Resistant Alloys Research Articles

Enhancing the fatigue resistance of high and medium entropy alloys by manufacturing-driven microstructural developments

Excellent fatigue performance is essential for broader applications of structural materials. In the present work, we report a microstructural design that improves fatigue resistance for high and medium-entropy alloys fabricated by direct energy deposition and hot-rolling processes. Specifically, we discover that the concurrent evolution of microstructures with fine-structure, including stacking faults, nano-twins and hexagonal-close-packed (HCP) structures, leads to zig-zag fracture that hinders crack propagation under cyclic loadings. These multiple characteristic microstructures improve fatigue resistance, which are attributed to the combination of low effective stacking fault energy and a high capacity for strain energy density. Anisotropic microstructural evolution is driven by the correlation between partial dislocations and the resolved shear stresses depending on the crystallographic orientation relationship. Consequently, stacking faults and nano-twins form prominently in the {111} grains under tension and in the {200} grains under compression. The current work provides an effective method to design advanced alloys for high fatigue resistance through microstructural tuning that controls the stacking fault energy combined by manufacturing processes.

Subsurface deformation mechanism and the interplay relationship between strength-ductility and fretting wear resistance during fretting of a high-strength titanium alloy

Fretting wear damage of high-strength titanium fasteners has caused a large number of disastrous accidents. Traditionally, it is believed that both high strength and excellent ductility can reduce fretting wear damage. However, whether strength and ductility are contradictory or not and their appropriate matching strategy under the external applied normal stress (Fw) are still confusing problems. Here, by analyzing the subsurface-microstructure deformation mechanism of several samples containing various α precipitate features, for the first time, we design strategies to improve fretting damage resistance under different matching relation between Fw and the tensile strength of materials (Rm). It is found that when Fw is greater than Rm or Fw is nearly equivalent to Rm, the deformation mechanism mainly manifests as serious grain fragmentation of β and αGB constituents. Homogeneous deformation in large areas only reduces damage to a limited extent. It is crucial to improve the strength to resist cracking and wear, but it is of little significance to improve the ductility. However, when Fw is far less than Rm, coordinated deformation ability reflected by ductility plays a more important role. The deformation mechanism mainly manifests as localized deformation of β and αGB constituents (kinking induced by twinning and spheroidizing). A unique composite structure of nano-grained/lamellar layer and localized deformation transition layer reduces fretting damage by five times compared with a single nano-grained layer. Only when the strength is great enough, improving the plasticity can reduce wear. This study can provide a principle for designing fretting damage resistant alloys.

Methods of neutralization of iron-containing phases in cast aluminum alloys of the Al-Si-Cu system with iron content of up to 1,5 mass. %

The article discusses the effectiveness of various modifiers, namely chromium (Cr), molybdenum (Mo), vanadium (V), and cobalt (Co), in neutralizing the negative impact of iron on the properties of aluminum alloys in the Al-Si-Cu system by altering the morphology of iron-containing phases. The current advancements in the modification of aluminum alloys are examined, focusing on the influence of these elements on microstructural changes and mechanical properties. An in-depth analysis of the microstructure was conducted, and the optimal concentrations of the modifying elements were identified to achieve enhanced mechanical characteristics. The study highlights that the addition of Cr, Mo, V, or Co facilitates the formation of a fine-grained structure and significantly reduces the size of iron-containing phases to approximately 10 μm. Furthermore, the research elaborates on the thermodynamic interactions between iron and the modifying elements, providing insights into the mechanisms by which these modifiers influence the crystallization process and phase distribution within the alloy. This study opens new avenues for the development of high-performance aluminum alloys with optimized microstructures through precise control of modifier concentrations. The improved alloys exhibit superior mechanical properties, making them suitable for applications in various industrial sectors, including automotive and other industries, where high strength and reliability are critical. Experimental results demonstrate that the strategic addition of Cr, Mo, V, and Co can effectively mitigate the adverse effects of iron inclusions, leading to alloys with enhanced ductility, tensile strength, and overall performance. The findings suggest that these modifiers not only refine the grain structure but also promote a more uniform distribution of phases, thus improving the alloy's resistance to cracking and other forms of mechanical failure. The insights gained from this research provide a valuable foundation for further exploration and optimization of aluminum alloys for high-demand applications, emphasizing the critical role of microstructural engineering in achieving desired material properties

