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The history of antimony modification of Al–Si casting alloys is reviewed, together with the important technical and commercial reasons why antimony is no longer used as a modifier. [ABSTRACT FROM AUTHOR]

As a destructive phenomenon with possible detrimental impact especially when it comes to human life, tribocorrosion has always been imperative to be researched. Hence, various investigations have outlined its influential role in the biomaterial apparatuses. Also, disparate routes have been introduced to address this problem. The use of several types of alloys, the application of various types of coatings, and the production of porous layers are some of these efforts made till now. Because of this issue's importance, and lack of a comprehensive review paper in this area of research, this paper shows an overview of existing publications in this area of research. This study presents the important ideas behind studies and provides a perspective of the research trend. In this exploration, the critical elements of the tribocorrosion-related studies were discussed thoroughly. The origin of the problem and the influential parameters in the process like loading, manufacturing, environment, and surface innate oxide film were scrutinized. Also, the efficacy of the use of different alloys, coatings, and the recommended modifications with respect to the tribocorrosion was discovered. We hope that this survey helps promote the emergence of new ideas for future research. [ABSTRACT FROM AUTHOR]

FeRh-based alloys have attracted significant attention due to their magnetic phase transition and significant magnetocaloric effects. These properties position them as promising candidates for fundamental research and practical applications, including magnetic cooling and targeted drug delivery. The study of FeRh alloys, particularly those where Rhodium or Iron atoms are substituted with other transition metals, is crucial as certain substitutions preserve the alloy's magnetocaloric properties. However, even within a specific structural type and without considering competing phases, determining which atom (Fe or Rh) is replaced upon introducing a third element remains unclear. This paper addresses this ambiguity through ab initio calculations. We propose an approach to predict whether a dopant will replace Fe or Rh, offering insights into the electronic and structural factors influencing the substitution. Additionally, we present a dataset of ab initio calculations on doped FeRh alloys, which will support future data-driven modeling efforts. Our findings not only advance the understanding of FeRh-based alloys but also contribute to the design of novel materials for experimental and industrial applications. [ABSTRACT FROM AUTHOR]

This paper reports on the development and validation of a formal model for an automotive adaptive exterior lights system (ELS) with multiple variants in Alloy 6, which is the most recent version of the Alloy lightweight formal specification language that supports mutable relations and temporal logic. We explore different strategies to address variability, one in pure Alloy and another through an annotative language extension. We then show how Alloy and its Analyzer can be used to validate systems of this nature, namely by checking that the reference scenarios are admissible, and to automatically verify whether the established requirements hold. A prototype was developed to translate the provided validation sequences into Alloy and back to further automate the validation process. The resulting ELS model was validated against the provided validation sequences and verified for most of requirements for all variants. [ABSTRACT FROM AUTHOR]

Integral blisk blades are typical complex curved structures with small thickness, low stiffness, and complex boundaries. Due to the high material removal rate during the machining process, they are prone to force-induced deformation, resulting in significant machining errors. This seriously contradicts the requirements for high design accuracy and surface accuracy in the aerospace industry. Therefore, accurately predicting the distribution pattern of deformation caused by dynamic milling forces during the machining process and proposing reasonable error compensation strategies are urgent issues to be solved in the manufacturing of integral blisk blade. Firstly, this paper establishes a prediction model for the deformation distribution during the milling process of the integral blisk blade. Secondly, based on the finite element deformation prediction model of blades, the selection of blade milling processing methods and parameters was completed with the goal of minimizing machining deformation. Finally, a reverse reconstruction geometric modeling compensation strategy is proposed, and the tool path program containing the deformation error compensation amount is regenerated. The prediction model and compensation strategy proposed in this paper were validated through milling experiments and profile accuracy measurement experiments on a certain aeroengine integral blisk blade. The results showed that the prediction model has high reliability, with an average error of 7.96%; the new compensation strategy can reduce the tool-yielding error to within the tolerance range. This study will provide technical support for improving the machining accuracy and efficiency of integral blisk blade. [ABSTRACT FROM AUTHOR]

Ram Devanathan and Laurent Capolungo are Guest Editors for the ICME Committee of TMS and coordinated the topic on Computational Design of Alloys for Energy Technologies in this issue. The first paper in this topic deals with metal-carbide interfaces that are ubiquitous in alloys and play a crucial role in the mechanical properties. Their work, "Data-guided feature identification for predicting specific heat of multicomponent alloys", shows that it is possible to predict alloy properties reliably even from small datasets if high-quality training data are available. [Extracted from the article]

In recent years, the thermal analysis (TA) technique has been widely applied in aluminum foundries to predict alloy composition and microstructural constituents. This technique has been extended to solidification, providing valuable information for simulation experts, such as characteristic solidification temperatures, the amount of fraction solid, and the alloy feeding ability. This paper analyzes the solidification path of two series of hypoeutectic aluminum alloys, AlSi7Cu(1–4) and AlSi9Cu(1–4), applying differential scanning calorimetry (DSC) and TA techniques. The alloys latent heat (LH) was measured with a DSC apparatus at a cooling rate of 10 °C min−1. The cooling curve was analyzed to calculate the amount of fraction solid and LH released at 10 °C min−1 cooling rate. The Newtonian technique of zero curves was used to establish a baseline and calculate the amount of fraction solid and its LH. The LH calculated by the TA method was compared with the measured values gained by applying DSC and with the calculated LH values obtained by applying the market-available JMatPro software package. The aim of the paper is to show the possibility of determining LH using the TA technique. [ABSTRACT FROM AUTHOR]

Background: Mini-screws are widely used as temporary anchorages in orthodontic treatment, but have the disadvantage of showing a high failure rate of about 10%. Therefore, orthodontic mini-screws should have high biocompatibility and retention. Previous studies have demonstrated that the retention of mini-screws can be improved by imparting bioactivity to the surface. The method for imparting bioactivity proposed in this paper is to sequentially perform anodization, periodic pre-calcification, and heat treatments with a Ti–6Al–4V ELI alloy mini-screw. Materials and methods: A TiO2 nanotube-structured layer was formed on the surface of the Ti–6Al–4V ELI alloy mini-screw through anodization in which a voltage of 20 V was applied to a glycerol solution containing 20 wt% H2O and 1.4 wt% NH4F for 60 min. Fine granular calcium phosphate precipitates of HA and octacalcium phosphate were generated as clusters on the surface through the cyclic pre-calcification and heat treatments. The cyclic pre-calcification treatment is a process of immersion in a 0.05 M NaH2PO4 solution and a saturated Ca(OH)2 solution at 90 °C for 1 min each. Results: It was confirmed that the densely structured protrusions were precipitated, and Ca and P concentrations, which bind and concentrate endogenous bone morphogenetic proteins, increased on the surface after simulated body fluid (SBF) immersion test. In addition, the removal torque of the mini-screw fixed into rabbit tibias for 4 weeks was measured to be 8.70 ± 2.60 N cm. Conclusions: A noteworthy point in this paper is that the Ca and P concentrations, which provide a scaffold suitable for endogenous bone formation, further increased over time after SBF immersion of the APH group specimens. The other point is that our mini-screws have a significantly higher removal torque compared to untreated mini-screws. These results represent that the mini-screw proposed in this paper can be used as a mini-screw for orthodontics. [ABSTRACT FROM AUTHOR]

