Si Phase Research Articles

Influence of heat treatment on microstructure and thermo-physical properties of Al-50wt%Si alloy fabricated by selective laser melting

Herein, we investigate the influence of heat treatment on microstructure and thermo-physical properties of Al-50wt%Si alloy fabricated by selective laser melting (SLM). Microstructure characterizations reveal that SLM and heat-treated Al-50wt%Si alloys are all characterized by the primary Si and eutectic structure consisting of dominant Al matrix and tiny eutectic Si. However, the size of primary Si monotonously increases with increasing the heat treatment holding time at 550 °C. In addition, the SLM Al-50wt%Si alloy displays a highest coefficient of thermal expansion (CTE) among all examined alloys. As the heat treatment holding time increases, the Si precipitates from the Al(Si)-supersaturated solid solution, leading to the formation of a skeleton-like Si phase, which effectively alleviates the thermal expansion. Furthermore, the SLM Al-50wt%Si alloy exhibits a lowest coefficient of thermal conductivity (CTC), since the significantly increased size of primary Si with increasing the heat treatment holding time leads to a substantial reduction in the number of grain boundaries, which severely restricts the scattering of heat transfer phonons. Moreover, theoretical models are employed to calculate the CTE and CTC. Results indicate that the Schapery lower model provides a better prediction of CTE, and the actual CTC values of Al-50wt%Si alloys after heat treatment are closer to theoretical values. These findings can provide new insights into designing Al matrix composites with low CTE and high CTC through microstructural optimization.

The microstructure and electrochemical performance of the Al-10Si-3.5Fe-xZn-yGa alloys for hot-dip galvanizing in low-chloride environments

The microstructure and electrochemical performance of Al-10Si-3.5Fe-xZn-yGa alloys in low-chlorine environments were studied by SEM observation and electrochemical analysis. The microstructure of Al-10Si-3.5Fe-xZn-yGa alloys consisted of Si phase, τ6, and α-Al matrix. The addition of Zn or Ga did not affect the morphology and phase of the microstructure. Pitting corrosion, galvanic corrosion of α-Al matrix with Si phase and τ6, and anisotropic corrosion of τ6 occur in the low-chloride environments for the alloys. The addition of Zn not only promoted the development of pitting pits on the α-Al matrix but also reduced the electrode potential of the α-Al matrix, increased the galvanic corrosion potential difference, and accelerated the corrosion rate of the α-Al matrix. The addition of Ga could induce pitting corrosion on the surface of intact τ6 and α-Al matrix synchronously, reducing both electrode potential and accelerating the alloy's corrosion rate. The synergistic action of Zn and Ga could promote the alloy's sustained activation. Corroded τ6 developed cracks and fragmentation, with the resulting cracks serving as pathways for the ingress and egress of Cl− and other particles, leading to internal corrosion of the alloy. The stress generated during the fragmentation process of τ6 promoted extensive delamination of the alloy surface, preventing corrosion products from covering the alloy's surface.

Microstructural features and mechanical properties of spray -formed hypereutectic Al-Si-Ti alloy

ABSTRACT In the present study, the effect of the addition of Ti on the microstructural and mechanical properties of hypereutectic (Al/15 wt. %Si) spray-formed (SF) alloys has been investigated and compared with as-cast (AC) alloys. Al/15Si and Al/15Si/2Ti alloys were synthesised by spray forming method. The microstructural features of the alloys were explored under an optical microscope, and a scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis were carried out for phase identification. The phase analysis confirmed the presence of α-Al and Si phases in all the alloys, with additional peaks attributed to Al3Ti and AlSi2Ti present in the Al/15Si/2Ti alloys. The microstructure of the SF1 alloy (Al/15Si) consisted of globular, fine Si phases (primary and eutectic) distributed homogeneously in the equiaxed Al matrix. The addition of Ti to the binary SF1 alloy led to the formation of an SF2 alloy (Al/15Si/2Ti) with a fine intermetallic phase of Al3Ti and further spheroidisation of Si particles. The SF1 and SF2 alloys exhibited 30% and 40% greater microhardness, respectively, than did their corresponding AC alloys. With the addition of Ti, the ultimate tensile strength of the SF2 alloy increased by 19% compared to that of the SF1 alloy. Furthermore, a significant increase in yield strength and ductility was observed in the SF alloys compared to the AC alloys. Adding Ti to hypereutectic Al/15Si alloy via the spray-forming method provides a better alternative material for aerospace and automotive applications.

The effect of B and Sb on the corrosion behavior of T6-treated Al–Si–Mg alloys

The influence of B and Sb on the microstructure and corrosion behavior of T6-treated Al–Si–Mg alloys has been specifically studied. It is found that the addition of 0.03 wt% B to Al–Si–Mg alloys results in the lowest corrosion rate (0.02451 mm/y) when immersed in 3.5 wt% NaCl solution for 3 days. This improvement can be attributed to the transformation of coarse dendritic α-Al grains into refined equiaxed grains, which is beneficial for the formation of uniform and compact passive film. In contrast, the Al–Si–Mg alloy with addition of 0.2 wt% Sb shows the highest corrosion rate (0.05795 mm/y), which can be attributed to two reasons. First, the addition of Sb contributes to the transformation of rod-like eutectic Si particles into a spherical morphology, increasing the number of micro-galvanic corrosion sites and thus accelerating the corrosion process. Second, the generated Mg3Sb2 phase, being more noble than the eutectic Si phase, strengthens the micro-galvanic corrosion.

