Alloy Research Articles

The aging-hardening behavior of short-time in high pressure die casting AlSi9MgMnZn alloy

Short-time aging is an effective industrial technique for enhancing the mechanical properties of high pressure die cast (HPDC) aluminum alloy components. However, the evolution of precipitation behavior during short-time aging of HPDC alloys remains unclear. In this study, the short-time aging behavior of HPDC AlSi9MgMnZn alloy was investigated. The results show that the AlSi9MgMnZn alloy exhibits effective aging-hardening, with an increment in hardness of approximately 30 HV through the optimal short-time aging treatment (aged at 180 °C for 120 minutes). Higher aging temperatures led to reduced peak hardness and rapid over-aging above 220 °C. The microstructure observation indicates that the peak short-time aging promotes the simultaneous precipitation of β″ precipitates, GP zones and nano Si phases. The contribution of different strengthening mechanisms to hardness was estimated, implying that the coexistence of β″ precipitates and GP zones can provide a positive contribution to aging-hardening during short-time aging. Moreover, as the aging temperature increases, the appearance of β′ precipitates reduces the strengthening effect, leading to a decrease in hardness.

High-Performance Ultraviolet to Near-Infrared Antiambipolar Photodetectors Based on 1D CdSxSe1-x/2D Te Heterojunction.

Antiambipolar heterojunctions are regarded as a revolutionary technology in the fields of electronics and optoelectronics, enabling the switch between positive and negative transconductance within a single device, which is crucial for diverse logic circuit applications. This study pioneers a mixed-dimensional photodetector featuring antiambipolar properties, facilitated by the van der Waals integration of one-dimensional CdSxSe1-x nanowires and two-dimensional Te nanosheets. This antiambipolar device enables flexible control over carrier transport via gate voltage, thus paving new paths for future optoelectronic devices. Furthermore, by precisely managing the stoichiometry of the ternary alloy CdSxSe1-x nanowires, fine-tuning of the nanowire band structure is achieved. This allows for customizable heterojunction band alignment (Type I and Type II), enabling adjustable band alignment. Through sophisticated band engineering, optimal Type II band alignment is achieved at the CdSxSe1-x/Te interface, significantly enhancing the device's photoelectric conversion efficiency through the synergistic effect of different dimensional materials. Exhibiting outstanding photoresponse across a broad spectral range from ultraviolet to near-infrared, especially under 450 nm illumination, the CdSxSe1-x/Te heterojunction photodetector demonstrates superior performance, including an impressive responsivity of 284 A W-1, a high detectivity of 1.07 × 1017 Jones, an elevated external quantum efficiency of 7.83 × 104 %, and a swift response time of 11 μs. Ultimately, this customizable antiambipolar photodetector lays a solid foundation for the advancement of next-generation optoelectronic technologies.

Determination of equivalent crack length for voids in metallic alloys based on continuum damage mechanics modeling

Metals contain different kinds of spatial defects significantly reducing the fatigue performance. Accurate defect-based life prediction methods are required to improve structural integrity analysis and life design reliability. The present work developed a method to determine the equivalent crack length for defects based on continuum damage mechanics. The spatial effects of defects in the calculation of the equivalent crack were quantified and verified by fatigue tests. It is confirmed that the equivalent crack length of both slit and elliptic defects is affected not only by the defect geometry but also by the applied load. Based on the equivalent crack and combined with Paris’ law, the predicted fatigue lives of various slit holes under different loading orientations are within the double scatter band and are much more accurate than the conventional projection method.