This study concentrates on comparing effects of conventional and laser-assisted machining (LAM) of laser-borided Monel 400 alloy. For this purpose, the shaft made from Monel 400 was covered with 200-µm thick boron layer and surface melted using diode laser. For determining the influence of laser beam scanning velocity on final microstructure, microhardness, and depth of melting, four laser beam scanning velocities were set: 5, 6, 8. and 10 m/min. Obtained microstructures are typical for laser-melted metal and are composed of fine crystals. Microhardness increased significantly due to enriching Monel 400 with boron and the level of this increase depends on the laser beam scanning velocity carried out for the process. During both conventional and laser-assisted turning, cutting forces were measured for comparison. Other compared parameters after carrying out these processes were obtained surface roughness and tool life. It was found that it is possible to form laser-borided surface of Monel 400 alloy by machining and using additional laser-assist has a positive impact on the efficiency of the process. Laser-assisted machining allows to lower cutting forces during machining and this leads to extended tool life. On the other hand, this method provides lower values of roughness parameters on the machined surface due to the effect of softening the surface during the process. The paper is the first description of effects obtained by laser-assisted machining of laser-borided surface. [ABSTRACT FROM AUTHOR]

Ti6Al4V alloy is one of the typical difficult-to-machine materials and often results in rapid tool wear, leading to poor machining quality in aircraft assembling. Compared to conventional helical milling, the ultrasonic assistant helical milling (UAHM) process has indicated its superior performance; however, it is still a great challenge to improve the hole surface quality and accuracy. In addition, few studies have been conducted on the effect of different variables and cooling strategies on the hole-making performance in longitudinal-torsional ultrasonic assisted helical milling (LT-UAHM). This paper, for the first time, reports effects of machining variables on geometric precision and surface roughness in LT-UAHM of Ti6Al4V. In addition, the lubrication/cooling mechanism on the simultaneous application of LT-UAHM and MQL is theoretically analyzed. The design approach of Taguchi experiment was employed to study how major variables such as the cutting speed, tangential feed, axial feed, and the workpiece hardness influence the dimensional and geometrical tolerances and surface roughness. This paper also discussed the effect of three cooling strategies, i.e., dry condition, air coolant, and minimum quantity lubrication (MQL) in LT-UAHM. Theoretical analysis demonstrated that the MQL coolant can be nebulized into hyper-fine droplets owing to the resonant cavitation phenomenon. Combined with the penetrating action caused by the separate-cutting principles of LT-UAHM, the cooling and lubrication performance of MQL was further enhanced. As a result, LT-UAHM with MQL had the most positive effect on circularity, cylindricity, nominal diameter, and surface roughness, contributing to 34%, 32%, 39%, and 40%, respectively. The second important machining factor was the cutting speed, contributing to 31%, 29%, 36%, and 22%, respectively. The tangential feed and workpiece hardness have the negative effect on geometrical accuracy, respectively. [ABSTRACT FROM AUTHOR]

Within microservice architecture-based systems, some microservices are integrated to build the software. The integration of these services may be defined based on a workflow model. There are also a variety of different languages available for defining these workflow models. BPMN and YAWL are two such options. It is important that testers test the integration of these microservices. This paper proposes the formal method as the solution for integration testing. This method translates the workflow model to the Alloy. The algorithm has suggested a translation of workflow models to formal specifications. This specification takes into consideration both structural and behavioral aspects. The first perspective is about general structures, while the second is about the behavior of the objects in a specific model. We have proved the correctness of the suggested specifications. For this purpose, the paper has shown that formal definitions are sound and are complete with nine theorems for these properties. The translation from YAWL to Alloy is defined based on their BNF grammar. The generated model is an appropriate source for different purposes containing software testing. The suggested method for software testing is model-driven testing. Logical predicates define the structure of Alloy models. This method uses these logical predicates for generating tests. The test method has used RACC coverage as an example criterion. Alloy Analyzer tests the model by generating test predicates. [ABSTRACT FROM AUTHOR]

In recent years, more attention to unique and complex structures, such as nature-inspired and porous structures for medical applications, has been strongly developed. Open-cell porous metal-based ones display more benefits than rigid ones since they facilitate the transformation of load between the bone and the implants and avoid the phenomenon of stress shielding and bone resorption. By being biodegradable and non-toxic, as well as having lower density and mechanical properties close to those of natural bone, Mg and its alloys are considered promising materials for porous scaffolds. However, a high corrosion rate is the main drawback of Mg alloys. The porosity of porous structures can also worsen it as it enhances the surface area exposed to the corrosive solution and negatively impacts the performance of porous structures, that these issues have not been addressed in detail so far. Since fabrication methods of Mg-based scaffolds can significantly affect the porosity-related properties (e.g., porosity percentage, type, size, and geometry) and, consequently, scaffolds' mechanical behavior and corrosion resistance, this paper reviews and compares the fabrication methods of porous structures and how they affect the resultant properties. However, among different methods, due to the expansion of additive manufacturing as a novel and exciting manufacturing technique, the paper's central focus is on using additive manufacturing in biomedical applications, discussing its advantages over other techniques. The effect of geometrical parameters on mechanical properties and corrosion rate, which strongly affects bio-application, are also given. Moreover, different strategies are briefly introduced for tailoring the high corrosion rate of Mg and its alloys, such as alloying elements and coatings. However, there is still less information regarding the additive manufacturing of porous Mg scaffolds and the optimum way of controlling the corrosion rate of Mg-based parts. [ABSTRACT FROM AUTHOR]

