Alloy Heat Research Articles

Mechanical and corrosion properties of Al2O3/7075 aluminum matrix composites prepared by additive friction stir deposition

Abstract Additive Friction stir deposition (AFSD) has been extensively utilized for processing Al alloys. The properties of the Al depositions under as-fabricated state, including mechanical strength and corrosion resistance, are typically inferior compared to the base material, especially for heat-treatable alloys. In this research, multilayers of Al7075 composites, reinforced by ceramic particles, were processed by AFSD to evaluate the effect of using feedstock materials containing reinforcing particles on the properties of the deposition. For comparison, a bare Al7075 part was also processed by AFSD under the same conditions. The results of mechanical testing revealed a significant reduction in the microhardness, tensile strength and compression stress of the bare alloy after deposition. However, the composite deposition exhibited only a slight decrease in the properties compared to its feedstock material. Additionally, the corrosion resistance of the composite enhanced after AFSD, in contrast to the bare alloy, where the corrosion resistance deteriorated. Microstructural analysis showed a uniform distribution of the reinforcing particles in the matrix for the deposition, closely resembling that of the feedstock composite. This, along with grain refinement and minimal change in precipitates, were the reasons for the minimum changes in mechanical properties, as well as the improvement in corrosion resistance.

Insight into the corrosion in non-ferrous alloy heat exchangers

Insight into the corrosion in non-ferrous alloy heat exchangers

Influence of Plastic Deformation on the Precipitation Evolution in the Aluminum Alloys in Friction Stir Welding

The influence of temperature on the precipitation evolution in different zones of friction stir welded (FSW) heat-treatable aluminum alloys has been well investigated. However, the role of plastic deformation in affecting precipitation transformations remains less explored. To isolate the contribution of these factors and specifically assess the role of plastic deformation, an approach combining numerical and physical modeling techniques was used. Welding temperature cycles in the FSW weld zones calculated by means of a 3D finite element model were accurately reproduced using a Gleeble instrument. This approach was implemented under two scenarios such as the reproduction of the influence of temperature alone, and the combined effects of temperature and thermally induced plastic strain. The precipitation states and hardness obtained from these controlled experiments were compared to those observed in actual friction stir welds, providing a deeper understanding of the influence mechanisms at play. The results revealed that deformation significantly influences precipitation formation in the stir zone of both 2024 and 6082 alloys, with this effect extending to the heat-affected zone in the case of the 2024 alloy.

A comparative review of machinability in AA2XXX and AA7XXX heat-treatable aluminum alloys: Focus on AA7050-T7451 and AA2050-T84

Heat-treated AA7050-T7451 with high fatigue strength and corrosion cracking resistance, which is frequently used in the aerospace industry, and third generation AA2050-T84 with low density, high fracture toughness, and high hardness strength is distorted due to high chip removal volumes during machining. During machining, depending on the cutting parameters, the cutting forces and high heat transfer during machining cause residual stresses to accumulate on the bulk material. Residual stresses are one of the main causes of distortion theory and one of the most important factors that increase the scrap rate in the machining industry. The observation of a higher risk of distortion in high-volume removal processes such as turning, drilling, milling, etc. has led to the optimization of cutting parameters with a view to reduce the residual stress. In AA7050-T7451 and AA2050-T84, high cutting forces and heat transfer movements vary depending on the material microstructure as well as the spindle speed, feed, cutting type, and cutting tool parameters. The aim of this review is to examine the microstructures and the causes of distortion during the milling of Al alloys, especially AA7050-T7451 and AA2050-T84 for using the aerostructures. The distortions during machining are influenced by the microstructure of the materials, the type of cutter due to chemical reactions, and the cutting parameters due to the heat and cutting forces generated. It can be observed and improved by machining variables such as chip morphology, cutting force analysis, and surface roughness. The effect of cutting parameters such as spindle speed, feed rate, and cutting speed on the distortion of AA7050-T7451 and AA2050-T84 are investigated. As a result, cutting parameters have a crucial effect on the residual stresses in AA7050-T7451 and AA2050-T84 materials.