Prediction of Sm- (Co, Cu, Fe, Zr) binary alloys’ thermodynamic parameters by improved miedema model

Abstract At present, the calculation results of the original Miedema mixing enthalpy model are still somewhat different from the experimental results. Therefore, it is necessary to improve the calculation accuracy of the Miedema model to promote the development of the Miedema model and its application in the design of samarium-cobalt permanent magnet alloys. To solve this problem, the enthalpies of mixing of Sm- (Co, Cu, Fe, Zr) binary alloys were calculated in this paper by using the modified model. The mixing enthalpy (DH), excess entropy (SE), excess Gibbs free energy (GE), component activity (α) and binary Gibbs free energy of Sm-Co, Sm-Fe were calculated. The results show that the improved Miedema model can better match the experimental values. Sm- (Co, Fe, Cu) binary alloys are easy to generate intermetallic compounds. And Sm-Zr is difficult to form intermetallic compounds. The DH, SE and GE of Sm- (Co, Fe) are negative, and there is a large negative deviation from Raoult's law for the activity of each component compared to the ideal solution. The Gibbs free energies for both SmCo5 and Sm2Co17 precipitation reactions are less than zero in the temperature range between 1550 and 1620 K. The Sm2Co17 phase is thermodynamically more stable than the SmCo5 phase.

Preparation of electroless deposition of NiTiZr(P) quaternary alloy and their properties

The exceptional super elasticity and corrosion-resistance of Ni-Ti alloys have attracted a lot of attention and interest lately for a wide range of applications, and complex alloy components could be prepared effectively by different preparation techniques. Ni(P), Ni-Ti(P), Ni-Zr(P), and Ni-Ti -Zr(P) binary, ternary, and quaternary alloys were coated on mild steel by electroless deposition which is a method of plating metallic films on a substrate by the reduction of metallic complex ions in solution with the aid of reducing agent from an alkaline bath. The ternary Ni-Ti-Zr(P) alloy is considered to be one of the most promising high-temperature SMAs. SEM, XRD and EDS were used to examine the morphology, phase composition and elemental composition which demonstrate the microstructure of the deposits. The mechanical characteristics of the samples were examined through scratch test and micro hardness analysis and the value increased from 261 HV200 to 405 HV200 and that the coefficient of friction raised significantly from 0.23 to 3.5 owing to the presences of added elements in Ni(P) matrix. Polarization analysis and EIS were tested to evaluate the corrosion properties of coated samples in a non-deaerated 3.5 %wt. (NaCl) solution. The outcomes indicate that as the amount of Ti-Zr elements in the bath raised, the corrosion potential became more positive and the corrosion current density decreased to 14.903 μA/cm2. Furthermore, Ni-Ti-Zr(P) alloy coating strengthens corrosion resistance in comparison to Ni(P).

The effect of cobalt alloying on the phase transformation kinetics of Ni-Ti alloys

This study investigates the influence of cobalt (Co) alloying addition and heat treatment temperature on the phase transformation behaviour controlling the superelasticity and shape memory effect (SME) of Nickel-Titanium (Ni-Ti) alloys, commonly known as nitinol. The microstructural evolution upon heat treatment conducted at a temperature ranging from 440 to 560 °C was thoroughly analyzed via Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), and Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS). Increase in heat treatment temperatures from 470 °C up to 530 °C led to the dissolution of particles present in as-received (cold-worked) condition. It was determined that Co addition into the Ni-Ti alloy system resulted in a change in the nucleation and growth kinetics of Ti-rich precipitates, leading to the formation of larger and fewer particles during processing. Both binary and ternary alloys showed a decrease in austenite finish temperature (Af) with increasing heat treatment temperatures, however, the rate of decrease was found to be higher for Co containing ternary alloys. This is linked with faster structural relaxation when Co is present and evidenced by lattice size variation during heat treatment. It is highlighted that heat treatment methodology needs to be tailored to the specific alloy composition for controlling superelasticity and SME via alloy design.

Basics of the reaction kinetics on metallic alloys.

