their lower hardness and adhesion, which led to more severe oxidative and abrasive wear. Additionally, the TiAlN coating showed signs of brittle failure in wear scars, likely due to the formation of Al2O3 oxides during wear.

Variation in microstructural features of melt-pool structure in laser powder bed fused Al–Fe–Cu alloy at elevated temperatures

The present study was undertaken to understand the effect of annealing on the microstructural features of the melt-pool structure and the associated multiscale mechanical properties of the Al–2.5%Fe–2%Cu alloy manufactured by laser powder bed fusion (LPBF). Microstructural characterizations and tensile tests were conducted for the LPBF-built specimen and those subsequently annealed at various temperatures ranging from 200 to 500 °C. Nanoindentation hardness mapping was used to evaluate the mechanical inhomogeneity of the melt-pool structure and its changes by annealing at different temperatures. The LPBF-manufactured sample exhibited a melt-pool structure containing numerous particles of the Al23CuFe4 phase (oC28, orthorhombic structure) formed because of local melting and rapid solidification during the LPBF process. The relatively coarsened cellular structure localized along the melt-pool boundary resulted in local soft regions. The local vulnerability contributed to the direction dependence of the tensile ductility. A slight variation was observed in the inhomogeneous microstructure of the samples annealed at 200 or 300 °C. The formation of numerous Al23CuFe4 nanoprecipitates in the α-Al supersaturated solid solution prevented strength loss after post-heat treatments. In addition, considerable coarsening of the intermetallic phase after annealing at 500 °C eliminated the melt-pool structure. The tensile performance of the specimens demonstrated a ductile fracture mode, wherein ductile fracture occurred in the α-Al matrix with low hardness while the harder θ-Al13Fe4 stable phase was embedded within it. The anisotropy in the mechanical properties was less pronounced owing to the significant microstructural changes.

Fracture strain improving via structural austenitic stainless steel-coated 22MnB5 plates

A total of 316 austenitic stainless steel (ASS) coatings were deposited on 22MnB5 press-hardening steel plates by varying the substrate bias voltages using a magnetron sputtering technique and quenched in a flat mold with cooling water. The substrate bias current and ion-bombardment energy densities increased up to 0.5 mA/mm2 and 50 J/mm2 at a high voltage of −100 V, and, therefore, the variations in the coatings’ morphologies were owing to the increases in the ion bombardment. The porous bulk pattern appeared in the quenched ASS coating at −100 V, clearly different from the porous columnar structure of the others at −50 and −75 V. The γ-Fe and α-Fe phases were observed from the diffraction peaks, presented the ASS coating and 22MnB5 substrate, respectively. There was no intermetallic compound (IMC) peak detected. In addition, the diffusion layer of the quenched ASS-coated plate was observed, in which its morphology was different from the quenched martensite (M) plate, and proved to be the α-Fe microstructure by the very low α-Fe peak at the standard (110) position. The bright image of TEM and the select area electron diffraction pattern indicated the nanostructure of the quenched ASS coating. The nanohardness of the ASS coating, diffusion layer, and M plate (7.36, 3.60, and 6.25 GPa, respectively) was detected, indirectly proving an α-Fe structure of the diffusion layer. The fracture angles of the 316-coated plates significantly improved from 51.82° at −50 V, 53.77° at −75 V to 57.38° at −100 V, as the ASS structure changed to be porous bulk pattern. The clearance of IMC, coating’s porous bulk pattern, and the low hardness α-Fe diffusion layer benefited for the fracture strain by lengthening the pathway of the crack’s development and blocking the further crack’s propagation, respectively.

Lattice-designed 3D printing of gluten-free pasta incorporated with xanthan gum for the elderly food

The use of xanthan gum (XG) has been reported to soften the texture of gluten-free pasta (GFP), making it an ideal food for the elderly with swallowing difficulties. Designing pasta shapes can enhance the suitability of sauces, improving sensory properties. This study aimed to investigate the optimal amount of XG for softening the texture of GFP. Three-dimensional (3D) printing was used to create lattice design shapes of the soft GFP, and sauce adhesion capacity (SAC) was investigated. The viscoelastic properties and yield stress values of the GFP dough significantly increased with higher XG contents (0.25%–2%) (p < 0.05), improving ink printability. The X-1% sample showed a decrease in the storage modulus (G’) (representing solid-like behavior) curve when the temperature increased from 68 °C, correlating with its lower hardness (5.11 × 104 ± 480 N/m2), which almost matched level 2 as the soft solid food that can be mashed with gums. This also agreed with its reduction in water-holding capacity (WHC) and its larger microstructural porosities. The SAC test demonstrated a significant relationship between 3D lattice design shapes and sauce viscosity, concluding that high- or low-viscous sauces may be suitable for the larger or smaller size of interior hole designs, respectively. This study provides guidance for developing novel 3D-printed GFP with a soft texture specifically designed to improve the mealtime experience for the elderly.