Sensitization of 5xxx Series Aluminum Alloys explored with an adapted JMAK model for phase evolution and ultrasonics

Abstract Phase transformations in 5xxx series aluminum alloys (AA) during sensitization impact the propagation of ultrasound through these materials in a quantifiable way. The effect of phase evolution on three experimentally measured acoustic parameters (longitudinal wave speed, shear wave speed, and longitudinal wave attenuation) in sensitized 5xxx AA was analyzed under the framework of the Johnson-Mehl-Avrami-Kolmogorov model. The phase transformation rate constant, k, and the Avrami exponent, n, were determined from fitting the experimental data with a developed model. At saturation, which is independent of k and n, the wave speed values agree with those measured individually for each phase. The k value for shear speed is higher for AA5456 than for AA5083, reflecting that AA5456 reaches full sensitization earlier (per standard, the amount of Mg is higher is 5456 than in 5083). The k values for both shear and longitudinal wave speed match the Arrhenius equation for literature NAMLT data (for a given alloy type and heat treatment), the current data extending the existing range to higher temperatures. The difference between the effective k values obtained from the longitudinal-wave attenuation-coefficient and wave-speed data reflects the important contribution of scattering to acoustic attenuation in a sensitized material. The values of n in the 1 to 2 range indicate a combination of 1D and 2D growth, pointing to beta phase growth mostly at grain boundaries and at their intersections. At the highest processing temperature, n is higher, suggesting partial occurrence of 3D growth.

Molding Quality and Biological Evaluation of a Two-Stage Titanium Alloy Dental Implant Based on Combined 3D Printing and Subtracting Manufacturing.

Metal 3D printing has been used in the manufacturing of dental implants. Its technical advantages include high material utilization and the capacity to form arbitrarily complex structures. However, 3D printing alone is insufficient for manufacturing two-stage titanium implants due to the limited precision in printing titanium alloy parts. In this study, 3D printing was employed to create the implant structure, subsequently complemented by mechanical processing to refine the implant abutment connection and neck. Additionally, the mechanical properties of 3D-printed titanium alloy implants were evaluated through tensile and dynamic fatigue testing. The MTT assay was employed to assess the cytotoxicity of 3D-printed titanium alloy dental implants. The impact of bone union and osteogenesis from 3D-printed titanium alloy dental implants was investigated through in vivo experimentation. The results demonstrated that combining 3D printing with subsequent machining constitutes a viable method for the manufacture of two-stage titanium dental implants. Test results for mechanical properties indicated that heat-treated 3D-printed titanium alloy dental implants possess significant tensile strength and fatigue resistance and are capable of withstanding the robust chewing forces in the oral cavity. In vitro findings revealed that sandblasted and acid-etched 3D-printed titanium alloy exhibited negligible cytotoxicity, with osteoblast differentiation of hMSCs being more pronounced compared with the control group. In vivo studies indicated that no significant differences were observed in bone volume fraction, bone-implant contact rate, and unscrewing torque between 3D-printed titanium alloy dental implants and commercial SLA surface implants at both 1 and 3 months postimplantation.

Alloy Element Adjustment and Heat Treatment Combination in Enhancing Electromagnetic Wave Absorption Properties of FeCoNiCu Medium Entropy Alloy

Alloy Element Adjustment and Heat Treatment Combination in Enhancing Electromagnetic Wave Absorption Properties of FeCoNiCu Medium Entropy Alloy

Modification of mechanical and microstructural characteristics into Ti‐6Al‐4V alloy by thermal treatment

Purpose The purpose of this study is to analyze the titanium alloy under heat treated condition. Titanium alloy heat treatment, particularly Ti‐6Al‐4V alloy, has been an important field of study due to its wide variety of uses in the aerospace, automotive, and biomedical sectors. The mechanical characteristics of titanium alloys are heavily influenced by their microstructure. Cold‐rolled Ti‐alloys have strong bending and tensile strength due to extensive β‐phase precipitation on the α matrix. However, various heat treatment (HT) methods can affect the mechanical characteristics. The current study seeks to investigate the effects of various heat treatment procedures on the microstructural and mechanical changes of Ti‐6Al‐4V alloy, in order to achieve an optimal balance of strength, hardness, and ductility for a variety of real-world applications. Design/methodology/approach Three plates of Ti‐6Al‐4V alloy were heated above the β‐transus temperature for a certain period and then cooled via furnace, air, and sand. One extra plate was kept in ‘untreated’ condition and given name ‘as received’ plate. The three heat treated plates were evaluated and compared with ‘as received’ plate based on tensile strength, bending strength, hardness, and microstructural changes. Findings A considerable change in orientation of α and β was noted through optical microscopy upon heat treatment. The mechanical testing revealed that all the cooling methods adopted in the study have reduced the UTS and increased the YS of the plates. The ductility of the alloy was primarily enhanced by 'air cooling' and 'sand cooling' methods. Originality/value Notably, the hardness test findings indicated a significant drop in hardness for the ‘sand‐cooled’ sample. Furthermore, the ‘air cooled’ sample showed the maximum hardness due to the production of acicular α regions.