Si–Ge–Sn alloys are offering unusual material properties with a strong potential to add a variety of functionalities to advanced CMOS technology. Being a group IV alloy, SiGeSn can be monolithically integrated on Si. The discovery of a direct band gap at Sn concentration above 8%, the extremely small effective mass for electrons and holes as well as the pronounced phonon scattering are opening new opportunities for Si photonics, high frequency devices and thermoelectrics. Si–Ge–Sn alloys with Sn concentration far beyond the solid solubility limit are metastable, artificial materials, which request challenging growth conditions. In this paper the epitaxial conditions for Si–Ge–Sn alloys to achieve precise control of the Sn content, to manage the lattice mismatch and defects, as well as to fabricate doped layers are discussed. The applied process control allows for epitaxy of group-IV heterostructures, required for typical devices for photonic and electronic applications. In this context, lasers and nanowires MOSFETs are discussed in this paper. In additions, the thermal conductivity is investigated as a critical material parameter to obtain a high thermoelectric figure of merit in GeSn alloys. [ABSTRACT FROM AUTHOR]

Biodegradable materials like magnesium-based alloys are widely employed for making implants. Mg-based alloys show good biocompatibility, biodegradability, and mechanical properties similar to bone material unlike other commonly used implant materials, i.e., stainless steel, titanium, and Co–Cr alloy, which have negligible degradation rates and require revision surgery for the removal of the implant. Magnesium alloy-based implant has high degradation rates and avoids the need for a second surgery. But high degradation rates and poor mechanical properties in magnesium alloys also pose a challenge to their use as implant material. In the absence of controlled degradation, they can degrade completely before serving their intended purpose in the human body. Several surface modification techniques are used to control the degradation rates. Surface coating is one of the methods of surface modification. This paper discusses various types of surface coating techniques for magnesium-based alloys. This paper also discusses the future scope of surface technology of magnesium-based implant materials. [ABSTRACT FROM AUTHOR]

Grain-boundary diffusion affects composition profiles developed during selective oxidation in polycrystals. It is therefore desirable to consider the grain size when choosing an alloy or setting acceptable operating conditions for an application where high-temperature corrosion resistance is important. This paper aims to provide guidelines to evaluate subsurface composition changes as a function of grain size and oxidation conditions. We show that depletion profiles around isolated grain boundaries of Ni-based Cr2O3-forming alloys oxidized at 1000 ∘ C can be described by a 2D diffusion model, where fast diffusion at the alloy–scale interface is considered in addition to grain-boundary diffusion. We then illustrate the general features of depletion profiles in polycrystals, in comparison with single crystals. Finally, we use a set of simulations covering a wide range of times, temperatures and grain sizes to identify regimes where a 1D model can be used, either because grain-boundary diffusion can be neglected or because it produces a uniform depletion front. [ABSTRACT FROM AUTHOR]

A novel multi-directional eddy current thermography (ECT) system is presented generating sets of directional phase images that have been fused with a processing pipeline allowing for an improved probability of detection (POD). Inhomogeneous electromagnetic Joule heating derived from the diversion of induced eddy currents provoked by cracks, altering its path around as well as under its bottom, is the principal phenomenon enabling its usage as a non-destructive-evaluation (NDE) technique. Most induction thermography systems employ inductors derived from old designs, optimized for localized heating with a fixed magnetic field direction. This provokes a directional detection blind-spot for surfaces with random crack orientations. In this paper we have observed that the pattern associated with the thermal response distribution can be geometrically correlated to the relative orientation of the magnetic field regarding the crack, conforming to a rotating feature that has not been described before. Extracting the apparent motion as an optical flow, with a phase-shifting interpolation of the intermediate orientations, generates a signal that enables a robust segmentation of a wide variety of defects in ferritic and austenitic alloys. Its performance has been evaluated with two 'Hit/Miss' POD studies TIG welds Inconel 718 and Haynes 282 alloys. Results show an increased detectability regarding the manual labelling of the defects in the same directional set, employing the same input. [ABSTRACT FROM AUTHOR]

Here we use phase field to model and simulate "hopper" crystals, so named because of their underlying cubic structure but with a hopper-like depression on each of the six faces. Over the past three decades simulations of single phase solidification have successfully explored dendritic structures, in two and three dimensions, formed under high undercooling from a slight perturbation in anisotropy. More recently we see the modelling of faceted structures at near equilibrium, and also, under high undercooling, the formation of dendritic-like structures in two dimensions which retain some faceting in the dendrite arms. A cubic hopper crystal appears to be a hybrid structure, somewhere between a perfect cube and a dendrite, and, to date, has not appeared in the modelling literature. In this paper we describe a model for faceted cubic growth and explore results, necessarily in three dimensions, that include perfect cube, hopper and dendritic. We also touch briefly on one other morphology—octahedral. [ABSTRACT FROM AUTHOR]

Topologically close-packed (TCP) phases such as Laves phases are usually considered to harm the mechanical properties of classical superalloys for high-temperature applications. However, if an optimal fraction and size are designed, this situation can completely change for some compositionally complex alloys (CCA). Based on existing studies on austenitic or ferritic steels, we propose in this paper a design strategy aimed at exploiting the role of the Laves phase in defining the mechanical properties of wrought CCAs at elevated temperatures. We demonstrate its efficiency by applying it to the design and production of a new Laves phase—reinforced CCA and present the results of their experimental and theoretical investigation. The results show that a new Laves phase-reinforced CCA can have fine-grained microstructures, lower density, and superior mechanical strength at elevated temperatures while maintaining workability. These new alloys show promising properties compared to existing CCA wrought alloys and actual Ni-based superalloys. [ABSTRACT FROM AUTHOR]

The cracking of nickel-based single-crystal alloys is associated with the residual stress. In this paper, we employed focused ion beam and digital image correlation (FIB-DIC) technology to characterize the crack-tip residual stress at ultrahigh spatial resolution. The repeatability and accuracy of FIB-DIC were validated by experiments and simulations. A direct correlation between residual stress and hardness was established, which provides a new way to prevent cracking through the visualization and control of residual stress. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to investigate the effect of Zr and its synergistic effect together with the addition of an inoculant (Ti) and a modifier (Sr) in terms of structural analysis and mechanical characteristics of AlSi7Mg0.3Cu0.5 alloy. In accordance with the objectives of the paper, in the experimental part, eight material variants were cast by the investment casting method. The presence of Zr in the experimental alloys was manifested by the crystallization of phases with different chemical compositions mainly (AlSi)3(TiZr) and (AlSi)2(TiZr). The graded addition of Ti in the alloys resulted in a higher number of nucleation grains of Zr-rich phases, and alloys with a combination of Zr and Sr were characterized by the formation of (AlSi)2(TiZr) phases. Various types of precipitates based on Zr (Al3(ZrTi)) and Cu (Al2Cu) were observed in the substructure of the alloys. The addition of Zr and its synergistic effect with Ti and Sr led to an increase in the conventional yield strength, hardness and partly tensile strength with reduced elongation of the experimental alloys. [ABSTRACT FROM AUTHOR]

