Cast Aluminum Alloy Research Articles

Rapid investment casting of nanotechnology-enhanced aluminum alloy 6061

Rapid investment casting of nanotechnology-enhanced aluminum alloy 6061

Effect of over-ageing on the tensile and torsional fatigue properties of the AlSi7Cu0.5 Mg0.3 precipitation-hardened cast aluminium alloy

The objective of this work is to evaluate the influence of over-ageing on the high cycle fatigue behaviour of the AlSi7Cu0.5Mg0.3 cast aluminium alloy. It is generally accepted that over-ageing has a large influence on the behaviour of these materials, however its effect on the fatigue strength is less understood. This work provides an experimental investigation of the effect of over-ageing on high cycle fatigue strength in both tensile and torsional loading conditions. It is shown that the torsional fatigue strength is more sensitive to over-ageing when compared to the tensile fatigue strength and that the fatigue defect sensitivity is negligible for torsional loads, in contrast to tensile loading conditions. The experimental results indicate that this is due to a change in the crack initiation mechanism, going from initiation in the matrix for torsion loads to initiation from casting defects for tensile loads. An original two-steps approach is proposed to rationalise the effect of over-ageing on the fatigue strength, with particular emphasis on decoupling the respective contributions from defects and the mechanical properties. This approach is used to build normalised Kitagawa-Takahashi diagrams that highlights the reduced defect sensitivity under tensile loads for the most severe over-ageing condition.

Secondary phase increases the elastic modulus of a cast aluminum-cerium alloy

Alloying in metal castings is one of the principal methods of strengthening an alloy for various structural and functional applications, but very rarely does it modify an alloy’s elastic modulus. We report a methodology of combining isostructural Laves phases to form a multi-component, high symmetry, isotropic phase that was discovered to enhance the elastic modulus of a cast aluminum alloy to 91.5 ± 7.4 GPa. Flux grown single crystals of the rhombicuboctahedron phase (RCO), so named for the observed morphology, were used to enhance understanding of the structure and mechanical properties of the phase. The pure RCO phase’s structure and site occupancies were co-refined using x-ray and neutron diffraction. Dynamic nanomechanical testing of the cast alloy shows the primary RCO phase has a high, relatively isotropic, elastic modulus. This RCO containing aluminum alloy is found to have a specific modulus that exceeds that of the leading Al, Mg, Steel, and Ti alloys.

Microstructure evolution of a novel low-silicon cast aluminum alloy modified with Mn and Cr during solution treatment

The evolution of eutectic Si, the precipitation behavior of dispersoids and microhardness change of the α-Al matrix in a Mn + Cr modified Al-Si-Mg-Cu alloy during solution treatment were investigated. The results revealed that the evolution of eutectic Si was divided into four paths during solution treatment: Dissolution, splitting, spheroidization and coarsening. Meanwhile, numerous α-Al(FeMnCr)Si dispersoids were precipitated in the eutectic region and the α-Al dendrite arms after solution treatment for 30 min. Due to differences in precipitation behavior, three different dispersoid precipitation zones were formed in the dendrite arms, including the dispersoid-free zone (DFZ) near the grain boundaries, coarse dispersoid zones (CDZ) located in the dendrite cores, and the remaining fine dispersoid zones (FDZ). The bimodal size distribution of the dispersoids within intradendritic regions were closely related to the micro-segregation of Mn and Cr. The precipitation of coarse grain boundary phases exhausted the Fe solute near the grain boundary, which was mainly responsible for the formation of the DFZ. Moreover, there was a partial coherent interface between the dispersoids and the α-Al matrix. The evolution mechanism of matrix microhardness can be well explained by dispersion strengthening effect

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.