Expanding the Applications of Copper-based Alloys by Thermal Arc Spraying

In this article, the case of depositing a Ni-based alloy layer by thermal arc spraying on a copper alloy substrate with cylindrical geometry over its entire surface is presented. After the coating was deposited, the layer was analyzed microstructurally both on the surface and in cross-section, and it was observed that it adhered very well to the substrate. In addition to the high adhesion to the substrate, a low porosity of the coating was observed, which ensures good compactness of the coating. Based on these results, further investigation of the Ni coating can be recommended to limit the toxicity caused by the oxidation of copper and copper alloy heating elements.

Thermophysical properties of undercooled Zr–Fe–Nb alloys investigated by electrostatic levitation and molecular dynamics calculation

The density, surface tension, and viscosity of liquid Zr76.0−xFe24.0Nbx (x = 6.6, 10.0, 15.0) alloys were measured by using the electrostatic levitation technique. The maximum undercooling achieved for these alloys was 151, 91, and 119 K, respectively. To evaluate the thermophysical properties in a wider temperature range, molecular dynamics simulations were performed by using the embedded atom method potential. Both measured and simulated results indicate that the liquid density increases linearly with decreasing temperature and also gradually rises with increasing Nb content. Additionally, the simulated and experimental results for surface tension and viscosity were analyzed. In all three alloys, surface tension increases linearly with decreasing temperature. The relationship between viscosity and temperature follows an Arrhenius-type equation, with both surface tension and viscosity increasing as the Nb content increases. The calculated results of density, surface tension, and viscosity are in good agreement with the experimental results. Furthermore, the specific heat, emissivity, and diffusion coefficient of liquid alloys were calculated. The specific heat for liquid Zr76.0−xFe24.0Nbx (x = 6.6, 10.0, 15.0) alloys is (36.47 ± 1.68), (35.20 ± 2.28), and (41.04 ± 3.73) J mol−1 K−1, respectively. Emissivity decreases linearly with temperature. The diffusion coefficient decreases, while the diffusion activation energy increases with a higher Nb content.

The study on the effect of preliminary heat treatment of Nd2Fe14B magnetic alloys from spent hard drives on the performance of the hydrogen decrepitation process

The study on the effect of preliminary heat treatment of Nd2Fe14B magnetic alloys from spent hard drives on the performance of the hydrogen decrepitation process

High Strain Rate Deformation of Heat-Treated AA2519 Alloy.

This study examined the effects of heat treatment on the microstructure and dynamic deformation characteristics of AA2519 aluminum alloy in T4, T6, and T8 tempers under high strain rates of 1000-4000 s-1. A Split Hopkinson pressure bar (SHPB) was utilized to characterize the mechanical response, and microstructural analysis was performed to examine the material's microstructure. The findings indicated varied deformation across all three temper conditions. The dynamic behavior of each temper is influenced by its strength properties, which are determined by the aging type and the subsequent transformation of strengthening precipitates, along with the initial microstructure. At a strain rate of 1500 s-1, AA2519-T6 demonstrated a peak dynamic yield strength of 509 MPa and a flow stress of 667 MPa. These values are comparable to those recorded for AA2519-T8 at a strain rate of 3500 s-1. AA2519-T4 exhibited the lowest strength and flow stress characteristics. The T6 temper demonstrated initial stress collapse, dynamic strain aging, and an increased tendency for shear band formation and fracture within the defined strain rate range. The strain rates all showed similar trends in terms of strain hardening rate. The damage evolution of the alloy primarily involved the nucleation, shearing, and cracking of dispersoid particles.

Advances in Heat Treatment and Microstructural Optimization of Hadfield Steel for Enhanced Wear Resistance