Kinetics of heterogeneous catalytic reactions are often complicated by various factors, and from the perspective of statistical physics the development of the corresponding models is frequently challenging especially in the case of practically important alloy catalysts. To extend the basics in this area, I use a generic kinetic model of N_{2} formation inthe NO reaction with such species as CO or H_{2}. The focus is onthe reaction on the surface of a bimetallic alloy with low integral fraction of one of the metals so that the alloy is formed only at the surface. The main goal is to illustrate the specifics of the reaction kinetics and to clarify the accuracy of various approximations which are often inevitable for the analysis of such systems. The key results are as follows. (i) In the baseline one-metal case with the Langmuir-type equations, the model predicts the existence of the optimal adsorbate binding energy corresponding to the maximal reaction rate. (ii) With suitable substitution of the symbols, the equations employed for a uniform surface [item (i)] can be used for the mean-field description of reaction on the surface of a random alloy. In particular, the maximum in the dependence of the reaction rate on the binding energy is converted to the maximum with respect to the alloy composition. (iii) The reaction kinetics on the random-alloy surface have been described exactly. The corresponding maximum in the reaction rate is lower and somewhat smeared compared to that predicted in the mean-field approximation for an alloy or for the optimal monometallic catalyst. (iv) The reaction kinetics have been scrutinized also in the case of two-dimensional (2D) segregation of metal atoms at the surface in the limits of slow and rapid adsorbate diffusion between the spots. The kinetics are shown to be qualitatively different in these limits and also compared to the random-alloy case. (v) The thermodynamic criteria for 2D segregation of metal atoms at the surface have been derived as well.

Magnetic casein/CaCO3/Fe3O4 microspheres stimulate osteogenic differentiation

The quality of life is significantly impacted by bone defects, which calls for the creation of optimum restorative materials with particular qualities. Current repair materials, such as metal alloys, polymer scaffolds, and bone cement, have a number of drawbacks, such as poor fracture toughness, non-degradability, and insufficient osteogenic ability. To address these challenges, we designed a novel magnetic casein/CaCO3/Fe3O4 microspheres (CCFM), combining biodegradability, osteoinductivity, osteoconductivity, and osteogenesis properties together. In vitro studies confirmed the outstanding biocompatibility and osteogenic differentiation effects on MC3T3-E1 cells of CCFM, highlighting their potential as a promising bone regeneration platform for clinical applications. As a novel bone repair material with superparamagnetic properties, CCFM not only possess good osteoinductivity, osteoconductivity, and osteogenesis properties but also can remain in the lesion location for a long time under an external magnetic field, representing a significant advancement in the field of bone tissue engineering and offering new possibilities for effective bone defect remediation and patient care.

An experimental study on material removal rate and surface roughness of Cu-Al-Mn ternary shape memory alloys using CNC end milling

Abstract This study investigates the impact of Computer Numerical Control (CNC) milling parameters on Cu-Al-Mn SMAs (Shape memory alloys) to evaluate the effects on Surface Roughness (SR) and Material Removal Rate (MRR). The primary variables examined comprise of cutting speed, feed rate, and depth of cut. Results indicate that the Shape Memory Effect (SME) is higher in Copper Aluminium Manganese (CAM 3) compared to CAM 1 and CAM 2, with SME improving from 3.5% to 5.5% as Manganese (Mn) content increases, reflecting an increase in dislocations within the metal's crystal structure. Surface roughness increases with higher feed rates and depths of cut but decreases with increased cutting speed. MRR shows a positive correlation with feed rate, depth of cut, and cutting speed, though it decreases with higher Mn content. Notably, CAM 3 exhibits lower MRR compared to CAM 1 and CAM 2. Scanning Electron Microscopy (SEM) reveals that at lower feed rates (0.10 mm/rev), the surface is smooth and free of ridges or feed marks, while at higher feed rates (0.18 mm/rev), noticeable surface imperfections and plastic deformation occur. The addition of Mn improves surface smoothness and machinability, it also affects MRR. Further suggesting that Mn content and milling parameters significantly influence both the mechanical properties and machinability of Cu-Al-Mn SMAs respectively.

