Lightweight Metal Alloys Research Articles

Enhancing corrosion resistance of lightweight metal alloys through laser shock peening

In this study, we investigated the effects of laser shock peening (LSP) on the corrosion resistance of lightweight metal alloys, specifically AA6061 and AZ31. LSP was performed underwater, using a nanosecond pulse laser and without using a protective coating or layer on the workpiece. The corrosion behaviors of these alloys were analyzed through electrochemical tests, including open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements. The results demonstrated that LSP significantly improved the polarization resistance, and higher laser power intensities led to increased corrosion resistance and reduced corrosion rates. This enhancement in anti-corrosion performance is attributed to the formation of a protective oxide layer on the surface, acting as a barrier against corrosion. The findings underscore the potential of laser surface treatment as a viable technique for enhancing the corrosion resistance of lightweight metal alloys.

Napredak i budući trendovi aditivne proizvodnje žicom i električnim lukom (WAAM)

Over the past three decades, extensive research has been conducted on WAAM (Wire and Arc Additive Manufacturing), a production technology that traces its origins back almost a century with its initial patent. This technology has garnered increasing attention due to its capability to fabricate large near-net-shape metal products. The utilization of existing welding equipment for the heat source and material feedstock in WAAM offers the advantage of lower initial investment costs. Originally gaining prominence in the aerospace industry, it primarily focused on the utilization of lightweight metal alloys. However, recent advancements have broadened the scope of WAAM to encompass numerous products, including functionally graded materials (FGMs) and the combination of diverse alloys. This study seeks to unveil the latest breakthroughs and potential avenues in WAAM technology, offering valuable insights and recommendations for future research endeavors.

Characterization of friction stir-based linear continuous joining of aluminium alloy to structural polymer

Dissimilar continuous joining of lightweight metal alloys to structural polymer is a major manufacturing challenge, demanding feasible and reliable solutions. Through-slot extrusion joining (TSEJ) is a friction stir-based processing technique investigated in the manufacturing of continuous linear joints between aluminium alloy AA5754 overlapping structural polymer polyether ether ketone (PEEK). An intermediate rigid and thin titanium extrusion die protects the polymer locally from thermal degradation and promotes the formation of a continuous double hook-like feature of extruded aluminium into the polymer component along the joint path. The structure of the joint provides macro-mechanical interlocking between the joined components. A set of four tools, and other key process parameters, were investigated for process stability, tensile-shear strength, and microstructure. The best TSEJ condition is chosen for microstructural analysis via optical microscopy and scanning electron microscopy. Three distinct failure modes were identified. The best condition provided an average tensile-shear load of 110 kN/m. The tool position with bias toward the flow side of the extrusion slot shows to improve the strength of joints. The microstructural analysis along the interface of AA5754 to PEEK exhibits micro-mechanical interlocking, intercalated layers of these materials and adhesion as joining mechanisms.

Lamellar-structured Al-based alloys with high strength and plasticity

We present a novel approach to fabricating lamellar-structured metal alloys with enhanced mechanical properties by hot extrusion of metallic glass ribbon precursors. Using Al-based alloys as an example, we found that hot extrusion of metallic glasses causes significant crystallization, associated with thermal and stress gradients that facilitate the formation of a lamellar structure comprised of ultra-fine-grained (UFG) regions and fine-grained (FG) regions. This heterogeneous lamellar structure allows cooperative yielding and plastic deformation that results in high yield strength (over 750 MPa) in combination with high plasticity (over 40%) under compression. The evasion of conventional strength-plasticity trade-off suggests that hot extrusion of metallic glasses offers a new toolbox to create lightweight and high-performance structural metal alloys.

Microstructure and mechanical properties of aluminium alloy coatings on alumina applied by friction surfacing

By combining lightweight metal alloys with ceramics, it is possible to adapt material properties on stressed parts and thus increase stiffness and/or change the thermal resistance: yet joining such materials is problematic due to the poor wettability of ceramics by molten metals. In this work, the technique of friction surfacing is used to connect alumina (Al2O3) with an aluminium alloy (EN-AW 5083). Despite the fact that Al2O3 has a relatively high coefficient of thermal expansion and a low thermal shock resistance, specimens have been produced showing encouraging results. In order to compensate for these material properties the substrate was preheated to a minimum of 150°C. In tests bonding strengths reached 47.8 MPa and coating thicknesses of 213 μm were achieved; results which are comparable with conventional thermally sprayed coatings. Bonding strengths were determined by using a pull-off adhesion tester and the coating thickness was measured with a laser scanning microscope. Analysis of the joint zone shows no clear evidence of chemical reactions (intermetallic compounds) or diffusion. Mechanical interlocking can only be shown to be accountable for 16% of the bonding strength with investigations turning towards van der Waals forces and their contribution to adhesion.