Objective: This study aims to explore the impact of heat treatment processes on carbide formation in Hadfield steel, focusing on optimizing its microstructure and mechanical properties for industrial applications that require high wear resistance. Theoretical Framework: The research is grounded in theories of metallurgical transformation and work hardening, particularly in relation to the metastable austenitic structure of Hadfield steel, which transforms into martensite under impact. This transformation mechanism, alongside alloy composition and heat treatment, shapes the steel’s resistance to wear and mechanical strength. Method: A systematic literature review was conducted, encompassing 11 relevant studies on Hadfield steel from four scientific databases: Taylor & Francis, Springer, Wiley, and ScienceDirect. The selected studies were analyzed using the PRISMA methodology to evaluate the influence of heat treatments—such as austenitization, quenching, and tempering—on carbide formation and microstructure. Results and Discussion: Findings reveal that specific heat treatments significantly enhance Hadfield steel’s wear resistance and strength. The influence of processes like austenitization on carbide dissolution and rapid cooling to avoid carbide precipitation has proven critical for the steel’s toughness. This discussion aligns the observed improvements with theoretical predictions and identifies challenges in carbide control for enhanced performance. Research Implications: The study provides practical insights for industries utilizing Hadfield steel in high-wear environments, such as mining and transportation, and proposes further research into innovative heat treatment strategies. Originality/Value: This study contributes novel perspectives on the optimization of Hadfield steel's heat treatment processes, potentially informing advanced manufacturing techniques to improve the steel’s durability and economic value in key industrial applications.

Investigation of tribological properties of heat-treated ZrNbTiVAl high entropy alloy in dry sliding conditions

This study explored the relationship between tribological performance and microstructural changes induced by heat treatment in a newly developed ZrNbTiVAl high-entropy alloy (HEA). The alloy was evaluated in its as-cast state and after heat treatments at 950 °C for 15, 20, and 25 h, with dry sliding experiments conducted against an alumina ball counterface. Advanced analytical techniques, including 3D optical profilometry, nanohardness testing, field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), and Micro-Raman spectroscopy, were employed for comprehensive surface analysis and to investigate oxide layer formation on the worn surfaces.The study reveals a nuanced relationship between heat treatment duration, oxide layer formation, and frictional behavior in the ZrNbTiVAl high-entropy alloy (HEA). Increasing the heat treatment duration at 950 °C results in higher hardness (H) and a reduction in the modulus of elasticity (E) of the ZrNbTiVAl high-entropy alloy (HEA). Notably, wear rate and friction were lower in the as-cast and 15 h heat-treated conditions, despite their lower H/E and H³/E2 values compared to the 20 h and 25 h heat-treated states. Additionally, the wear mechanisms shift significantly, from mild adhesive/oxidative wear in the as-cast and 15 h conditions to severe adhesive/oxidative wear in the 20 h and 25 h conditions. This improved performance in the as-cast and 15 h conditions is attributed to the enrichment of Ti and V—elements recognized for their solid lubrication properties—and a reduced presence of Al-Zr intermetallics, which helps to minimize the formation of hard wear debris during dry sliding. These findings underscore the importance of optimizing heat treatment parameters to achieve superior tribological performance.

Effectiveness and efficiency of tool alignment and simultaneity factors on double-sided friction stir welding for joining heat-treatable aluminum alloys: a review

Effectiveness and efficiency of tool alignment and simultaneity factors on double-sided friction stir welding for joining heat-treatable aluminum alloys: a review

Homogenization Heat Treatment of CoCrCuMnNi High-Entropy Alloys: Limitations and Challenges

Homogenization Heat Treatment of CoCrCuMnNi High-Entropy Alloys: Limitations and Challenges

Geothermo-mechanical energy conversion using shape memory alloy heat engine

The shift towards renewable energy sources like geothermal energy has become desirable due to the recurrent energy crisis and global warming challenges influenced by fossil fuels. Geothermo-mechanical energy conversion using shape memory alloy (SMA) heat engines presents a novel and sustainable approach for harnessing geothermal energy. Shape memory alloys, known for their ability to undergo reversible phase transformations driven by temperature changes, are ideal for thermal-to-mechanical energy conversion. This paper explores the design and performance of an SMA heat engine that utilizes geothermal heat sources to drive mechanical work. The engine operates by cycling between the high-temperature geothermal environment and a cooler sink, exploiting the shape memory effect to generate mechanical motion. By integrating geothermal energy and SMA technology, this system offers a potential solution for renewable energy generation, with applications in remote or off-grid locations. The paper also investigates output power and the thermodynamic efficiency. A model is formulated and the engine behavior is simulated. A series of experiments are conducted for engine output power and efficiency. The model is compared to the experimental data for validation. The engine developed a maximum power of 3.5, 8.5, and 11.5 watts at 60, 80, and 90 °C respectively. The proposed SMA-based geothermo-mechanical energy conversion system offers a promising solution for efficient, reliable, and scalable geothermal energy harvesting. This research contributes to the development of innovative, efficient geothermal energy conversion technologies, supporting global renewable energy goals and reducing greenhouse gas emissions. This innovative energy conversion mechanism could play a key role in the future of sustainable power generation.