Preparation of high-strength and low-shrinkage composite salt cores by binder jetting and vacuum impregnation

ABSTRACT Binder jetting (BJ) technology was employed combined with vacuum impregnation to fabricate alumina-reinforced Na2SO4-NaCl water soluble composite salt cores (WSCSC), intended for manufacturing aluminum alloy castings featuring intricate cavity structures. The bending strength and sintering shrinkage rate of WSCSC were investigated to discern the influences of alumina content, vacuum impregnation pressure and time, accompanied by a detailed analysis of the microstructure and reinforcement mechanism. The findings reveal that WSCSC containing 40 wt.% alumina exhibits exceptional mechanical properties, demonstrating a bending strength of 29.13 MPa, which is 197% higher than that of WSCSC without alumina. Furthermore, when the vacuum impregnation of saturated brine is conducted at a pressure of 30 KPa for 90 s, the resulting WSCSC possesses a sintering shrinkage rate of 4.94%, reflecting a significant reduction of 73.5% compared to that of WSCSC without vacuum impregnation treatment. Microstructural analyses show that alumina, as a stable secondary phase, can refine the NaCl grains within WSCSC, deflecting cracks and elongating their propagation paths, thereby remarkably enhancing the bending strength. Moreover, the fine inorganic salt particles crystallized and precipitated from saturated brine during the drying process are filled in the internal pores of WSCSC through vacuum impregnation, dramatically reducing the sintering shrinkage rate. Ultimately, the high-strength and low-shrinkage WSCSC parts were successfully manufactured.

The Effect of Solute Suppressed Nucleation Effect and Latent Heat on the Grain Refinement of Cast Aluminum Alloy

The Effect of Solute Suppressed Nucleation Effect and Latent Heat on the Grain Refinement of Cast Aluminum Alloy

The impact of small Zr addition to Al–Ni cast alloy for elevated temperature applications

Most aluminium casting alloys are based on the eutectic system Al–Si, which has weak thermal properties. Alloys from the eutectic Al–Ni system on the other hand have higher thermal stability and good casting properties and are therefore promising for casting applications. Using casting simulations, a copper mold was designed to achieve cooling rates above 100 K/s with the aim of producing a Zr-rich supersaturated solid solution. Microstructural analysis revealed that the addition of Zr leads to notable changes in the microstructure characterised by the formation of primary Al3Zr and αAl dendrites. Subsequent heat treatment revealed that Zr-enriched alloys undergo significant age hardening, which showed an improvement in microhardness due to effective Al3Zr precipitation.

Thermally Sprayed Coatings for the Protection of Industrial Fan Blades.

This paper presents a study on thermally sprayed coatings. Coatings produced by high-velocity oxygen-fuel spraying HVOF and plasma spraying deposited on the A03590 aluminum casting alloy are tested. The subject of this research concerns coatings based on tungsten carbide WC, chromium carbide Cr3C2, composite coatings NiCrSiB + 2.5%Fe + 2.5%Cr, mixtures of tungsten and chromium powders WC-CrC-Ni, mixtures of carbide powders with the Cr3C2-NiCr + the composite 5% NiCrBSi and WC-Co + 5% NiCrBSi. The aim of this research is to find a coating most resistant to the erosive impact of particles contained in the medium centrifuged by industrial rotors. The suitability of the coating is determined by its high level of microhardness. The hardest coatings are selected from the coatings tested and subjected to abrasion tests against a sand particle impact jet and the centrifugation of a medium with corundum particles. It is found that the most favorable anti-erosion properties are demonstrated by a coating composed of a mixture of tungsten carbide and chromium carbide WC-CrC-Ni powders. It is concluded that the greatest resistance of this coating to the erosive impact of the particle jet results from the synergistic enhancement of the most favorable features of both cermets.