Non-conventional Manufacturing using the EDAS Method

A process that uses mechanical energy is conventional machining. Alternative energy sources are used by unconventional machines. In non-conventional machining, the three main types of energy are thermal, chemical, and electrical. non-standard machining, also referred to as modern machining, is a machining technique that removes, deforms, and modifies the properties of materials such as plates by utilizing electricity, energy types include electromagnetic energy, bio fuels, acoustic energy, electrochemical energy, and thermal energy. Tools and work pieces are in direct touch during conventional machining procedures. The tool and indeed the work piece do not have to come into physical contact for non-traditional machining procedures to work. The distinctions between conventional and non-conventional machining processes are examined in this article. The lead phase is typically coated using a paste made from a combination of lead & lead oxide powder, additives, and the necessary amount of acid and water after the sulphated mixture has been reduced to a fine lead mass to achieve the requisite density. On the other hand, non-conventional machining uses the most recent and cutting-edge processing technologies. No materials or machine tools come into contact with each other throughout this operation. Electric beam, electric arc, plasma cutting, and infrared beam are a few examples of non-conventional tools in use. Complex forms can be machined using those atypical machining techniques, in part due to the utilisation of cutting-edge CNC technology. The usage of these procedures is frequently determined by the material's shear strength, for instance, when wear resistant alloys and special combinations are involved. In order to create complicated and exact shapes in materials like titanium, stainless steel, high - temperature short (HSTR) alloys, jute composites, ceramics, refractories, and other hard materials, nontraditional machining (NTM) procedures are now often used. The goal of the current investigation using mechanical composites is to ascertain its effect. Brazilian consumers' food purchase intentions are influenced by a variety of manufacturing techniques, brands, prices, and labels. high-grade vegetable oils. Solvents, which may be hazardous, are used in conventional manufacturing processes. The environment suffers as a result. Change Manufacturing procedures, which don't require solvent use might necessitate the use of cutting-edge technologies like plant genetic engineering. looking into the use of genetic modification utilised in food production has a greater potential for reducing environmental effect. The EDAS score primarily based on the space from the suggest agreement machine is the installed energy for a manufacturing plant. Experts' critiques and derived numbers do not trust each different concerning solar energy and geothermal electricity. Traditional, Genetic engineering, High, Sunflower and Green globe. Smart Restaurant, Restaurant Automation, Device-to-Device Communication, Near Field Communications based, Smart Cities and Cloud Computing. Non-Conventional Manufacturing. Green globe is got the first rank whereas is the Sunflower is having the Lowest rank. Non-Conventional Manufacturing. Green globe is got the first rank whereas is the Sunflower is having the Lowest rank.

Process design and experimental study on drilling operations of a hybrid aluminum/carbon fiber reinforced polymer/titanium composite

ABSTRACT Carbon fiber reinforced composites (CFRP) are increasingly used in aviation and automotive industries. To enhance rigidity and fatigue resistance, aluminum (Al) and titanium (Ti) alloys are used together with CFRP materials. Drilling is a common method for manufacturing these hybrid composite stacks. This study examines the impact of process parameters, temperature, tool wear, thrust force, and torque on CFRP/Al/Ti hybrid composites during dry machining. Tests were conducted at various drilling speeds, feed rates, and stack orders using a solid carbide (WC) cutting tool. Results indicate that feed rate has a significant effect on the process outputs. The temperature remains low as the feed rate rises. The delamination factor is the highest in the Ti\\CFRP\\Al stack. In addition, delamination and temperature rise with increasing cutting speed. Finally, while the Al\\CFRP\\Ti stacking order performs poorly in terms of tool wear, it is measured more than 330 micrometers at the lowest feed rate.