The Influence of Mo Content and Annealing on the Oxidation Behavior of Arc‐Melted Cr–xMo–8Si Alloys

The influence of Mo (10–40 at%) additions to Cr–8 at%Si is systematically studied by analyzing arc‐melted alloys in the as‐cast and annealed state. The oxidation resistance is tested by thermogravimetric analysis (TGA) at 1200 °C in air for up to 100 h. Samples are characterized by X‐ray diffraction, scanning electron microscopy, and wavelength‐dispersive X‐ray spectroscopy. The studied Cr–xMo–8Si alloy series shows a beneficial effect of Mo on the corrosion behavior. For all of the investigated Mo contents, no nitridation is observed and the oxide scale adhesion is improved. An increased amount of intermetallic A15 phase leads to the formation of a SiO2 scale beneath the Cr2O3 layer during high‐temperature exposure. The internal SiO2 layer inhibits further internal oxidation of the A15 phase. Uniform size and distribution of A15, benefits the formation of a duplex oxide scale. Cr–25Mo–8 at%Si, shows the most promising oxidation behavior. The TGA data follows the paralinear law, with both the growth rate, kp, and volatilization rate, kv, of Cr2O3 being reduced by adding 10–25 at% Mo. A binary Cr/Mo–Si phase diagram is generated in order to determine accurate annealing conditions and estimate the stability range of the metastable σ phase.

Localized corrosion characteristics of Al-Mg-Si aluminum alloy with aging time and pre-delayed aging condition

The effects of single aging, delayed aging and pre-delayed aging treatment on the corrosion resistance of Al-Mg-Si alloy were studied by scanning Kelvin probe force microscopy (SKPFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), three-dimensional X-ray tomography (3D-XRT), confocal laser scanning microscopy (CLSM) and electrochemical measurements. The surface potentials of Al(MnFe)Si, Mg2Si, and Si-rich remnant phases are determined, identifying Al(MnFe)Si phase as the crucial cathodic site for corrosion initiation, and the increase in surface potential implies an accelerated corrosion rate after immersion. The intergranular corrosion susceptibility of the alloy is predominantly influenced by the microstructure caused by aging conditions. The factors affecting corrosion resistance are summarized as (i) adjustment of electrochemical reaction activity by controlling the area fraction of Al(MnFe)Si phase, (ii) the spacing of grain boundary precipitates (GBPs), and (iii) the width of the precipitation-free zone (PFZ). The delayed aging (DA) sample exhibits inferior corrosion resistance due to the continuous GBPs and extended sub-grain boundaries corrosion propagation paths. The pre-delayed aging treatment successfully mitigates the corrosion degree of DA by widening the GBPs spacing and narrowing the PFZ width. This suggests that pre-aging treatment is a potent strategy for enhancing corrosion resistance without compromising the alloy's strength.

Thermodynamic assessment of the Cr–Si binary system

A thermodynamic evaluation of the Cr–Si system was performed concerning the latest experimental phase diagram and with the aid of first-principles calculations. The thermodynamic parameters for the Gibbs energy of pure Cr were modified based on the new experimental value of 1861 °C for the melting point of pure Cr, which was previously reported as 1907 °C in the SGTE database. The Gibbs energy descriptions of the Cr3Si and Cr5Si3 phases were revised using Cr3(Cr,Si)- and (Cr,Si)5Si3-type two-sublattice models to reproduce the latest experimental results of their solubility composition ranges, that is, Cr3Si extending toward the Cr-rich side and Cr5Si3 extending toward the Si-rich side from the stoichiometry. The CrSi and CrSi2 phases were considered line compounds with no solubility range, and the solubility of Cr in the Si phase was ignored. A set of self-consistent thermodynamic parameters for the Cr–Si system was obtained using the CALPHAD technique. The phase diagrams calculated using the optimized parameters showed reasonable agreement with the latest phase equilibrium data and thermodynamic property data in the literature, including the enthalpy of mixing, formation enthalpy, and chemical potential diagrams of Cr and Si in the equilibrium phases.

Fabrication of thin silicon flakes through dealloying from laser directed energy deposition Ca-Si alloys

Abstract In this study, thin silicon flakes were fabricated through dealloying from laser directed energy deposition (LDED) Ca-Si alloys, and the solidification mechanism of the lamellar eutectic microstructure was studied. With 1200 W laser power and 450 mm/min scanning speed, the LDED Ca-Si alloys have a fine lamellar eutectic microstructure and are easily separated from copper substrates. After dealloying in the diluted HCl solution for 6 h, the thin silicon flakes ranging in thickness from 100 nm to 0.5 μm were obtained. The formation of the thin flakes was attributed to fine lamellar Si phases in precursor alloys. The rapid solidification of laser processing could refine the microstructure, especially Si phases, and improve the chemical homogeneity of the material. Combining laser processing and dealloying, a cost-effective and scalable strategy was devised to fabricate fine powder from a laser processing optimized microstructure.