Blast furnace ironmaking produces a reducing and carburizing atmosphere in the blast furnace which may lead to metal dusting. However, there is limited research on metal dusting under this particular atmosphere. This paper investigated metal dusting behaviors of ferritic Fe-(10, 20, 25)Cr and austenitic Fe-20Cr-(20, 33)Ni, Fe-25Cr-20Ni (wt.%) alloys at 550 and 650 °C in an Ar-33CO-7H2-7CO2-2H2O (vol.%) gas simulating a blast furnace operating condition. A relatively short reaction time, up to 100 h, was used to evaluate the initial stage of metal dusting of these alloys in the blast furnace gas condition. Severe metal dusting and coke deposition were observed at 550 °C, while no significant dusting but internal oxidation and carburization were observed at 650 °C. Higher Cr and Ni contents in the alloy lowered kinetics of metal dusting at 550 °C and of carburization at both temperatures. Austenitic alloys were more susceptible to metal dusting and coke deposition than ferritic alloys with the same Cr content at 550 °C. At 650 °C, however, ferritic alloys experienced higher extents of carburization and oxidation than austenitic alloys with the same Cr concentration. The effects of alloy composition and reaction temperature on metal dusting in this simulated blast furnace operating condition were discussed. [ABSTRACT FROM AUTHOR]

Benjamin Adam is the Guest Editor for the TMS High Temperature Alloys Committee and organized the topic High Temperature Alloys: Manufacturing, Processing, and Repair in the August and September 2022 issues of JOM. This I JOM i topic is sponsored by the High-Temperature Alloys Committee of TMS and addresses advances in the manufacturing and processing of high-temperature alloys. Finally, in 2022, a symposium will be organized for the Materials Science and Technology Conference in Pittsburgh, PA on October 9-13: "Alloy Phase transformations at elevated temperature alloys". [Extracted from the article]

The mechanical properties possessed by surface layers of metal alloys hardened by severe plastic deformation methods were studied by indentation. The test materials were AISI O2 and AISI 316L steels and D16 aluminum alloy. Most scientific papers evaluate the mechanical properties of hardened surface layers and thin coatings only by hardness measurement. Hardness alone cannot characterize the ductility of a material without using modern concepts for determining the physical ductility from hardness. The mechanical behavior of a material can only be characterized by determining both the ductility and the yield stress. These quantities can be found by micro- or nanoindentation. We developed indentation methods to find the physical ductility δH and yield stress σSH of the surface layers of metal alloys hardened by various techniques (with analysis of changes in these characteristics across the hardened layer) to select the optimal hardening method. The hardening characterized by the ratio between the yield stresses of the hardened layer and the starting material σ SH hard / σ SH start was much greater for all studied alloys than the hardening characterized by the hardness ratio (HVhard/HVstart). Thus, the use of δH and σSH obtained from standard microhardness measurements enhanced the informative nature and efficiency of the indentation method in studying the mechanical behavior of metal alloy layers hardened by various techniques. [ABSTRACT FROM AUTHOR]

In this paper, we draw attention to the investigation of the novel exact solution [1.Scripta Mat. 210:114430; M.A. Dayananda, in JPED, this issue, (2022);] that is applicable to a multicomponent (n-component) interdiffusion couple where the interdiffusion matrix may change with alloy composition. In the derivation of this solution the interdiffusion flux J j of a component j is related to (n-1) independent composition gradients for an isothermal, diffusion couple using the well-known continuity equation. Novel exact expressions are then derived for all of the interdiffusion coefficients, D ~ ij n (i, j = 1, 2, .....n − 1), where the partial derivatives of the product J j y - y 0 with respect to composition C i ( y 0 is the Matano plane) are used. In this paper, it is shown that the novel solution leads to a computational procedure similar to the Boltzmann-Matano analysis. Note that the derivatives ∂ (J j y - y 0 ) / ∂ C i , i , j = 1 , ... , n - 1 (that are required for the solution) can only be calculated along the diffusion path and therefore, for n > 2 , a single couple will not be enough to calculate all of them correctly. [ABSTRACT FROM AUTHOR]

A cross-scale analysis method for predicting the compressive mechanical properties of tin-based bearing alloy was proposed based on microstructure finite element simulation and molecular dynamics (MD) simulation. The actual metallographic microstructure of tin-based bearing alloy taken by optical microscopy was utilized to construct the representative volume element (RVE) model for the computational modeling. The compression stress–strain curves of β-Sn and Cu6Sn5 obtained by MD simulation were used as the input material property parameters of each constituent phase in RVE model for the microstructure finite element analysis. The compression simulation was carried out for the tin-based bearing alloy with the microstructure containing Sn matrix and Cu6Sn5 phase. The results show that the simulation analysis method can predict the compression strength and elasticity of the studied tin-based bearing alloy well by comparing the simulated results with the experimentally obtained data. It is hoped that this paper can provide a simulation method for realizing the prediction of the mechanical properties based on microstructure and revealing the microscope mechanism of materials, thus providing theoretical guidance for the micro-design of high-performance tin-based bearing alloy. [ABSTRACT FROM AUTHOR]

Fatigue life of titanium and titanium alloys is frequently reduced if the load holds at the maximum stress are introduced, which is termed dwell debit. Many factors affect dwell fatigue of titanium alloys, like stress state, level and ratio, alloy chemistry, microstructure and microtexture, holding time and temperature. Dwell sensitivity of titanium alloys is usually attributed to the phenomenon of load shedding, which is a time-dependent redistribution of stress from so-called 'weak' to 'strong' grains possessing different crystallographic orientations. Stress concentration leads to crack initiation and formation of quasi-cleavage facets in 'strong' grains. Another factor contributing to dwell sensitivity of titanium alloys is time dependent strain accumulation, which is observed even at room temperature. In the paper, the effect of load holds and volume fraction of primary α phase on the fatigue behavior of Ti-6Al-4V alloy at the temperature of 150°C was investigated. Two variants of bi-modal microstructure of the alloy were obtained by means of the heat treatment. Stress controlled fatigue tests with and without hold time at maximum load and constant load creep test were carried out. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) is one of the most ideal machining methods for difficult-to-cut material of U71Mn alloy. Therefore, it is vital to obtain the electrochemical characteristics of the material. In this paper, these characteristics are measured with an electrochemical station, and a series of experiments are conducted to verify them. The electrolyte solutions of 15 wt.% NaNO3 and 15 wt.% NaCl are selected for the experiments. The polarization experimental results indicate a broader range of passive regions in the NaNO3 electrolyte solution compared with that in the NaCl. This means that a higher voltage is required to break down the passive film in ECM experiments. Meanwhile, the current efficiency of the alloy is measured in 15 wt.% NaNO3 and 15 wt.% NaCl. The results indicate that the current efficiency of U71Mn alloy in NaCl electrolyte solution is higher than that in NaNO3 electrolyte solution. The electrochemical characteristics of U71Mn alloy are verified with a series of single-factor experiments, and reasonable machining parameters are obtained. The suitable range of machining voltage is 10 to 20 V, and the range of inter-electrode gap is 0.1 to 0.2 mm in these two electrolyte solutions. Finally, multi-parameter experiments are carried out in these two electrolyte solutions to obtain machining samples. The experimental results show that 15 wt.% NaNO3 proved to be a better electrolyte solution for U71Mn alloy, the surface roughness (SR) of the workpiece is Sa 0.72 μm, and the material removal rate (MRR) is 0.096 g/min. [ABSTRACT FROM AUTHOR]

