High-strength and thermally stable TiB_(2)-modified Al-Mn-Mg-Er-Zr alloy fabricated via selective laser melting

To increase the processability and plasticity of the selective laser melting(SLM)fabricated Al-Mn-Mg-Er-Zr alloys,a novel TiB_(2)-modified Al-Mn-Mg-Er-Zr alloy with a mixture of Al-Mn-Mg-Er-Zr and nano-TiB_(2) powders was fabricated by SLM.The pro-cessability,microstructure,and mechanical properties of the alloy were systematically investigated by density measurement,microstruc-ture characterization,and mechanical properties testing.The alloys fabricated at 250 W displayed higher relative densities due to a uni-formly smooth top surface and appropriate laser energy input.The maximum relative density value of the alloy reached(99.7±0.1)%,demonstrating good processability.The alloy exhibited a duplex grain microstructure consisting of columnar regions primarily and equiaxed regions with TiB_(2),Al6Mn,and Al3Er phases distributed along the grain boundaries.After directly aging treatment at a high tem-perature of 400℃,the strength of the SLM-fabricated TiB_(2)/Al-Mn-Mg-Er-Zr alloy increased due to the precipitation of the secondary Al6Mn phases.The maximum yield strength and ultimate tensile strength of the aging alloy were measured to be(374±1)and(512±13)MPa,respectively.The SLM-fabricated TiB_(2)/Al-Mn-Mg-Er-Zr alloy demonstrates exceptional strength and thermal stability due to the synergistic effects of the inhibition of grain growth,the incorporation of TiB_(2) nanoparticles,and the precipitation of secondary Al6Mn nanoparticles.

Influence of process parameters and aging treatment on the microstructure and mechanical properties of Al Si8Mg3 alloy fabricated by selective laser melting

Many studies have investigated the selective laser melting(SLM)of AlSi10Mg and AlSi7Mg alloys,but there are still lack of researches focused on Al-Si-Mg alloys specifically tailored for SLM.In this work,a novel high Mg-content AlSi8Mg3 alloy was specifically designed for SLM.The results showed that this new alloy exhibited excellent SLM processability with a lowest porosity of 0.07%.Massive lattice distortion led to a high Vickers hardness in samples fabricated at a high laser power due to the precipitation of Mg_(2)Si nanoparticles from theα-Al matrix induced by high-intensity intrinsic heat treatment during SLM.The maximum microhardness and compressive yield strength of the alloy reached HV(211±4)and(526±12)MPa,respectively.After aging treatment at 150℃,the maximum microhardness and compressive yield strength of the samples were further improved to HV(221±4)and(577±5)MPa,respectively.These values are higher than those of most known aluminum alloys fabricated by SLM.This paper provides a new idea for optimizing the mechanical properties of Al-Si-Mg alloys fabricated using SLM.

Tribological performance under different environments of Ti-C-N composite films for marine wear-resistant parts

The need for reducing the wear in mechanical parts used in the industry makes self-lubricant films one of the sustainable solutions to achieve long-term protection under different environmental conditions.The purpose of this work is to study the influence of C additions on the tribological behavior of a magnetron-sputtered TiN film in air,water,and seawater.The results show that the addition of C into the TiN binary film induced a new amorphous phase,and the films exhibited a dual phase of fcc(face-centered cubic)-TiN and amorphous carbon.The antifriction and wear-resistance properties were enhanced in air and water by adding 19.1at%C.However,a further increase in the C concentration improved anti-frictional properties but also led to higher wear rates.Although the amorphous phase induced microbatteries and accelerated the corrosion of TiN phases in seawater,the negative abrasion state was detected for all Ti-C-N films due to the adhesion of the tribocorrosion debris on the wear track.

Erratum to:Influence of process parameters and aging treatment on the microstructure and mechanical properties of AlSi8Mg3 alloy fabricated by selective laser melting

Erratum to:International Journal of Minerals, Metallurgy and MaterialsVolume 29, Number 9, September 2022, Page 1770https://doi.org/10.1007/s12613-021-2287-1The original version of this article unfortunately contained a mistake due to the PDF file conversion through different softwares. The presentation of Fig. 13 in original version was incorrect.