Design of hydrogen embrittlement resistant 7xxx-T6 aluminum alloys based on wire arc additive manufacturing: Changing nanochemistry of strengthening precipitates

In this work, atom probe tomography technique is used to investigate how wire arc additive manufacturing (WAAM) changes the nanochemistry of nanoprecipitates and grain boundaries after peak aging of a high strength Al-Zn-Mg-Cu alloy. The effect of the change in nanochemistry of nanoprecipitates on the hydrogen embrittlement of the additively manufactured aluminum alloy is investigated using a three-point bending test in humid air. The results show that the unique in-process heat treatment during WAAM, offers the possibility to modify the nanochemistry of nanoprecipitates and improve the resistance to hydrogen embrittlement of the Al-Zn-Mg-Cu alloys in the peak aged state without sacrificing mechanical performance. Density functional theory shows that the WAAM process transforms the interfaces between matrix and precipitate into a strong hydrogen trap, which can reduce the hydrogen content of grain boundaries and suppress hydrogen-induced intergranular fracture.

Corrosion performance of different alloys exposed to HTL conditions—A screening study

AbstractThe corrosion and material evaluation study in (a) water‐based simulated black liquor and (b) water‐based simulated black liquor at super‐critical conditions was successful. The conclusion from the testing program was that the most resistant alloy for the defined conditions is the chromium‐rich carbon steel candidate P91 (UNS K91560). This is a type of creep strength‐enhanced ferritic alloy, which is steel designed to retain strength at high temperatures. The P91 abbreviation represents the material's chemical composition, that is, 9 wt% chromium (Cr) and 1 wt% molybdenum (Mo). Further work is required to conclude the corrosion resistance for the P91 quality at supercritical conditions in the welded condition and to better understand caustic corrosion mechanisms.

Oxidation resistant low-alloyed Ti alloys with good ductility

Oxidation resistant low-alloyed Ti alloys with good ductility

Effect of different quenching holding times on microstructure, texture and electrical resistivity of NiCrAlFe alloy

Quenching treatment can provide microstructure for subsequent tempering treatment in the production process of NiCrAlFe precision resistance alloy. However, the recrystallization texture formed during quenching will be inherited into the tempered alloy, causing anisotropy of resistance and affecting the final performance of precision resistors. In order to investigate the evolution of the texture and its influence on the anisotropy of resistance, the effect of various quenching holding times on the alloy were studied. The results indicate that certain rolling deformation texture is gradually transformed into recrystallization texture and the texture intensity decreases significantly during the holding process. At the same time, the formation of a large number of twins promotes the formation of Brass-R {111}<112> texture at twin boundaries. The electrical resistivity of the alloy changes from 1.360 μΩ·m to 1.427 μΩ·m, and it shows an increasing trend with the holding time. The large number of supersaturated vacancies generated by quenching is the main reason for the increase in alloy electrical resistivity, but there is no correlation between the orientation density of texture and the electrical resistivity, however the type and intensity of textures exhibit significant influence on the anisotropy of the electrical resistivity. The electrical resistivity of direction rolling, direction 45°, and direction 65° are mainly influenced by Goss {110}<001> texture, Goss {110}<001> texture and Brass-R {111}<112> texture, and S {123}<634> texture and R {124}<211> texture, respectively.

In situ electrochemical deposition enables dense polypyrrole grown on AZ31 surface for improving corrosion resistance

This study addresses the poor corrosion resistance of Mg alloy. Based on an in-situ electrochemical strategy, poly(pyrrole) coatings were selectively prepared on the surface of Mg alloys with controlled thickness using constant current and cyclic voltammetry techniques. The results indicate that PPy-CV coatings possess greater thickness and a denser structure. Combining studies on corrosion behaviors such as electrochemical analysis, and immersion, it was found that the coatings effectively prevent solution intrusion, thereby enhancing the alloy's resistance to corrosion. And also provides a new avenue for designing corrosion-resistant coatings, particularly for conductive materials such as polyaniline, poly(3,4-ethylenedioxythiophene), etc.