In the realm of additive manufacturing, powder bed fusion (PBF) is recognized as an innovative and highly effective technique for manufacturing titanium-based materials. With an understanding of and regulation for the complex microstructural evolution that occurs during the PBF process, several previous studies have been conducted to enhance the reliability, efficiency, and performance of the PBF through investigation and optimization of microstructure evolution in PBF. These studies have examined various aspects, including feedstock materials, process parameters, and post-processing techniques, in order to gain a comprehensive understanding and control over the progression of microstructure in the PBF. Process parameters are widely acknowledged as critical determinants in the PBF process for titanium-based materials, significantly influencing the quality in 3D printed components. Previous studies have provided an in-depth discussion of the effects of process parameters, such as laser power, scanning speed, and hatching space, on the microstructure evolution of Ti-based materials. The primary objective of this review paper is, therefore, to provide a comprehensive and clear explanation of recent efforts, with a particular focus on investigating the complex evolution of microstructures in Ti-based materials during the PBF process. This thorough discussion is devoted to providing a comprehensive understanding of the effects of process parameters on the evolution of microstructures in Ti-based materials. [ABSTRACT FROM AUTHOR]

The prediction of damage for each material during plastic deformation processes is crucial yet challenging due to the significant variability of prediction results according to ductile fracture criteria. This paper presents a solution for determining the critical damage values of AA1050-O aluminum alloy sheets as well as predicting workpiece damage in combined deep drawing processes using a combination of experiments and numerical simulations based on Freudenthal, Cockroft-Latham, and normalized Cockroft-Latham ductile fracture criteria. First, the depth of indent obtained from the Erichsen cupping test was applied to identify the critical values through numerical simulation using the Freudenthal, Cockroft-Latham, and normalized Cockroft-Latham ductile fracture criteria. Then, the critical values were used to predict the fracture for AA1050-O alloy sheets in the combined deep drawing processes. The prediction was validated through the execution of a combined deep drawing process experiment on AA1050-O alloy sheets employing a hydraulic press. The results demonstrated the superiority of the Cockroft-Latham criterion over other criteria in predicting both failure and non-failure occurrences in the combined deep drawing processes of AA1050-O alloy sheets, particularly in forecasting failure initiation, moment, and position. The combination of experiments and numerical simulations exhibited its potential to predict fracture criteria in other forming processes. [ABSTRACT FROM AUTHOR]

The ordered γ′-(Ni, Cu)3Al is a crucial strengthening phase that improves the high-temperature resistance of Cu-based alloys, so it is important to predict the kinetic evolution of the composition and microstructure of the phase for high-temperature applications. Herein, this paper discusses the temporal evolution of the composition and coarsening of the γ′ phase in a model ternary Cu50Ni37.5Al12.5 (at%) alloy during isothermal aging at 600, 700, 800, and 900 °C for 1–36 h. It is found that the γ′ phase composition evolves linearly toward a binary γ′ phase as the aging time increases during the process of aging at 800 and 900 °C, which cannot be predicted by the ternary phase diagrams alone. Meanwhile, through the utilization of the aforementioned linear law, the γ phase composition can be predicted at a given temperature within the alloy by determining the volume fraction of the γ′ phase. Additionally, the activation energy for coarsening decreases, and the coarsening rate of the γ′ phase increases owing to the higher diffusion rate of Cu at high temperatures. The addition of microalloying elements with strong enthalpic interactions is beneficial for reinforcing the structural stability of the γ′ phase. This work provides a simple method for the compositional analysis and performance prediction of Cu–Ni–Al alloys at elevated temperatures and sheds light on the subsequent compositional design and optimization of Cu-based high-temperature alloys. [ABSTRACT FROM AUTHOR]

Titanium alloys have broad application prospects in the field of marine engineering due to their excellent corrosion resistance and comprehensive mechanical properties. Titanium alloys, when connected with other metals, such as copper-nickel alloys, could produce two distinct effects. On the one hand, the passive film gives titanium alloys positive potential, which could accelerate galvanic corrosion of negative-potential metals. On the other hand, the passive film could obstruct current flow and prevent further development of galvanic corrosion. In this paper, Potentiodynamic Polarization, Electrochemical Impedance Spectroscopy, and Electrochemical Noise techniques were utilized to investigate the galvanic corrosion behavior of B10/Ti80 under simulated seawater environment. The corrosion morphology and product composition were studied using Scanning Electron Microscope and X-ray Photoelectron Spectroscopy. The above experimental results showed that Ti80 and B10 served as the anode and cathode respectively in the early stages of corrosion (within 2.5 h of immersion), due to the incomplete formation of the passivation film on Ti80. While in the latter stages of corrosion, due to the positive shift of Ti80's potential by passivation, there was a noticeable accelerated corrosion effect on B10, which was proportional to the area ratio of Ti80/B10 and showed a gradually stable trend after 28 days of immersion in the seawater. [ABSTRACT FROM AUTHOR]