Solid-state friction rolling repair technology for various forms of defects through multi-layer multi-pass deposition

The current Friction Stir Welding (FSW) based solid-state defect repairing method is an ideal repair technology for high-strength aluminum alloy. However, due to the limitation of pin length and the existence of shoulder, the stirring pin cannot penetrate deep into the root of defects and is difficult to extend in the width direction, which poses great challenges for components with large defects, such as one-dimensional, two-dimensional and volume defects. To overcome these limitations, this study successfully achieved effective repair of various forms of defects using the solid-state Friction Rolling Repair (FRR) technology through multi-layer multi-bead deposition. The microstructure and mechanical properties of the repaired ZL114A cast aluminum alloy joints were investigated. The results demonstrate well-bonded repaired boundaries, significant grain refinement at the junction between the repaired area and boundary, and ultimate tensile strength exceeding 80 % of base material strength. The average grain size of the repaired area can reach a minimum of 2.82 μm. The grain refinement degree of the side joint of the surface defect repair sample is higher than that of the bottom joint, and the corner joint of the bottom surface shows the highest proportion of recrystallized grains. Fracture locations were consistently within the interior of the repair zone in tensile specimens, indicating superior properties at side joints compared to those within the interior. The research proves that FRR has the ability to repair a variety of typical defects, including one-dimensional, two-dimensional and volume defects, in the process of processing and service, which lays a foundation for the industrial application of FRR.

Co-, Ni- and Fe-rich grain-boundary phases enhance creep resistance in θ′-strengthened Al-Cu alloys

Microstructural evolution and creep response were investigated in the cast Al-5.0Cu-0.3Mn-0.2Zr (wt.%) alloy with and without addition of slow-diffusing, intermetallic-forming elements Fe, Ni, or Co. Baseline Al-5.0Cu-0.3Mn-0.2Zr alloy exhibits high creep resistance at 300 °C, up to ∼75 MPa, which is attributed to high-aspect-ratio, intragranular θ′-Al2Cu precipitates that effectively suppress dislocation climb. However, θ′-Al2Cu precipitate-free zones form along grain boundaries upon heat treatment, whose extent is amplified during subsequent creep. Such weak regions experience dislocation creep, leading to strain localization and acceleration of grain-boundary sliding. Adding Ni and Co, individually or in combination, leads to the formation of grain-boundary precipitates (Al9Co2, Al3Ni2) which are resistant to coarsening, thus suppressing the formation of θ′-Al2Cu precipitate-free zones. This microstructure provides high creep resistance at stresses up to 75–80 MPa, with strain rates much lower than in unmodified Al-5.0Cu-0.3Mn-0.2Zr. Adding Fe, which results in extensive decoration of grain boundaries with coarsening-resistant Al7Cu2Fe, and then increasing the Cu content to compensate for the Cu loss to this new phase, leads to a new Al-7.4Cu-1.6Fe-0.3Mn-0.2Zr alloy with creep resistance at 300 °C that surpasses known cast aluminum alloys. Adding Fe to improve the creep resistance of Al-Cu alloys is both cost-effective and sustainable. Our findings offer guidelines applicable to various alloy systems on controlling the evolution of precipitate-free zones and its ensuing effects on creep deformation.

Effect of rare earth Ce and Y on microstructure and viscosity of ZL114A alloy

To investigate the impact of rare earth on the fluidity of casting aluminum alloy during the filling process, the study measured the effects of rare earth (Ce, Y) content and the mischmetal (Ce / Y) on the viscosity of ZL114A alloy melt using a viscosimeter. The results show that for a single rare earth element, when the addition amount of Ce and Y is 0.4 wt%, the grain size and viscosity reach a minimum, with average grain sizes of 45.42μm and 43.54μm respectively, and the solidification range decreases by 4.23°C and 4.61°C respectively, with Y having a better effect than Ce; compared with the alloy without rare earth elements, the grain growth mode changes from independent nucleation to outward extension form. For mixed rare earth elements, the refinement effect is better than that of a single rare earth element, but the viscosity is higher. When the Ce/Y mass ratio is 1/3, the grain size and viscosity reach a minimum, with an average grain size of 40.75μm and a solidification range shortened by 8.92°C; when the proportion of Y is higher, the alloy shows better refinement of the microstructure and viscosity improvement. Rare earth elements have the potential to enhance the fluidity and solidification structure of ZL114A alloy. This study offers valuable technical insights for optimizing the casting process and mold design.