Effect of ultrasonic vibration-assisted laser cladding frequency on the microstructure and properties of Fe-0.5C-15Cr alloy cladding layers

In this paper, Fe-0.5C-15Cr wear and corrosion resistant alloy coating was prepared on 3Cr13 stainless steel surface by ultrasonic vibration assisted laser cladding technology. The effects of ultrasonic vibration frequency on the microstructure, microhardness and corrosion resistance of the coating were studied. The results show that the length of the dendrites of the cladding layer decreased significantly after ultrasonic vibration is applied, the grains size is refined significantly, and the morphology of the grain boundary carbides changed from fishbone-like to short rods, when the vibration frequency is 20.2 kHz, the grain refinement is the most significant, and the orientation of the dendrites is obviously weakened. The hardness of the applied ultrasonic vibration specimens increased by 10–20 HV0.2 relative to the non-ultrasonic specimens, with the increase of vibration frequency, the hardness of the cladding layer firstly increased and then slightly decreased, and the peak appeared at 20.2 kHz. The coefficient of friction of the specimens when the ultrasonic frequency of 20.2 kHz is applied is lower than that of the specimens with non-ultrasonic frequency by 12.8 %, and the abrasive wear rate is reduced by 14.3 %. After ultrasonic vibration, the pitting potential of the cladding layer increases, the dimensional passivation current density decreased, the width of the passivation zone becomes wider, and the intergranular corrosion reactivation rate decreased, When the ultrasonic frequency is 20.2 kHz and 20.4 kHz, the pitting corrosion resistance and intergranular corrosion resistance of the cladding layer are significantly improved. This is because the cavitation effect, resonance effect and acoustic flow effect of ultrasonic vibration promote the non-uniform nucleation, refine the dendrites and intergranular carbides, and promote the redistribution of the corrosion-resistant element Cr in the in-grain martensite and grain boundary carbides, increasing the content of Cr in the matrix, and thus improving the wear resistance and corrosion resistance of the cladding layer.

Effect of TiB2 on the mechanical and tribological properties of marine grade Aluminum Alloy 5052: An experimental investigation

Aluminum Alloy 5052 is one of the excellent corrosion resistant alloys among the Aluminum 5000 series alloys. Despite the favourable corrosion resistance, it exhibits low resistance to wear and perform poorly in various tribological applications. This study attempts to investigate the impact of TiB2 reinforcement on the mechanical and tribological properties of Aluminum Alloy 5052 matrix alloy, fabricated using the stir casting technique. Composites with varying weight percentages (0, 2.5, 5 and 7.5 wt %) of TiB2 were prepared. Vicker's hardness testing was conducted to assess the effect of TiB2 content on composite hardness. Hardness of composites increased from 65.5 to 85.16 HV in tandem with the TiB2 content depicting a rise of about 30 %. Tribological properties were studied through dry sliding wear tests using a pin-on-disc tribometer, with varying loads (10 N and 50 N) and sliding speeds (1 m/s and 3 m/s). The results demonstrate that the addition of TiB2 significantly improves the wear resistance of the composites, being optimum in composite with 5 wt % of TiB2. A maximum increase of about 36 % in wear resistance was observed at high load and high-speed conditions corresponding to 5 wt % TiB2 concentration. FESEM analysis revealed distinct wear modes and the role of TiB2 in changing the wear mechanism from abrasion to delamination. This study underscores the pivotal role of TiB2 in enhancing the mechanical and tribological properties of Aluminum Alloy 5052, expanding its application scope, particularly in lightweight engineering applicationsin general and marine in particular.

Application of plasma-sprayed AlxCrCoFeNi High-Entropy alloys for high-temperature oxidation resistance

The HEAs were deposited in the form of coatings by using a plasma spraying process on SS-304 substrate material. The fraction x was varied from 0 to 1(x = 0, x = 0.5, and x = 1) for Al in the HEAs and three coatings were deposited. The high-temperature oxidation test was conducted at 800 °C for 50 cycles. The Al1CrCoFeNi coating has demonstrated maximum oxidation resistance. The microhardness was found to be maximum in the case of Al1CrCoFeNi High-Entropy alloy coating (540 ± 11 HV0.3). The main reason for the enhanced performance is the solid solution strengthening in high-entropy alloys (HEAs) due to a mismatch in atomic size differences among the elements, which is caused by the substantial lattice distortion caused by the higher aluminum content.