The chemical compositions optimization, microstructure and mechanical properties of high-solid-fraction (40–60%) semi-solid A380 alloy were investigated in this paper. The effects of content of Si and Cu on preparation temperature of the semi-solid slurry were researched by thermodynamic calculation and differential scanning calorimetry. Based on commercial A380 alloy, the compositions (Si and Cu) were optimized for the preparation of high-solid-fraction slurry with swirled enthalpy equilibrium device. The results indicated that as the content of Si and Cu decreased, the temperature range of process window widened, which is beneficial for the slurry preparation and following semi-solid rheo-diecasting process. With the optimized A380 alloy, bracket casting for truck was produced by high-solid-fraction semi-solid diecasting. The microstructure and mechanical properties of tensile samples took from the real castings were quantitatively characterized. The solid fraction of 58% and average grain diameter about 60 μm were achieved with sphere-like primary Al (α-Al) phase in casting parts. After T6 heat treatment, the ultimate tensile strength, yield strength and microhardness of real casting parts were 381.9 MPa, 332.6 MPa and 133.6 HV, which were increased by 61.9%, 181.3% and 69.7% compared with that of as-cast state, respectively. High solid fraction enables the AlSi8Cu3 perform complete T6 heat treatment and low gas porosity, so the optimized A380 alloy exhibits higher strength than that of low-solid-fraction semi-solid rheo-diecasting and the presence of the high-density precipitates (θ′) provided better reinforcement effect. The micro-mechanism of fracture reveals that the as-cast samples were quasi-cleavage, while the T6 heat-treated samples were dimple and quasi-cleavage. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of computational fluid dynamics (CFD) analysis to assess castability, porosity, molten metal fluidity and other technological properties of a new Al–Ce alloy. A thermodynamic analysis of a new Al–Ce alloy is done to obtain the physical properties as a function of temperature across both solid and liquid phases. These properties are then used to build the CFD model of the full casting process from initial pouring through to final solidification of the part, here an example of a heavy duty MOR mount is used. This process shows that CFD can be used to assess the capability of the alloy to properly fill the mold, as well as give predictions where scattered porosity or large-scale defects may occur in the casting. Unlike the commercially available software (e.g., ProCAST, SOLIDCast, MAGMASOFT®) the complex 3D-analysis of the stress/strain fields in cast parts is not performed at this time. The simulation are performed in Star-CCM+ using a volume of fluid analysis. However, the availability of free software for assessing the required thermodynamic/thermo-physical properties of new alloys (OpenCALPHAD) and CFD codes such as OpenFOAM® makes the developed option attractive and economical to adapt in future, especially for the analysis of new Al–Ce alloys, for which the available data does not exist. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the stress relief annealing rate on residual stress was investigated using molecular dynamics simulation, and the difference in mechanical properties of workpieces before and after stress relief annealing was analyzed using nanoindentation simulation. The results show that the Stacking faults and dislocation motions are blocked during the heating stage to shift the stresses, and the residual stresses are released by the dislocation reaction dominated by Shockley dislocations. In the cooling stage, the Stair-rod dislocation reaction forms the Stacking Fault Tetrahedra to release the residual stress. The dislocation density is directly proportional to the residual stress during the stress relief annealing process, and the decrease in dislocation density leads to a decrease in surface hardness. [ABSTRACT FROM AUTHOR]

The application of shape memory alloys is very suitable for developing pipe joints, and Fe-Mn-Si memory alloy pipe joints show great promise. This paper studied the variation rule and microscopic mechanism of the strain recovery rates of Fe-24Mn-6Si-7Cr-3Ni alloy pipe joints made by three different hot working technologies: casting, forging, and rolling. The strain recovery rate of as-cast pipe joints rose monotonously with the increasing thermomechanical training cycle. As-cast pipe joints' superior shape memory effect mainly came from the large grain size of 662.70 μm and the low density of annealing twin boundaries. On the other hand, the shape memory effects of forging and rolling pipe joints were restricted by the high densities of annealing twin boundaries and grain boundaries, respectively. Although the shape memory effects had a lower upper limit, their strain recovery rates climbed quickly. Following the third annealing, the remaining second-phase particles precipitated according to the ε -martensitic distribution orientation, and this contributed to the shape memory effects of as-cast and forging pipe joints. During adjusting the solution treatment parameters for as-cast pipe joints, it was found that as-cast pipe joints without solution treatment exhibited a notable superiority over the solution-treated ones when less thermomechanical training was performed. [ABSTRACT FROM AUTHOR]

Treatment options for osteoarticular diseases include physical ultrasound therapy, assistive de-vices, and biomedical bone alloys. Biomedical alloys are wide used in biomedical applications due to their favorable properties for biocompatibility, mechanical strength, and corrosion resistance. Among titanium-based alloys, those with remarkable mechanical properties are especially popular for medical implant applications. However, the Young's modulus (E) of current titanium-based alloys is much higher than that of human bone, which can cause bone tissue damage. To address this issue, new titanium-based alloys have been designed using the cluster-plus-glue-atom model, which modifies glue atoms. First-principles calculations were used to study the mechanical stability and elastic properties of these new structures. The results show that these new structures have elastic properties within the range of human bone and exhibit excellent ductility. In particular, the lowest E can reach about 7 GPa. These new titanium-based alloy structures are suitable for use as bone implants due to their appropriate elastic properties. This paper provides theoretical guidance for the alloy design of titanium-based alloys for use in biomedical materials. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of defects on tensile failure of additive manufactured AlSi10Mg alloy focusing particularly on the role of large pancake shaped loss of fusion (LOF) defects lying perpendicular to the build direction (BD). Time-lapse in situ synchrotron radiation X-ray micro-computed tomography during straining reveals how, when tested parallel to the BD, the LOF defects extend laterally with straining connecting to other defects and giving rise to low plasticity and an essentially brittle failure mode. When they are aligned edge-on to the straining direction, failure is characterised by a ductile cup-cone failure with significant elongation of the defects axially and extensive necking prior to failure. The soft fish-scale melt pool boundaries were also found to affect the fracture path. These results highlight the anisotropic effect of loss of fusion defects in controlling tensile ductility and the need to minimize their size and aspect ratio. In cases where these cannot be fully eliminated the component should be fabricated such that the BD is not aligned with the dominant in-service loading direction. [ABSTRACT FROM AUTHOR]

TiAl intermediate compound is an important material for high-temperature applications due to its superior creep resistance and oxidation resistance. It is suitable for high-pressure compressors and low-pressure turbine blades of advanced military aircraft engines. TiAl intermediate compound is an excellent substitute for nickel-based superalloys, as it can decrease weight by 40% and greatly enhance aircraft thrust-to-weight ratio. In this paper, the microstructure evolution and the mechanical properties of Ti2AlNb alloy with a 3.0 wt.% W and 0.1 wt.% Y addition obtained by blending elemental ultrafine powders was investigated by XRD, SEM-EDS, and mechanical testing device. The findings show that high relative density of 0.9945, and the excellent mechanical properties of Ti2AlNb–3W–0.1Y alloy can be obtained through isothermal sintering for 3 hour in a furnace with controllable argon atmosphere flow of 200 mL/min at 1,500°C. The alloy's tensile strength, yield strength, and elongation reach 1,030 MPa, 913 MPa, and 15.1% at 700°C, respectively. Meanwhile, the 3 wt.% of element W is added to the alloy to form (TiW)C as the second strengthening phase, which is uniformly distributed in the matrix of Ti2AlNb. The addition of Y element at 0.1 wt.% into the alloy can act as an effective scavenger of oxygen and inhibit the unsatisfactory precipitation of the brittle α2-phase in the Ti2AlNb alloy. Compared to the alloy without additions, the Ti2AlNb alloy with 3 wt.% W and 0.1 wt.% Y demonstrated 13.5% and 19.35% improvements in the fracture resistance at 25°C and 700°C, respectively. The alloy's yield strength was increased as well. The evolution regularity of the main metallography is (Ti2AlNb–TiAl–Ti3Al) → (Ti2AlNb–Ti3Al) → (Ti2AlNb–Ti3Al–(TiW) C) during the isothermal sintering of Ti–22Al–25Nb–3W–0.1Y alloy at 1,500°C. This study provides technical guidance for the preparation of ultrafine TiAl-based alloy powder and high-temperature aerospace applications [ABSTRACT FROM AUTHOR]