Uniformly dispersed zinc-tin alloy as high-performance anode for aqueous zinc ion batteries

Uncontrolled dendrite and side reactions of aqueous zinc ion batteries (AZIBs) hinder their commercial application. To overcome these obstacles, a novel zinc alloy anode for multifunctional AZIBs was designed by incorporating metal elements into the zinc anode. The metal elements are intended to improve the overall electrochemical performance of the battery by solving the zinc anode problem in an “incorporation” manner. In this study, the effect of Sn-induced surface structure reconstruction on the diffusion and deposition behavior of Zn2+ was investigated using binary zinc alloy (Zn@Sn) as a zinc anode. The zinc anode with Zn (002) crystal plane as the preferred crystal plane was able to inhibit the disordered growth of zinc dendrites, and the introduction of Sn elements enhanced the anti-hydrogen evolution reaction ability of the zinc anode. At a current density of 1.2 mA cm–2, the Zn@Sn symmetric cell was able to maintain stable operation for 1000 h, demonstrating a more prominent deposition/stripping stability. This work provides a promising strategy and new insights into the design of electrolyte-anode interfacial protection.

Features of Solid-Solution Hardening and Temperature Dependence of the Critical Shear Stress in Binary and Multicomponent Alloys

The paper analyses the hardening of binary and multicomponent solid solutions (including high-entropy alloys (HEAs)); addresses the notion of a compositional–cluster structure of binary solid solutions with unlimited solubility to propose an equation describing the concentration dependence of the critical shear stress; presents findings from a comparative analysis of the temperature dependences for critical shear stress (yield stress) for a series of binary and multicomponent solid solutions and pure metals with b.c.c. and f.c.c. lattices; considers potential mechanisms, which lead to a ‘plateau’ on the temperature dependence of critical shear stress for binary and multicomponent solid solutions and for pure metals; discusses the specifics of athermal hardening of HEAs and proposes a relatively simple equation for assessing their athermal hardening; and addresses the capabilities of using the x-ray diffraction to determine the root-mean-square displacements of atoms from ideal positions at crystal-lattice sites and crystal-lattice microdistortions in multicomponent solid solutions.

Effective Atomic Radii of Constituent Elements and Their Temperature Dependence in Quaternary and Ternary Subset Alloys Derived from CrMnFeCoNi High-Entropy Alloy

Effective Atomic Radii of Constituent Elements and Their Temperature Dependence in Quaternary and Ternary Subset Alloys Derived from CrMnFeCoNi High-Entropy Alloy

Research progress on the preparation of irradiation-resistant coating based on PVD technology

Nuclear energy is essential for the future development of countries. However, both structural and functional components of nuclear power equipment are facing severe challenges of nuclear irradiation damage after experiencing irradiation growth and irradiation creep. How to avoid irradiation damage to nuclear power equipment has become a hotspot in international research and development of surface protection technology. Deposition of protective coatings on the underlying object surface or in bulk materials has been considered as a near-term solution to enhanc functional components. Different substrate materials are selected according to other service conditions within the reactor. Suitable material selection combined with relevant optimization can significantly increase the service life of materials. This review summarizes recent research on several categories of anti-irradiation coatings prepared by physical vapor deposition technology for current industrial applications. These includes metallic, ceramic, composite and high entropy alloy coatings. The review endeavors to impart a thorough understanding of the properties of these selected anti-irradiation coatings, from the fundamental aspects of their substrate materials to their practical applications across diverse settings. It explores not only the current research progress but also the potential avenues for future advancements. Additionally, the intricate relationships between coating formulations, their resistance to irradiation, and their ultimate performance in various environments are illuminated in this paper.

Corrosion behavior of 2A97 Al−Cu−Li alloys in different thermomechanical conditions by quasi-in-situ analysis

As a promising material in the aircraft industry, 2A97 Al−Cu−Li alloy exhibits high corrosion susceptibility that may limit its application. In the present work, to illustrate the influences of precipitate and grain-stored energy on localized corrosion evolution in 2A97 Al−Cu−Li alloy, cold working and artificial aging were carried out to produce 2A97 Al−Cu−Li alloys under different thermomechanical conditions. Quasi-in-situ analysis, traditional immersion test and electrochemical measurement were then conducted to examine the corrosion behavior of 2A97 alloys. It is revealed that precipitate significantly affects Cu enrichment at corrosion fronts, which determines corrosion susceptibility of alloys, whereas grain-stored energy distribution is closely associated with localized corrosion propagation. It is also indicated that quasi-in-situ analysis exhibits a consistent corrosion evolution with traditional immersion tests, which is regarded as a proper method to explore localized corrosion mechanisms by providing local microstructural information with enhanced time and spatial resolutions.