Nano-multilayered ZrN‒Ag/Mo‒S‒N film design for stable anti-frictional performance at a wide range of temperatures

A multilayer film,composed by ZrN‒Ag(20 nm)and Mo‒S‒N(10 nm)layers,combining the intrinsic lubricant characteristics of each layer was deposited using DC magnetron sputtering system,to promote lubrication in a wide-range of temperatures.The results showed that the ZrN‒Ag/Mo‒S‒N multilayer film exhibited a sharp interface between the different layers.A face-centered cubic(fcc)dual-phases of ZrN and Ag co-existed in the ZrN‒Ag layers,whilst the Mo‒S‒N layers displayed a mixture of hexagonal close-packed MoS_(2)(hcp-MoS_(2))nano-particles and an amorphous phase.The multilayer film exhibited excellent room temperature(RT)triblogical behavior,as compared to the individual monolayer film,due to the combination of a relative high hardness with the low friction properties of both layers.The reorientation of MoS_(2)parallel to the sliding direction also contributed to the enhanced anti-frictional performance at RT.At 400℃,the reorientation of MoS_(2)as well as the formation of MoO_(3)phase were responsible for the lubrication,whilst the hard t-ZrO_(2)phase promoted abrasion and,consequently,led to increasing wear rate.At 600℃,the Ag_(2)MoO_(4)double-metal oxide was the responsible for the low friction and wear-resistance;furthermore,the observed transformation from t-ZrO_(2)to m-ZrO_(2),could also have contributed to the better tribological performance.

Strengthening mechanisms of high-performance Al-Mn-Mg-Sc-Zr alloy fabricated by selective laser melting

Selective laser melting(SLM)can efficiently fabricate metallic components with complex shapes and offers new opportunities for the structural optimization of lightweight components[1].Owing to the high cooling rate(10^(3)-10^(6)Ks^(-1))of the SLM process,the solidified SLM-fabricated metals show a unique microstructure with highly supersaturated solid solutions that are well beyond the normal solubility limits of most elements.This leads to significant improvements in the mechanical properties of the SLM-fabricated materials[2].

An Ultra-High Strength Over 700 MPa in Al-Mn-Mg-Sc-Zr Alloy Fabricated by Selective Laser Melting

Selective laser melting(SLM)provides optimized lightweight structures for aircraft and space applications.However,the strength of the current SLMed aluminum alloys is still lower than that of the traditional high-performance aluminum alloys.This study presents an ultra-high-strength Al-Mn-Mg-Sc-Zr aluminum alloy specifically designed for SLM by increasing the(Mg+Mn)and(Sc+Zr)content simultaneously based on the rapid solidification characteristics of the SLM process.The alloy exhibits good SLM processability with a minimum porosity of 0.23%.After aging at 300℃,the strength of the alloy was effectively improved,and the anisotropy of mechanical properties was reduced.Additionally,the tensile yield strength and ultimate tensile strength of the alloy reached 621±41 MPa and 712±28 MPa,respectively;these values are superior to those of most SLMed aluminum alloys reported previously.Multiple strengthening mechanisms including solid solution strengthening,precipitation strengthening and grain refinement strengthening contribute to the high strength of the present alloys.

Controllably grown single-crystal films as flexoelectric nanogenerators for continuous direct current output

Until now,conventional nanogenerators could only produce electric pulses with relatively low-power densities.Herein,we invent a novel controllable growth technique for two-dimensional(2-D)cuprous oxide(p-Cu2O)single-crystal films,and on this basis,a new concept of 2-D single-crystal film flexoelectric nanogenerators(FENGs)are rationally designed and constructed for the first time,which has the characteristics of long-range order lattice,few grain boundaries and defects.More importantly,the accumulated built-in polarization potential in the bent 2-D p-Cu2O single-crystal film FENGs is in the same orientation as the output electricity,resulting in the first nanogenerator that can output continuous and stable electric signals with high voltage(Voc of 2.8 V),current(Jsc of 11.5μA·cm^(-2))and power density(14.4μW·cm^(-2)),exhibiting great practical application potential for power generation and motion capture.This research breaks new ground and establishes a precedent for high-performance and continuous-output nanogenerators,as well as smart wearable sensors.