Classification of surface waters and groundwater in terms of drinking, agriculture, and industry

In this study, samples were collected from Seydoon River, The Alaa River, Galal Duparan Well, and Seyed Behzad Seepage Well near Seydoon River during the water year 2021-2022 for evaluation by the Khuzestan Water and Power Organization. Following laboratory analysis, Schuler and Wilcox diagrams were created using Aqua and Chemistry software to classify and interpret the water from The Seydoon River, The Alaa River, Duparan Well, and Seyyed Behzad Seepage Well. The objective of this study is to assess and comprehend the water quality of the rivers and wells in the region for drinking, industrial, and agricultural purposes. Overall, the groundwater in the area is deemed to be of medium to unsuitable quality for drinking. The well water is are classified as extremely hard. Furthermore, The Seydoon River and The Alaa River exhibit lower hardness levels compared to the groundwater in the region. in accordance with the Wilcox diagram, both surface and groundwater in the area are suitable in sodium absorption ratio for agricultural use, but they do face salinity issues. The water from The Seydoon River is suitable for industrial purposes, while The Seydoon River, The Alaa River, and Seyyed Behzad Seepage Well water is drinkable, and the water from Duparan Well is prone to forming deposits.

Effect of sputtering power and thickness ratios on the materials properties of Cu–W and Cu–Cr bilayer thin films using high power impulse magnetron and DC magnetron sputtering

This study investigates the influence of Cu thickness ratios on the structural, morphological, and mechanical properties of sputtered Cu–W and Cu–Cr bilayer thin films. Employing high power impulse magnetron sputtering (HiPIMS), five distinct thickness ratios of 1:3, 3:5, 1:1, 5:3, and 3:1 were analyzed and compared to bilayer films developed using direct current magnetron sputtering (DCMS). The microstructural and surface characteristics of these films were evaluated using x-ray diffraction (XRD), atomic force microscopy, and scanning electron microscopy. Electrical properties were measured using a four-point probe, while mechanical properties were assessed through nanoindentation. Results reveal that increasing Cu thickness in Cu–W and Cu–Cr bilayers inversely affects hardness, grain size, and roughness, highlighting the influence of thickness ratios on film properties. Films with a higher Cu thickness ratio in both Cu–W and Cu–Cr bilayer systems deposited by HiPIMS exhibited lower hardness, smaller grain size, and reduced average roughness. Cross-sectional analysis and XRD confirmed the impact of thickness ratio on crystal phase and microstructure, indicating smoother columnar structures. Specifically, the HiPIMS-deposited Cu–Cr 3-1 film exhibited the lowest resistivity, at 4.77 μΩ cm, and hardness, measuring 8.26 GPa. Moreover, the 1:1 ratio films of Cu–W and Cu–Cr demonstrated hardness values of 13.81 and 11.37 GPa, respectively, which were 1.39 times higher than the films grown by DCMS. Additionally, variations in the bilayer thickness ratio significantly affected the electrical properties of the films. The enhanced properties of HiPIMS films are attributed to the higher peak power density of the target, leading to increased ion energy and deposition of dense grain structures.

Self-formation of dual-phase nanocomposite Zr–Cu–N coatings based on nanocrystalline ZrN and glassy ZrCu

A novel type of nanocomposite Zr–Cu–N material based on hard nanocrystalline ZrN and amorphous glassy ZrCu was prepared by atom-by-atom deposition using reactive magnetron co-sputtering. The elemental composition of the coatings was systematically controlled over a wide range, so that the stoichiometry of both phases was the same in all coatings and only phase fractions varied. Experimental results obtained using X-ray diffraction and electron microscopies were complemented by thirteen ab-initio simulations for the same coating compositions. We found that the structure of the as-deposited Zr–Cu–N coatings undergoes a gradual transition from an amorphous to nanograined and finally to nanocolumnar structure. When ZrN fraction exceeds 20 mol.%, both phases exhibit the tendency for spontaneous segregation even without heating, forming a heterogenous dual-phase nanocomposite structure. At approximately 50 mol.% ZrN, the ZrN nanocrystals enveloped by a relatively thin amorphous ZrCu phase reach an optimum size (3–5 nm), resulting in a maximum enhancement of hardness by 38 % compared to the rule of mixture. For ZrN fractions > 80 mol.%, hardness and plastic work fraction follow the trend proposed by the rule of mixture and the coatings with a lower hardness but a higher plasticity compared to the ZrN coating are prepared.