The paper considers principles of combining technology for preparing new powder materials from solid alloy waste by electroerosive dispersion of T5K10 alloy waste in a liquid working medium (water) and compaction technology by spark plasma sintering. It is established by experiment that hard alloys made of electroerosion dispersed T5K10 alloy particles prepared by spark plasma sintering under rapid heating conditions and a short working cycle duration have better physical and mechanical properties compared with industrial hard alloys from which the initial powder particles were obtained due to suppression of grain growth and obtaining an equilibrium state within a submicron grain size. [ABSTRACT FROM AUTHOR]

This paper makes an improvement on the determination of the temperature, bowing parameter, and antimony (Sb) composition effects on the fundamental band gap energy of InAs1−xSbx ternary alloys for infrared (IR) photodetection. The present study was carried out in a broader temperature range from cryogenic to room temperature for the entire alloy range, and a reasonable analysis has also been carried out. Meanwhile, a proposed expression for the band gap bowing parameter temperature dependence has been established. The optical cut-off wavelength can be further tuned over a significant range up to 14 μm or more by altering the stoichiometry of InAs1−xSbx alloys. The three Varshni and Bose–Einstein thermodynamic parameters were found to exhibit a parabolic trend with Sb composition. Consequently, the quadratic equations relating these parameters to Sb composition were derived. The relatively weak band gap temperature coefficient reported here is hoped to offer an improvement on infrared photodetector (IR-PD) stability. Also, the average phonon energy and the corresponding electron–phonon coupling interaction strength were investigated versus Sb composition. The available experimental results were used, where possible, to confirm our theoretical estimates, and the agreement is satisfactory. We expect that the present work will be helpful in designing and improving the photodetection properties of IR optoelectronics devices. Additionally, it provides a firm basis for our forthcoming determination of the electronic band structure properties of InAs1−xSbx based superlattices. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the impact of various cutting parameters on the micro-cutting mechanism of high-entropy alloy FeCoCrNiAl0.6. It examines the cutting force, cutting temperature, and residual stress of FeCoCrNiAl0.6 high-entropy alloy micro-cutting using the finite element simulation method. The research findings reveal the following: as the cutting depth increases, the three-dimensional cutting force gradually rises, exhibiting a significant growth trend, and there is a positive correlation between them. Increasing the cutting speed results in small fluctuations in cutting force, which remains relatively stable. Moreover, the cutting force gradually increases with higher feed rates, demonstrating a positive correlation. The maximum temperatures of the tool surface and chip surface increase with higher cutting depth, and they are positively correlated. There is a positive correlation between cutting temperature and cutting speed. With increased cutting speed, the maximum temperature of the cutting surface steadily rises. Simultaneously, during cutting, the chip temperature increases at a faster rate compared to the tool temperature with increasing cutting speed. As the feed rate continuously increases, the maximum temperatures of the chip surface and tool surface show a steady growth trend, and there is a positive correlation between them. During the cutting process, the workpiece surface is predominantly characterized by residual compressive stress. Under different cutting depths, the absolute value of the maximum residual compressive stress on the workpiece surface decreases. Under the influence of cutting speed, when the cutting speed is below 110 mm/s, the residual compressive stress on the workpiece surface demonstrates an increasing trend. For cutting speeds between 110 and 170 mm/s, the workpiece surface initially exhibits a decreasing trend followed by an increasing trend. Increasing the feed rate leads to an increase in the absolute value of the maximum residual compressive stress on the workpiece surface. [ABSTRACT FROM AUTHOR]

In this paper, a state-of-the-art Artificial Intelligence (AI) technique is used for a precipitation hardening of Ni-based alloy to predict more flexible non-isothermal aging (NIA) and to examine the possible routes for the enhancement in strength that may be practically achieved. Additionally, AI is used to integrate with Materials Integration by Network Technology, which is a computational workflow utilized to model the microstructure evolution and evaluate the 0.2% proof stress for isothermal aging and NIA. As a result, it is possible to find enhanced 0.2% proof stress for NIA for a fixed time of 10 min compared to the isothermal aging benchmark. The entire search space for aging scheduling was ~ 3 billion. Out of 1620 NIA schedules, we succeeded in designing the 110 NIA schedules that outperformed the isothermal aging benchmark. Interestingly, it is found that early-stage high-temperature aging for a shorter time increases the γ′ precipitate size up to the critical size and later aging at lower temperature increases the γ′ fraction with no anomalous change in γ′ size. Therefore, employing this essence from AI, we designed an optimum aging route in which we attained an outperformed 0.2% proof stress to AI-designed NIA routes. [ABSTRACT FROM AUTHOR]

In this paper, a Cu-3.20Ni-0.61Co-0.75Si-0.19Cr-0.15 Mg (wt.%) alloy was subjected to hot compression at temperatures of 700–950°C and strain rates of 0.001–10 s−1. The constitutive equations were established using a strain-related Arrhenius model and a feed-forward artificial neural network (ANN) model. Evaluation showed that the ANN-type constitutive equation had a high Pearson correlation coefficient of 0.9997 and a low mean squared error of 2.55 MPa2; thus, it was more accurate to describe the flow behavior of the Cu-Ni-Co-Si-Cr-Mg alloy than the strain-related Arrhenius-type constitutive equation. The hot processing maps in the conditions of non-linear dissipation governed by the two constitutive equations were also established. Evaluation showed that the ANN-type hot processing maps successfully predicted unstable deformation and dynamically-recrystallized microstructure and thus had better performance than the Arrhenius-type hot processing maps. The microstructure of the Cu-Ni-Co-Si-Cr-Mg alloy after hot compression was also characterized in detail. The microstructural features were unstable deformation for the compression at 700°C and 0.001 s−1, uneven deformation for the compression at 700°C and 1 s−1, equiaxed subgrains for the compression at 950°C and 0.001 s−1 and equiaxed grains and annealing twins for the compression 950°C and 1 s−1. [ABSTRACT FROM AUTHOR]