Sub-rapid solidification microstructure characteristics and control mechanisms of twin-roll cast aluminum alloys: A review

Rapid growth in industrial sectors such as automotive and shipbuilding has highlighted the significance of strip casting technology to produce lightweight alloys, particularly aluminum alloys widely used in both industrial production and daily life. Twin-roll casting (TRC), as an economically and environmentally friendly method for slab/strip production and processing, has attracted significant interest from researchers. However, the development of TRC aluminum alloys faces many challenges due to limited understanding of microstructural characteristics and control mechanisms. To further enhance comprehension of TRC aluminum alloys, this article reviews the influencing parameters, control methods, and existing issues related to TRC sub-rapid solidification (SRS) microstructure. It firstly summarizes TRC equipment types and their solidification characteristics, followed by a detailed analysis on key parameters affecting the evolution of TRC microstructure including rolling speed, roll separation force (RSF), and heat transfer coefficient (HTC). Finally, solutions to TRC defects are summarized and evaluated alongside their underlying mechanisms. This article provides a comprehensive review of the characteristics and control mechanisms of TRC microstructure while offering valuable insights for the future production of high-quality TRC aluminum strips.

Casting Production in Poland Versus European Trends in 21st Century

This article presents changes of the total casting production volumes and of the production of castings made from basic casting alloys in Poland, in Europe and worldwide in years 2001–2021. Analogous casting production parameters were compared for Poland, Europe and countries being the leading European and global manufacturers in years 2001, 2011 and 2021. The leading casting manufacturers in Europe (with the manufacturing volume exceeding 1 million tons in the mentioned years) include Germany, Italy, the Ukraine, France and Spain. For years, the largest casting manufacturer worldwide has been China. In 2001–2021, global casting production increased from ca. 68 million tons to ca. 97 million tons (i.e. by ca. 42%), whereas the European one decreased from ca. 17 million tons to ca. 12 million tons (i.e. by close to 30%). In the analyzed period, the Polish production volume grew from ca. 0.75 million tons to ca. 0.88 million tons (i.e. by ca. 17%). The presented data reveal the decreasing importance of gray cast iron and cast steel and the increasing one of ductile cast iron and aluminum alloys. However, the Polish average annual growth rate for aluminum alloy casting production was 10.3%, whereas the global one was 3% and the European one 0.7%.

Microstructural and mechanical properties of Al-Al2O3 micro and nanocomposite fabricated by stir casting

ABSTRACT The current study examines the relationship between the microstructure and tribological characteristics of Al-Si alloy composites reinforced by secondary phase nano SiC particulates synthesis via the stir casting process. The results of wear testing of stir-cast SiC metal matrix composites including up to 12 weight percent fine (75–100 µm) and coarse (125–150 µm) size particles were obtained from cast aluminium alloy. It was discovered via microstructural investigation that the aluminium alloy and SiC particles have good interface bonding. However, at greater amounts (12 wt.%) of fine size reinforcement, clustering of reinforced particles is observed. In addition, results state that finer size particles agglomerate more in the matrix than coarser size particles at greater reinforcement levels. In addition, increasing the amount of SiC particles in the matrix enhanced the hardness of the base alloy. However, when the size of the SiC particles was reduced, the hardness of the composite increased dramatically. Better wear resistance was observed for higher SiC reinforcement levels, while higher forces were also associated with a corresponding increase in wear rate. A combined mode of adhesive and abrasive wear mechanisms is responsible for composite wear, according to a scanning electron microscopy (SEM) investigation of worn surfaces.