A novel decision-making approach for light weight environment friendly material selection

Abstract Since the last few decades, the use of light weight automotive is increasing day by day to reduce fuel consumption and vehicle emissions. Now days, the automotive industries are emphasizing more on the use of light weight environment friendly materials (LWEFMs) including aluminium, polymers, magnesium, steel blends and composites due to their several inherent advantages, environmental concerns, government regulations and consumer demand. Light weight metal alloys are much preferable for their low density and high specific strength, as well as other attractive characteristics like high corrosion resistance, dimensional stability, energy saving ability and sustainability. However, deciding on the most competent LWEFM for a distinct application considering multi-perspective criteria is not an easy task to perform and restrain a great challenge for the design engineers. On the other hand, improper material selection often leads to premature product failure with reduced efficiency and poor product performance, thereby negatively affecting the productivity, profitability and status of the organization. In this paper, a humble endeavour is taken to propose a novel and contemporary decision-making approach for LWEFM selection in which criteria weights are computed using the Entropy technique and ranking of the alternatives is determined by an almost unexplored multi-attributive ideal real comparative analysis (MAIRCA) method. Seventeen candidate materials are considered as alternatives for the evaluation with respect to thirteen criteria for an automotive application. It has been observed that Ultra High Strength Steel emerges out as the best material for the considered case study. Comparison with other existing well established methods has also been performed to prove the feasibility and validity of the proposed approach

Design and optimization of high-strain, cylindrical composite skins for morphing fuselages

In contrast to morphing wings, which have been intensively studied and demonstrated, relatively little research has focused on morphing fuselages, which are capable of improving agility and range by using the articulating section as an aerodynamic control surface. Herein, we investigate several spring-reinforced cylindrical geometries representational of an articulating fuselage that operate in large-scale bending without buckling. Finite element models analyze design performance under loading and in bending and are compared to experimental prototypes. Axial compression tests are conducted to compute bending work as a function of articulation angle. Strong agreement between model predictions and experimental measurements is observed. Using mechanics-based graphical materials selection, carbon fiber-reinforced polymer composites or lightweight metal alloys are determined to be the most promising materials for successful designs. For the spring-reinforced design space, machined spring-reinforced designs are superior at lower values of articulation work (<25 N⋅m) while wave spring-reinforced designs dominate at high values (>25 N⋅m) for 25° of articulation.

Enhancing the Structural Performance of Lightweight Metals by Shot Peening

Lightweight metals and metal alloys provide the opportunity to fulfill the exigent weight‐saving requirements for structural components. Mechanical surface treatments, in particular, shot peening and other varieties of impact‐based surface treatments are found to be able to significantly promote the structural application of lightweight metals through enhancing their mechanical performance. Moreover, these treatments have substantiated a notable prospect to modulate the surface–environment interaction of the treated material, bringing in original functionalities in multiple fields of application. Herein, the current state‐of‐the‐art in the implementation of shot peening‐based surface treatments is reviewed regarding lightweight metallic materials. The recent advancements are described focusing on the foremost characteristics of the major lightweight metals commonly used in aerospace, automotive, and biomedical sectors. Emergent applications and the existing challenges are highlighted. Lastly, future perspectives on tailoring the effects of shot peening‐based mechanical surface treatments to boost the appeal of lightweight metals as structural components are provided.

Atomistic simulation of diffusion bonding of dissimilar materials undergoing ultrasonic welding

Ultrasonic welding (UW) process offers the ability to create highly efficient solid-state joints for lightweight metal alloys with low power consumption. During the process, a distinct diffusion layer is observed at the joint interface that undergoes severe plastic deformation at elevated temperature. A hierarchical multiscale method is proposed in this study to predict the diffusion behavior of the UW process of dissimilar materials. The method combines molecular dynamics and classical diffusion theory to calculate the thickness of the diffusion layer at the welded interface. A molecular dynamics model is developed for the first time that considers the effect of transverse ultrasonic vibration to simulate the evolution of the diffusion layer. The effect of ultrasonic vibration at the atomic level is assumed to provide thermal energy at the joint interface and the mechanical movement of atoms. The influence of sinusoidal velocity change during ultrasonic vibration is incorporated by numerically time integrating the diffusivity at different ultrasonic velocity. The simulation result shows that the solid-state diffusivity depends on temperature, pressure, and transverse ultrasonic velocity. Higher temperature, pressure, and ultrasonic velocity result in higher diffusivity leading to larger diffusion layer thickness. This article provides a comprehensive review of the diffusion bonding behavior and its dependence on process variables. It also presents a numerical approach combining molecular dynamics and hierarchical multiscale calculation to predict the diffusion layer thickness for the UW process of dissimilar materials.