In the present paper, the study of amorphous-crystalline transformation in (Se80Te20)94−x Ge6Bix (x = 0, 1, 2, 4, 6, 8, 10 and 12 at.%) chalcogenide alloys has been done using non-isothermal differential scanning calorimetry (DSC). Characteristic temperatures indicate that the samples with x = 1 at.% and x = 6 at.% can be considered as a critical configurations at which the system becomes a chemically ordered alloy. Kissinger and Moynihan approaches which utilized dependence of glass transition temperature (Tg) on heating rate (α) are used to deduce activation energy of glass transition (Eg). Crystallization process is characterized by various kinetic parameters such as activation energy and frequency factor deduced using different methods. Dietzel, Hruby, Saad and Poulin criteria are employed to assess glass forming ability and thermal stability of investigated alloys. The alloy with x = 12 at.% of Bi content has highest ∆T confirms maximum thermal stability, further validated from the values of Hruby parameter (Kgl) and thermal stability parameter (S). The fragility index infers that the composition studied in the present study is made from strong glass forming liquids. [ABSTRACT FROM AUTHOR]

In the context of product innovation, there is an emerging trend to use Machine Learning (ML) models with the support of Design Of Experiments (DOE). The paper aims firstly to review the most suitable designs and ML models to use jointly in an Active Learning (AL) approach; it then reviews ALPERC, a novel AL approach, and proves the validity of this method through a case study on amorphous metallic alloys, where this algorithm is used in combination with a Random Forest model. [ABSTRACT FROM AUTHOR]

The possibility of producing complex metallic parts in various industries can be attributed to the selective laser melting (SLM) additive manufacturing method. As a powder bed fusion technique, SLM fabricates the product layer by layer. The state-of-the-art research on SLM, the metallic alloys utilized in the process, and the surface morphology of fabricated parts are discussed in this paper. The present report contributes to the literature by providing a comprehensive overview of the surface morphology of metallic alloys fabricated using the SLM additive manufacturing method. The article covers recent research on SLM, metallic alloys used in the process, and the surface morphology of fabricated parts. Insights into the challenges and opportunities of SLM for the fabrication of metallic parts with desired surface properties are provided. In the first part, parameters representing surface morphology are introduced and types of surface defects are viewed. Subsequently, influence of process variables during the production phase is discussed in-depth, overviewing several parameters such as laser, scanning, and geometric parameters. Surface morphology enhancement, namely in situ treatment, post-processing, and finishing-machining techniques, is viewed separately by classifying them into subtopics, in respect of their improvement effectiveness. Mechanical aspects of the microstructure and surface are evaluated in correlation with the surface morphology. The discussion of the findings considering the advantages and disadvantages of this technology is summarized finally. It is concluded that laser parameter effect's significance depends on the work alloy. In the literature, process parameters are systematically studied, and better surface quality and favourable surface morphology of as build surfaces are possible. Moreover, it has been concluded that the surface morphology and quality of SLMed products can be improved with in situ techniques and post-treatments. Relieving residual stresses and decreasing porosity on the surface (various types of holes, pinholes, vacancies, etc.) during SLM operation are possible by base plate heating, powder preheating, and re-scanning. It is also noticed that the machinability studies of SLMed parts mainly focus on mechanical machining such as grinding and milling. Studies on the correlation between surface morphology of SLMed parts and mechanical properties are relatively scarce comparing to works on SLM production parameters. Finally, as an emerging technology for vast production of industrial items, it is concluded that surface morphology of SLMed products needs systematic correlation studies between process parameters and surface results. [ABSTRACT FROM AUTHOR]

The paper studies theoretically of the dependence of the structural and vibrational properties of the Li–Cu surface alloy and Li adlayer with the 1.2 ML Li–(2 × 2)–Cu(111) structure on the adsorption sites. The equilibrium atomic configuration, frequency, and polarization of the vibrational modes as well as the local density of phonon states have been calculated. All calculations were performed using the interatomic potentials obtained by the embedded atom method. The data obtained on the structural parameters are in agreement with the available experimental data. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of milling time on the microstructural changes, density, and mechanical properties of Al-5 wt.% Al12Mg17 nanocomposite. In this study, aluminum matrix nanocomposites, reinforced by the nanoparticles of a novel Al12Mg17 complex metallic alloy, were synthesized via high-energy planetary ball milling and hot-pressing processes. Powder characterization showed the morphology and size change of nanocomposite mixture to form large flakes during the first 20 h of milling time, and then the particle size reduced. Investigation of hot-pressed samples with different milling times revealed that increasing the milling time reduced the interparticle spacing, and, consequently, a uniform dispersion of Al12Mg17 nanoparticles in the Al matrix was achieved after 30 h of ball milling. Well-distributed nanoparticles led to more effective crystalline growth during the hot pressing. With increasing the milling time up to 30 h, the hardness and compressive strength of the nanocomposites continuously increased, because of smaller crystalline sizes and also well-distributed nanoparticles, and then declined due to the deteriorating effect of porosities. Based on microstructural factors, density, and mechanical properties, the optimum milling time of 30 h was determined for nanocomposite fabrication. [ABSTRACT FROM AUTHOR]

The anisotropy, inhomogeneity, high brittleness, and hardness of Al-50wt% Si alloy challenge its machinability in conventional processing. To solve the problem of serious machined surface defects on the groove bottom, the longitudinal ultrasonic vibration–assisted milling (LUVAM) technique was developed for Al-50wt% Si alloy groove machining. Based on the characteristics of tool-workpiece separation and frictional reversal, the variation of cutting force and cutting temperature with amplitude was studied. The influence of amplitude on the material removal mechanism and surface formation characteristics of Al-50wt% Si alloy groove bottom under different material removal rates (precision and non-precision milling (PM and NPM)) were the focus of this paper. The results show that the probability of Si particle breakage and spalling in PM decreases with the increase of amplitude, and the particles are sheared instead. The ultrasonic dressing effect reduces the anisotropy of Al-50wt% Si alloy. However, in NPM, the ultrasonic dressing effect weakens and the dynamic impact effect increases when the amplitude exceeds the critical value 2.5 μm. Additionally, the groove bottom surface features are related to the down milling (DM) and up milling (UM) methods. UM is the better method for PM of Al-50wt% Si alloy, and DM is the better method for NPM of Al-50wt% Si alloy. This work suggests that under different material removal rates, the machined groove quality of Al-50wt% Si alloy can be improved by selection of optimized amplitude in LUVAM. [ABSTRACT FROM AUTHOR]