Nanotechnology-Enabled Rapid Investment Casting of Aluminum Alloy 7075

Abstract Rapid investment casting with additively produced molds can offer excellent surface finishes, tight dimensional tolerances, and complex geometries for high-performance metal parts in a rapid fashion. However, there is a long-standing challenge in the investment casting of high-strength aluminum alloy (AA) 7075 due to its hot cracking susceptibility and severe solidification shrinkage. Here, we show the unprecedented rapid investment casting of AA7075 by applying nano-treating technology, whereby a low-volume fraction of nanoparticles is dispersed into metal to modify its solidification behavior and microstructure. TiC nanoparticles were able to effectively modify both primary and secondary phases while suppressing the hot cracking susceptibility of AA7075 during solidification. Despite the low cooling rate, nano-treated AA7075 exhibits fine equiaxed grains with an average size of 47.1 μm, in contrast to the large dendritic grains measuring 714.8 μm in pure AA7075. Nano-treated AA7075 parts produced by rapid investment casting exhibited exceptional tensile strength and ductility in both as-cast and heat-treated conditions. This study highlights the potential of investment casting high-performance alloys which were traditionally considered impossible to fabricate by this method.

Critical Challenges in the Anodizing Process of Aluminium–Silicon Cast Alloys—A Review

The microstructure of the substrate plays a crucial role in the anodizing process. Anodizing cast aluminum alloys is quite challenging due to the higher levels of alloying elements present compared to pure aluminum. Elements such as silicon, iron, and copper significantly impact the growth and quality of the anodic layer. Additionally, anodizing parameters such as electrolyte composition, current density, and temperature are critical in determining the morphology and thickness of the anodic film. The casting process, surface condition, and post-treatment also affect the properties of the anodic layer. Optimizing these parameters is essential to achieve a durable and high-quality anodic layer. This work aims to provide a comprehensive understanding of the various factors affecting the anodizing of cast aluminum alloys and the properties of the anodic layer, including its thickness, corrosion resistance, and wear resistance.

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

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

An inverse estimation of frozen sand mold-melt heat transfer coefficient in the solidification of A356 alloy

Casting aluminum alloys is widely used in aerospace, rail transportation, automotive, ships, and other fields. The frozen sand mold casting (FSMC) technology provides a greener and low-cost solution for the sand mold casting industry, which has a better operating environment than the resin sand mold casting and a higher degree of subcooling for solidification process. The interfacial heat transfer coefficient (IHTC) is a significant parameter that affects the structure and properties of the frozen casting. It is also an important boundary condition in numerical simulation. In this paper, a frozen sand mold casting (FSMC) process thermal conductivity problem (IHCP) inversion model is proposed based on the 1-D heat transfer assumption using a combination of finite difference method (FDM) and conjugate gradient method (CGM). The inversion model is validated for its rationality and accuracy in terms of experiments and numerical calculations, respectively. The IHTC is determined under various frozen sand mold casting conditions, including different initial frozen temperatures, water contents, and molding sand. The accuracy of results is verified by comparing the experimental and numerical data. A new method is provided for determining IHTC in frozen casting.

Challenges by latent heat calculation – Competition among analytical and computational methods

Determining the latent heat of multi-component cast aluminum alloys is complex. These alloys solidify within the mushy zone, with their latent heat release influenced by factors like composition, cooling rate, and microstructure. Techniques such as DSC and DTA, along with software tools like JMatPro, FactSage, and ThermoCalc, can determine this value, understand solidification parameters, and calculate latent heat. This paper introduces a novel approach using Newtonian, Fourier, and Energy Balance methods simultaneously, for the first time, to calculate the latent heat of pure aluminum and its AlSi7Cu1 alloy. These methods offer advantages in foundry conditions and require no specialized operator for data interpretation. Commercial software typically provides parameters for standard alloys only, necessitating alternative sources for accurate data. Thermal analysis techniques offer a reliable method to acquire missing parameters and calculate latent heat with high precision. Comparing the accuracy of these methods for pure aluminum and its AlSi7Cu1 alloy, using DSC measurement data and commercial software values, indicates successful application on the foundry floor to determine thermophysical properties accurately.