Nanoparticle Enhanced Eutectic Reaction during Diffusion Brazing of Aluminium to Magnesium.

Diffusion brazing has gained much popularity as a technique capable of joining dissimilar lightweight metal alloys and has the potential for a wide range of applications in aerospace and transportation industries, where microstructural changes that will determine the mechanical and chemical properties of the final joint must be controlled. This study explores the effect of Al2O3 nanoparticles on the mechanical and microstructural properties of diffusion brazed magnesium (AZ31) and aluminium (Al-1100) joints. The results showed that the addition of Al2O3 nanoparticle to the electrodeposited Cu coating increased the volume of eutectic liquid formed at the interface which caused a change to the bonding mechanism and accelerated the bonding process. When the Cu/Al2O3 nanocomposite coatings were used as the interlayer, a maximum bond strength of 46 MPa was achieved after 2 min bonding time while samples bonded using pure-Cu interlayers achieved maximum strength after 10 min bonding time. Chemical analysis of the bond region confirmed that when short bonding times are used, the intermetallic compounds formed at the interface are limited to the compounds consumed in the eutectic reaction.

Study on thrust force and torque sensor signals in drilling of Al/CFRP stacks for aeronautical applications

Multi-material stack products made of carbon fibre reinforce polymers (CFRP) and light-weight metal alloys, such as aluminium alloys, are becoming increasingly employed for aerospace applications. When composite laminates are stacked with metal alloy sheets, the drilling process becomes more complex due to the diverse properties of the stacked materials which involve different wear mechanisms and different drilling parameters. In this framework, the aim of this paper is to investigate the drilling process of Al/CFRP stacks for aeronautical applications through an experimental testing campaign under different drilling conditions. In order to study the thrust force and torque generated during the drilling process, a multiple sensor system is employed for data acquisition, and an advanced methodology for sensor signal processing in the time and frequency domain is developed.

Cellular Automaton Simulation of Microstructure Evolution for Friction Stir Blind Riveting

Friction stir blind riveting (FSBR) process offers the ability to create highly efficient joints for lightweight metal alloys. During the process, a distinctive gradient microstructure can be generated for the work material near the rivet hole surface due to high-gradient plastic deformation and friction. In this work, discontinuous dynamic recrystallization (dDRX) is found to be the major recrystallization mechanism of aluminum alloy 6111 undergoing FSBR. A cellular automaton (CA) model is developed for the first time to simulate the evolution of microstructure of workpiece material during the dynamic FSBR process by incorporating main microstructure evolution mechanisms, including dislocation dynamics during severe plastic deformation, dynamic recovery, dDRX, and subsequent grain growth. Complex thermomechanical loading conditions during FSBR are obtained using a mesh-free Lagrangian particle-based smooth particle hydrodynamics (SPH) method, and are applied in the CA model to predict the microstructure evolution near the rivet hole. The simulation results in grain structure agree well with the experiments, which indicates that the important characteristics of microstructure evolution during the FSBR process are well captured by the CA model. This study presents a novel numerical approach to model and simulate microstructure evolution undergoing severe plastic deformation processes.

Friction spot joining (FSpJ) of aluminum-CFRP hybrid structures

The employment of various materials (such as lightweight metal alloys and composites) with distinct physicochemical properties in the automotive and aerospace industries has opened a new field of research into the joining of dissimilar materials. Several alternative methods have recently been developed for joining metal-composite multi-material structures. Friction spot joining (FSpJ) is an innovative technique within welding-based joining technologies suitable for metal-composite structures. This work aims to address and overview different aspects of FSpJ. Case-study overlap joints using aluminum alloy AA2024-T3 and carbon-fiber-re-inforced poly(phenylene sulfide) (CF-PPS) were produced. Peak temperatures of up to 474 °C were recorded during the process. Such temperatures are well below thermal decomposition of PPS, and extensive thermal degradation of PPS was not detected by thermal analysis in this work. Microstructure analysis was performed showing usual metallurgical phenomena (recovery and dynamic re-crystallization) taking place with friction-based aluminum joining. Microstructural changes caused an alteration to the local mechanical properties as confirmed by microhardness and nanohardness measurements. Moreover, microstructural analysis of the composite part revealed the formation of a small number of volumetric defects such as pores and fiber-matrix debonding. Bonding mechanisms at the interface were studied into details by microscopy analysis and X-ray photoelectron spectroscopy. The influence of various aluminum surface pre-treatments on the bonding mechanisms and mechanical performance of single-lap shear joints was studied. In addition, fatigue life of the joints was investigated using an exponential model to obtain S-N curves. Finally, the quasi-static strength of the friction spot joints was compared with the state-of-the-art adhesive bonding. Friction spot joints showed 50 % stronger joints than adhesively bonded joints, indicating the potential of the technique to be used for joining lightweight metals to composite materials.