An aging processing design scheme derived from precipitation thermo-kinetic synergy of heat-treatable aluminum alloys

Determination of ideal aging processing is crucial for developing heat-treatable aluminum (Al) alloys with good mechanical performances. To make full use of the advantages of precipitation, in the present work, we firstly established a yield strength model from the perspective of thermo-kinetic synergy. Then, we proposed a two-steps scheme to design the aging processing of the heat-treatable Al alloys. By taken the 6xxx Al alloys as representatives, in the first-step, the optimal aging time (tp) at a given temperature, which derives from a high energy barrier for β” precipitation, is determined from the plateau endpoint of system energy dissipation curve. In the second-step, the optimal aging temperature (TA), which originates from a large driving force for β” precipitation, is determined as the transition point from the Guinier-Preston (GP) zones to the β” phase. The rationality of this scheme was verified via the model system of Al-1.0Mg-0.6Si alloy, the precipitation behaviors of which have been well studied. Finally, we applied this scheme to the Al-0.46Mg-1.04Si alloy, whose optimal aging processing parameters are determined as TA = 438 K and tp = 9.37 h. Subsequent parallel experiments confirmed that the alloy samples aged at this pre-designed aging processing condition behaves the highest yield strength of σy = 279.20 MPa, agreeing well with the predicted value of 275.80 MPa from the present strength model. We further extended the applications to the 2xxx Al alloys. The predicted ideal aging processing parameters (3.50 h at 438 K) and the according yield strength (399.57 MPa) for the Al-4.62Cu alloy are in accordance with the experimental results. Our investigation provides an insightful guidance for designing the advanced Al alloys with high strength from the perspective of precipitation thermo-kinetic synergy.

Enhanced heavy oil fouling resistance of cobalt-based spray-deposited coatings by alloy design and heat treatment

Heavy oil hydrocracking fouls critical reactor components, causing premature turnarounds. Developing materials with superior resistance to coking, sulfidation, and wear proves crucial. High-velocity oxy-fuel (HVOF) coating improves materials' properties as an industrial-ready solution. This study explores the effect of alloying elements on the HVOF-sprayed Co-Cr-Mo-Si coating model and their role in protecting against heavy oil fouling. Heat treatment reduced the coatings' inhomogeneity and microstructural defects, substantially improving their protection against fouling. A novel optical image treatment has been developed to semi-quantitatively assess the surface fouling intensity. The study provides insights into the complex interplay between alloy composition, microstructure, heat treatment, and surface energy in optimizing coating protection against heavy oil fouling.

Creep Lifetime Prediction of Alloy 617 Using Black Box Machine Learning Approach

Abstract This study explored the application of black box machine learning (ML) to build high throughput models that predict the creep response of Ni-based Alloy 617. Black box ML refers to highly complex machine learning algorithms that generate outputs from inputs without an interpretable internal process. The rapid implementation of suitable heat of alloys into targeted service is impeded by the extended qualification process involving chemistry-processing-structure-performance assessment. The ASME B&PV Code III outlines the requirement of 10,000 h of creep testing before each heat can be qualified for service and 30,000 h for heats that exhibit metastable phases. There is a critical need to shorten the development-to-deployment timeline for heats of an alloy at specific applications. Recent advancement in ML offers the ability to identify correlations in data which is difficult to elucidate by other approaches. To that end, black box ML is employed to expedite the HEAT qualification of Alloy 617 and predict performance from HEAT chemistry out to an unprecedented timescale. In this study, creep data for Ni-based Alloy 617—a solid solution strengthened material is gathered from a wide range of data sources. The alloy chemistry, phases, precipitates, and microstructural features are analyzed to obtain the key strengthening mechanism. Service conditions, mechanical properties, chemistry, and chemical ratios are provided as potential input features. The Pearson correlation coefficient with a 95% confidence bound is employed for input feature screening where poorly correlated inputs are eliminated to speed up the ML process and prevent under- and/or over-fitting of predictions. In the ML algorithm, the selected input features are regarded as predictors, and rupture is regarded as the response. An algorithm evaluation is performed where 20 ML algorithms are trained with the training set. The three-layered neural network (NN) was observed to be the best algorithm for the given data based on statistical rationale. The NN accurately predicts rupture across a range of isotherms and data sources. The interpolative and extrapolative predictions are in compliance with ECCC V5 guidelines. A post-audit validation exhibits neither under- nor over-fitting and confirms the applicability of NN algorithms to unseen data. The black box ML provides a pathway to predict the performance directly from chemistry and opens avenues to rapid heat qualification.