Twin experiments and detailed investigation of data assimilation system for columnar dendrite growth in thin film

Accurately predicting dendrite growth during alloy solidification is crucial for enhancing the quality of metallic products. Recently, data assimilation has emerged as a promising tool for integrating two cutting-edge methods for studying dendritic growth, viz. in situ X-ray observation experiments and phase-field (PF) simulations, to elucidate important parameter(s) of the simulation and produce a “digital twin” of a growing dendrite. This study was conducted to evaluate the performance of a data assimilation system, employing an ensemble Kalman filter, through systematic twin experiments focused on columnar dendrite growth in a thin film of a binary alloy. The results show that the data assimilation system effectively estimates multiple parameters and dendrite morphology simultaneously. Furthermore, two approaches—domain decomposition method and parameter estimation method from a part of the domain—to reduce computational costs are investigated. Both methods can effectively reduce the computational cost of data assimilation. Additionally, data assimilation using voxel observation data of varying resolutions, mimicking actual X-ray images, is performed. The study findings discourage the direct use of voxel data owing to incompatible PF simulations. PF relaxation computation is explored as a solution for generating observation data with smooth PF profiles. The results show that while relaxation computation enhances the estimation accuracy for high-resolution voxel data, its efficacy diminishes for low-resolution data. These detailed investigations of data assimilation provide valuable insights for utilizing actual in situ X-ray observation data in dendrite growth studies.

Microenvironment engineering of non-noble metal alloy for selective propane dehydrogenation

Microenvironment engineering of non-noble metal alloy for selective propane dehydrogenation

Oxidation kinetics of Ti6Al4V alloy deposited by wire arc additive manufacturing using argon gas as processing atmosphere

Ti6Al4V alloy is currently the most common metal alloy of the α+β phase type, its application is increasing as it has excellent properties at elevated temperatures. The main users of Ti6Al4V alloy are industries like of aerospace, naval, and biomedical; therefore, Ti6Al4V alloys one of the most studied material worldwide. One of the great advantages that Ti6Al4V alloy offers is the possibility of manufacturing components in situ by means of additive technologies.. Similar studies, in additive manufacturing, have reported the formation of titanium oxide on the surface of the material, followed by an oxygen-enriched region called "α-case". By means of thermogravimetric analysis, the oxidation effect on the surface of Ti6Al4V samples, obtained by wire arc additive manufacturing as well as samples from conventional manufacture, were studied. Argon gas, with an oxygen partial pressure of 1x10-5 atm, was used as the oxidation atmosphere within a range of 550°C to 950°C and oxidatión times of 60 min and 180 min. For the oxidation reaction, the kinetic analyses led to calculate the activation energy as 250 kJ/mol and 166 kJ/mol for the Ti6Al4V alloy processed by conventinal and additive manufacturing, respectively. The results of the of thermogravimetric analysis were fitted to a parabolic-type kinetic model. Furthemore, a mathematical model was proposed to predict the oxidation kinetics. The experimental data were fitted to the mathematical model in the range of 750 - 950°C for Ti6Al4V alloy by wire arc additive manufacturing. The oxidized microstructures were analized by optical and electronic microscopy finding α-case on the surface of the samples.

Survey of Microstructures and Dimensional Accuracy of Various Microlattice Designs Using Additively Manufactured 718 Superalloy.