Preparation and Properties of Superhydrophobic ZnO Nanorod-based Nanocomposite on the Surface of Stainless Steel Mesh

Bionic superhydrophobic coating has extremely broad application prospects and practical value. It is based on two important conditions, one is the construction of micro–nano structure, the other is the material with low surface energy. How to stabilize the micro–nano structure has become the focus of researches. In this work, a layer of Zn film is deposited on the stainless steel mesh with sturdy micron structure by RF magnetron sputtering. The solid micron structure of the stainless steel mesh itself, combined with the method of thermal oxidation, the surface of the stainless steel mesh is thus formed into a nanorod like ZnO nano structure, and then modified with perfluorodecyltriethoxysilane (PFDS) for low surface energy. The maximum contact angle of the superhydrophobic sample is 154.8°, and the minimum sliding angle is 2°, and it also has excellent corrosion resistance, thermal stability, self-cleaning, anti-aging and anti-icing properties, which provides a design idea for the preparation of superhydrophobic coatings.

Robust Polystyrene/Fluorinated Silica Superhydrophobic Composite Coatings with Rapid Curing at Room Temperature Prepared by One-Step Spraying

Superhydrophobic materials are severely limited in their applications due to their weak mechanical properties and complex preparation process.In this paper,polystyrene/fluorinated silica(PS/SiO_(2))superhydrophobic composite coatings were prepared on the surface of 304 stainless steel using a simple one-step spraying method.The effects of different PS contents on the wettability as well as the wear properties of the samples were investigated.SiO_(2) was encapsulated in polystyrene to form a structure similar to cement encapsulated stones.With the addition of PS,a mound-like structure was formed on the sample surface,and a more optimized micro–nano structure was obtained when the content of PS was 0.6 g.At this time,the sample exhibited excellent wettability with a contact angle of 157.86°and a sliding angle of 0.84°.In addition,the contact angle of 151.09°was achieved after 180 cm of friction under a 100 g load and the composite coating prepared by this method also has excellent chemical stability,water impact resistance,corrosion resistance,and self-cleaning properties.This opens up new possibilities for the development of simple and robust superhydrophobic materials.

Enhanced figure of merit for famatinite Cu_(3)SbSe_(4)via band structure tuning and hierarchical architecture

The p-type Te-free Cu_(3)SbSe_(4)with famatinite structure is a potential candidate for thermoelectric materials due to the low cost and eco-friendly constituent elements.However,its strong bipolar effect and high lattice thermal conductivity(klat)are the main challenges for its performance enhancement.Herein,we report a new strategy to enhance its figure of merit zT~0.86 at 673 K for Cu_(3)Sb_(0.95)Fe_(0.05)Se_(2.8)S_(1.2)via band structure tuning and hierarchical architecture.Firstly,S substituted Se atoms in lattice can widen the band gap to alleviate the bipolar effect.Secondly,Fe doping in Sb site significantly increases the density of states,thus increasing the carrier effective mass,and obtaining a remarkably high Seebeck coefficient of~560 mV/K at 300 K.Moreover,the induced hierarchical architecture defects resulting in a minimum klat of~0.48 W·m^(-1)·K^(-1)at 673 K.Consequently,the improved Seebeck coefficient combined with low thermal conductivity leads to an enhanced zT.

Predicting microRNA-disease association based on microRNA structural and functional similarity network

Background:Increasing evidences indicate that microRNAs (miRNAs) are functionally related to the development and progression of various human diseases.Inferring disease-related miRNAs can be helpful in promoting disease biomarker detection for the treatment,diagnosis,and prevention of complex diseases.Methods:To improve the prediction accuracy of miRNA-disease association and capture more potential diseaserelated miRNAs,we constructed a precise miRNA global similarity network (MSFSN) via calculating the miRNA similarity based on secondary structures,families,and functions.Results:We tested the network on the classical algorithms:WBSMDA and RWRMDA through the method of leaveone- out cross-validation.Eventually,AUCs of 0.8212 and 0.9657 are obtained,respectively.Also,the proposed MSFSN is applied to three cancers for breast neoplasms,hepatocellular carcinoma,and prostate neoplasms.Consequently,82%,76%,and 82% of the top 50 potential miRNAs for these diseases are respectively validated by the miRNA-disease associations database miR2Disease and oncomiRDB.Conclusion:Therefore,MSFSN provides a novel miRNA similarity network combining precise function network with global structure network of miRNAs to predict the associations between miRNAs and diseases in various models.