Wear and Corrosion Resistant Eutectic High-Entropy Alloy Al0.3CoCrFeNiMo0.75 Produced by Laser Metal Deposition and Spark-Plasma Sintering

Eutectic high-entropy alloys (EHEAs) with a fine-lamellar structure and homogenous property profile are of particular interest for wear and corrosion protection coatings. High cooling rates in the laser metal deposition (LMD) process can induce microstructure refinement and allow the formation of a supersaturated solid solution in EHEAs. A subsequent solution annealing can create the equilibrium state. In the present study, LMD coatings with an ultrafine-grained Widmanstätten structure were produced from the EHEA Al0.3CoCrFeNiMo0.75 gas atomized powder. High cooling rates during deposition led to a supersaturated solid solution with face-centered cubic (FCC) structure. The LMD coating exhibits the highest average hardness of 734 HV0.5, which drops to approx. 200 HV0.5 due to an increased microstructural domain size after heat treatment. Under oscillating wear, the formation of oxidized wear debris promotes material removal in the heat-treated condition. Corrosion tests reveal a deterioration of the passivation behavior. LMD processes exhibit great potential to create supersaturated solid solutions with refined structure in EHEAs to enhance the property profile.

Same-spot micro-ECM based on constant-accelerated movement of the electrode

ABSTRACT An injector nozzle needs a precision upside-down tapered-microhole, and the nozzle material is often a high temperature corrosion resistant alloy that is very difficult to machine. In this study, a same-spot micro-ECM technique with the electrode in “constant-accelerated movement” was proposed. Insulated by electrophoretic deposition, an ultra-fine electrode was inserted deep into the hole and subject gradually to withdrawal from the hole at constant rpm and acceleration. The electric flux intensity acting on the hole-wall gradually decreased and so did the material dissolution rate on the hole-wall, thus creating an upside-down tapered hole with the desired taper-rate. The experiments’ results showed that upside-down tapered holes with taper-rates of T(a=1) = 0.094 (Ra 0.593 μm) and T(a = 2) = 0.02 (Ra 0.435 μm) were produced when the electrode was subject to constant-acceleration withdrawal at 1.0 and 2.0 μm/s2, respectively, and respective spray angles of 31° and 23° were created. The proposed technique is commercially promising in industry.

Experimental programme on austenitic stainless steel RHS members subjected to monotonic and cyclic bending

Stainless steel is a corrosion resistant iron alloy with great potential in structural engineering due to its excellent mechanical features, durability and aesthetic properties. Since most of the existing research has concerned the behaviour of the material, the response of individual structural members, or the performance of simple structural systems under monotonic loading, one of the challenges that remains is the evaluation of the cyclic performance of members to promote its use in seismic design and exploit the excellent ductility and strain hardening properties of this material. For this reason, an experimental programme on austenitic stainless steel Rectangular Hollow Section (RHS) specimens was carried out at the Department of Civil Engineering of the Università degli Studi di Salerno in collaboration with the Universitat Politècnica de Catalunya. A total of eight RHS specimens were tested around the minor axis under both monotonic (three specimens) and cyclic (five specimens) loading, in an experimental set-up that followed a cantilever scheme. The main purpose of this study was to acquire information on the cyclic performance of austenitic steel structural members, focusing on the comparison between monotonic and cyclic behaviours. The outcomes of the tests included the load–displacement and the moment–rotation curves, the energy dissipation capacity, and the evaluation of the key rotation capacities of the members. The reported data are essential to enhance the still scarce research on the seismic behaviour of stainless steel structures.

The Effects of Thermal History on Toughness of Ni-Based Corrosion Resistant Alloys during In Situ Hydrogen Charging

The Effects of Thermal History on Toughness of Ni-Based Corrosion Resistant Alloys during In Situ Hydrogen Charging

Fabrication of a sustainable superhydrophobic surface of Ag-NPs@SA on copper alloy for corrosion resistance, photocatalysis, and simulated distribution of Ag atoms.