Effect of Surface Texture on the Adhesion Performance of Laser Treated Ti6Al4V Alloy

The growing demand in lighter and safer structures generates the requirement of lighter joining strategies, particularly for lightweight metal alloys, composites, and also joining dissimilar materials together. Titanium alloys stand out as the conventional choice for materials for light weight structures. Adhesive bonding of titanium is an appealing route for joint design, also for the possibility of joining it with dissimilar materials. The realization of a strong joint depends not only on the joint design and type of adhesive, but also on the preparation of the adhering surface. Laser texturing presents advantages compared to common surface preparation processes in terms of eco-compatibility, energetic efficiency, ease of manufacturing, and repeatability. This work presents a preliminary investigation on laser texturing of Ti6Al4 V alloy with a pulsed fiber laser source with the aim to increase surface adhesion for bonding. Particularly, different surface textures are proposed, and laser machining strategies are developed. The results showed that laser texturing provided up to eightfold and 30% higher shear strength compared to plain and sand blasted surfaces, respectively. Failure analysis showed that a margin of improvement is still possible by adapting the surface texture for better cavity filling and reducing surface damage caused by the laser treatment.

Finite element simulation of high speed pulse welding of high specific strength metal alloys

High specific strength metal alloys as aluminium, nickel and titanium alloys are suitable to reduce weight in components for transportation industry. Beside component performances, manufacturability and production efficiency must be considered when substituting classical steels with high specific strength metal alloys. In a way similar to resistance welding a sound autogenously joint can be achieved by discharging a very high current pulse over a very short time that is called high pulsed welding or capacitative discharge welding. In this paper a numerical model was built with the aim to support the evaluation, via a computer aided approach, of the effects of this technique on the high pulsed weldability of some lightweight metal alloys. The model aimed to reproduce the electrical, thermal and mechanical aspects of the high pulse welding process and to evaluate the temperature profile, the piece displacement, the effects of different welding parameters on the weld seam.

Laser Beam Build-Up Welding: Precision in Repair, Surface Cladding, and Direct 3D Metal Deposition

Surface coating, repair, and rapid design changes of high-value components and tools are demanding challenges of modern manufacturing technology. In this field, advanced laser-based techniques are of outstanding importance for the related applications in mould and tool, aircraft and aerospace, as well as automotive industry. Many laser cladding solutions have been transferred into industrial series production within the last years. The motivations for the raising interest are given by the typical features of the technology: on the base of closed CAD/CAM chains, a quick and comprehensive treatment even of complex shaped and highly stressed components is possible. The heat input into the workpiece is less compared to TIG or PTA welding, although a metallurgical bonding to the substrate is guaranteed. Furthermore, the precise material deposition even at small partial areas is an advantageous characteristic. The coating materials include metal alloys (Co, Ni, Cu basis, Titanium, and steel), hard metals (e.g., WC/Co, TiC, and VC with metallic binders), and oxide ceramics (Al2O3/TiO2). Typical base materials are steel, cast iron, and lightweight metal alloys based on Aluminum, Titanium, and Magnesium. The accuracy of the produced 3D structures in the range of 0.1 mm is the highest possible in the group of welding techniques. On the other hand, the available system technology (lasers, powder feeders and nozzles, CAD/CAM systems) permits a very easy and successful integration of the laser technology into manufacturing systems. Examples of application are the surface protection of lightweight automotive motor components, repair and quick modifications of metal forming tools as well as the complete restoration of damaged blades and disks of aero engines and gas turbines.

Rapid solidification of lightweight metal alloys

Abstract Rapid solidification (RS) of the light metals aluminium, magnesium, and titanium can lead to enhanced mechanical properties which can be rationalized in terms of the alloying behavior of these systems. The status of RS alloy exploration for the three lightweight metals is reviewed and suggestions made on possible future directions for alloy development.