Microlattices hold significant potential for developing lightweight structures for the aeronautics and astronautics industries. Laser Powder Bed Fusion (LPBF) is an attractive method for producing these structures due to its capacity for achieving high-resolution, intricately designed architectures. However, defects, such as cracks, in the as-printed alloys degrade mechanical properties, particularly tensile strength, and thereby limit their applications. This study examines the effects of microlattice architecture and relative density on crack formation in the as-printed 718 superalloy. Complex microlattice design and higher relative density are more prone to large-scale crack formation. The mechanisms behind these phenomena are discussed. This study reveals that microlattice type and relative density are crucial factors in defect formation in LPBF metallic alloys. The transmission electron microscopy observations show roughly round γ″ precipitates with an average size of 10 nm in the as-printed 718 without heat treatment. This work demonstrates the feasibility of the additive manufacturing of complex microlattices using 718 superalloys towards architectured lightweight structures.

Evaluating the Impact of Oxidation Heat Treatment and Dual Opaquing Techniques on Enhancing Metal-Ceramic Bond Strength.

This research aims to assess the impact of oxidation heat treatment (OHT) and dual opaquing techniques on enhancing the bond strength between metal and ceramic. Eighty rectangular patterns with dimensions of 0.5x3x25 mm (according to ISO 9693-2012) were fabricated in a custom-made silicon mold by using auto-polymerized pattern resin material. These rectangular patterns were cast using base metal alloys. The samples were split into two primary groups: group A, subjected to OHT, and group B, without oxidation treatment. Each primary group was then split up into subgroups according to the application of single layers (group A1, B1)or double layers (group A2, B2) of opaque porcelain.After pre-surface treatment and Ceramco 3 paste opaque application, dentin porcelain (Ceramco 3) wasapplied to the mid-region of the samples, followed by firing to achieve a standardized thickness. Flexural strength determination was conducted via a three-point bend test performed on the universal testing machine (UTM) (Instron Corp., Model 2519-107, USA), adhering to ISO standard 9693. Post-testing failure types were analyzed by morphological assessment of debonding surfaces via a scanning electron microscope (SEM). The statistical analysis was performed with SPSS version 16, incorporating ANOVA for intergroup analysis and independent t-tests for intragroup comparisons. Group A2 exhibited the highest mean flexural bond strength (P<0.05) at 41.85 MPawhen compared to group A1 at 37.60 MPa, group B2 at 35.47 MPa, and group B1 with the least mean flexural bond strength at 30.41 MPa. SEMobservations revealed cohesive bond failure for groups A1, A2, and B2and adhesive bond failure for groupsB1. It is evident that OHT and opaquing technique are important factors in determining the bond strength of ceramo-metal restorations. When combined, these techniques greatly increase the overall success and durability of metal-ceramic restorations, underscoring their significance in contemporary dental prostheses.

Evaluating a Fe-Based Metallic Glass Powder as a Novel Negative Electrode Material for Applications in Ni-MH Batteries

Metallic glasses (MGs) are a type of multicomponent non-crystalline metallic alloys obtained by rapid cooling, which possess several physical, mechanical, and chemical advantages against their crystalline counterparts. In this work, an Fe-based MG is explored as a hydrogen storage material, especially, due to the evidence in previous studies about the capability of some amorphous metals to store hydrogen. The evaluation of an Fe-based MG as a novel negative electrode material for nickel/metal hydride (Ni-MH) batteries was carried out through cyclic voltammetry and galvanostatic charge–discharge tests. A conventional LaNi5 electrode was also evaluated for comparative purposes. The electrochemical results obtained by cyclic voltammetry showed the formation of three peaks, which are associated with the formation of Fe oxides/oxyhydroxides and hydroxides. Cycling charge/discharge tests revealed activation of the MG electrode. The highest discharge capacity value was 173.88 mAh/g, but a decay in its capacity was observed after 25 cycles, contrary to the LaNi5, which presents an increment of the discharge capacity for all the current density values evaluated, reached its value maximum at 183 mAh/g. Characterization analyses performed by X-ray diffraction, Scanning Electron Microscopy and Raman Spectroscopy revealed the presence of corrosion products and porosity on the surface of the Fe-based MG electrodes. Overall, the Fe-based MG composition is potentially able to work as a negative electrode material, but degradation and little information about storage mechanisms means that it requires further investigation.