Artificial superhydrophobic surfaces that do not absorb water, like the lotus leaf, show tremendous promise in numerous applications. However, superhydrophobic surfaces are rarely used because of their low stability and endurance. A stable organic superhydrophobic surface (SHS) composed of novel morphology Ag-nanoparticles (NPs) has been fabricated on a copper alloy via etching, immersion, spraying, and annealing treatment, along with a static water contact angle (WCA) of 158 ± 1° and sliding angle (SA) less than 2°. The surface texture, composition, and morphology of the substrate surfaces were explored by using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and DFT-based Ag atom distribution. The anti-corrosion study of non-coated and Ag-NP-coated copper alloy was undertaken using electrochemical impedance spectroscopy. Ag-NPs +SA@SHS enhanced the corrosion resistance as compared with bare Cu alloy. The water droplet rolled down the coated Cu alloy, removed the chalk powder from the surface, and indicated an excellent self-cleaning function. Photodegradation of Congo red (CR) and methylene blue (MB) dye samples was assessed by measuring the absorbance through UV-Visible spectrophotometry, where the Ag-NPs coated on the copper alloy were used as a catalyst. The performance of the SHS@Ag-NPs in the aqueous solution was 99.31% and 98.12% for industrial pollutants (CR and MB), with degradation rates of 5.81 × 10-2 s-1 and 5.89 × 10-2 s-1, respectively. These findings demonstrated a simple, rapid, and low-energy fabrication technique for SHS@Ag-NPs. This research reveals a valuable approach for the fabrication of SHS@Ag-NPs on various substrates to extend the superhydrophobic surfaces with ultra-fast self-healing properties, for outdoor applications such as anti-corrosion, for an innovative approach for the remediation of polluted water treatment, and for industrial applications.

A new tensile creep model for predicting long-term creep strengths with short-term test data for creep resistant alloys

The difficulties in using the conventional Norton creep model to rationalise short-term creep data and to subsequently predict long-term creep rupture strengths for creep resistant alloys are presented and analysed. The results of this study show that these difficulties can be resolved if a new tensile creep model that integrates the tensile strength at creep temperature is applied to rationalise the short-term creep data. This is illustrated with the creep and tensile strength data measured for a grade of Ni-based superalloy. Based on this new tensile creep model, the activation energy of creep determined is independent of stress and the stress exponent is not influenced by temperature. Consequently, the model constants obtained from the short-term creep data can be applied together with the Monkman-Grant relationship to make the long-term creep rupture strength predictions at different temperatures. The factors affecting the reliability of the predictions made by this method are also analysed.

Enhancing corrosion and tribology performance of stainless steel with DLC coatings: Effects of doping and multilayered structures

The increasing demand for energy production has expanded oil and gas extraction, particularly in harsh exploration sites with highly corrosive media. In the Brazil's pre-salt layer, rich in oil reserves, high NaCl content and CO2 presence may induce sweet corrosion. Corrosion resistant alloys are often used for better performance, and among them, austenitic stainless steels (SS) offer good balance of cost and properties. However, pre-salt acidic and salty environment may induce localized corrosion, making protective coatings a viable option to prolong the lifespan of components exposed to these environments. Diamond-like carbon (DLC) coatings are a great alternative, as besides being chemically stable, they improve mechanical properties of the coated material, such as higher hardness and wear resistance and lower friction coefficient. Therefore, the performance of different types of DLC on the anti-corrosion protection of SS was evaluated. Four DLC types were tested: a hydrogenated amorphous DLC; a multilayered film (DLC-M); and films with fluorine (DLC-F) and silicon (DLC-S). The films showed chemical and structural differences, evidenced by Raman, SEM/EDS and XPS analysis. Their tribological performances were evaluated through scuffing resistance tests; the base DLC showed the highest resistance, followed by DLC-F and DLC-M. DLC-S films didn't exhibit satisfactory tribological performance. For corrosion characterization, potentiodynamic polarization tests were conducted in NaCl and CO2-saturated NaCl solutions. In the NaCl tests, DLC films exhibited impressive anti-corrosion properties, with DLC-F delivering the highest performance, followed by DLC-M, DLC-S, and base DLC. 316 L SS showed high corrosion susceptibility in the CO2-saturated solution, but the coatings also improved corrosion resistance in this setting. The DLC, DLC-S and DLC-M showed similar Ecorr and jcorr values, while DLC-F demonstrated superior corrosion resistance with higher Ecorr and lower jcorr values.