Effect of local loading on microstructure and enhanced mechanical property of large complex castings prepared by Al–Si–Fe–Mn–Mg–Cu alloy during squeeze casting

Flywheel shells with a complex structure and large wall-thickness difference, as key components in heavy trucks, serve to connect the engine and transmission. Formability and mechanical performance control of such components should be taken into consideration. In this work, an Al–Si–Fe–Mn–Mg–Cu alloy was used to manufacture the flywheel shell via squeeze casting. The role of local loading on microstructure and mechanical property at thick-walled positions was investigated. Furthermore, the effect of the squeeze casting specific pressure and heat treatment on the microstructure and mechanical property of the Al–Si–Fe–Mn–Mg–Cu alloy flywheel shells was also analyzed. The results showed that at the thick-walled positions, local loading not only helped eliminate the solidification defects, but also refined the microstructure including α-Al grains and secondary dendrite arm spacing. With increasing the squeeze casting specific pressure from 24 MPa to 32 MPa, microstructure refinement and mechanical property enhancement of squeeze casting flywheel shells were obtained. After T6 heat treatment, the yield strength and ultimate tensile strength of flywheel shells were further increased to 261.8 and 318.4 MPa, respectively, owing to the formation of spherical eutectic Si phases and nano-sized β'', Q and S precipitates.

Effect of 0.5 at. % Cu addition on the crystallization behavior and soft magnetic properties of Fe83B11C1Si2P3 alloy

In order to gain insight into how the addition of Cu element affects the crystallization mechanism of amorphous nanocrystalline alloys and soft magnetic properties, the crystallization behavior of (Fe0.83B0.11Si0.02P0.03C0.01)100-xCux (x = 0 and 0.5) amorphous ribbons was investigated based on kinetic and thermodynamic behavior under non-isothermal and isothermal annealing conditions. The results show that under non-isothermal annealing conditions, the Cu0.5 amorphous ribbon not only favors the formation of the amorphous structure, but also enlarges the temperature window for annealing and improves the thermal stability of the α-Fe(Si) phase. At the same time, the Cu0.5 amorphous ribbon shows slow kinetic and is insensitive to heating rate change during annealing treatment. Under isothermal conditions, the addition of Cu decreases the nucleation activation energy (En) and increases the growth activation energy (Eg). This further indicates that the nucleation of α-Fe(Si) grains is easier than the growth process, which is conducive to the formation of a homogeneous nanostructure and improves the soft magnetic properties of the alloy. Compared to Cu0 amorphous ribbon, it is also shown that the Cu0.5 amorphous ribbon changes the crystallization mechanism from diffusion-controlled one-dimensional to two-dimensional growth when the crystallization volume fraction x is 10–30 vol%. While three-dimensional growth become dominated when x is reaches 60 vol% for both ribbons. Therefore, the kinetics of crystallization as well as microstructure supports that the Cu0.5 ribbon is able to exhibit uniformly fine nanocrystalline structures. Further, the Cu0.5 nanocrystalline ribbon shows a higher Bs of 1.85 T and a lower Hc of 2.55 A/m, respectively, and the favorable (100) orientation of α-Fe(Si) grains formed after annealing is another factor to increase Bs.

Investigating the Microstructural and Mechanical Characteristics of Laser Additive‐Manufactured AlSi10Mg Specimens Through Experimental and Phase‐Field Modeling Approaches

Metal‐based additive manufacturing can make complicated parts that are complex or expensive to cast and process. Rapid cooling rates increase laser powder bed fusion (LPBF's) mechanical properties during manufacturing. The objective of this study is to examine the impact of process parameters in the L‐PBF technique on the characteristics of microstructure and mechanical properties, specifically, on the nanohardness influenced by Si segregation. The microstructures of the produced specimens are examined using field‐emission scanning electron microscopy and the analysis identifies the existence of bimodal equiaxed α‐Al grains, accompanied by Si phases located within their grain boundaries. In addition, the solidified sample exhibits the segregation of secondary precipitates, particularly Mg2Si, which results in enhanced mechanical properties. Both cellular walls and Si precipitates impede the motion and generation of dislocations, thereby influencing the overall behavior of dislocations. The examination of segregation at the top layer is conducted in a comprehensive manner, subsequently using energy‐dispersive X‐ray spectroscopy for analysis. The presence of Mg2Si, Al2MgSi2, and other phases in all samples is confirmed through X‐ray diffraction. The as‐built samples’ residual stress under different process conditions is also investigated. Additionally, the obtained microstructure is compared to a phase‐field model to forecast the evolution of the microstructure.

Effect of the Fe/Mn Ratio on the Microstructural Evolution of the AA6063 Alloy with Homogenization Heat Treatment Interruption

The casting structure of the AA6063 alloy contains intermetallic particles of β-Al5FeSi, which can result in the fragility of the cast pieces. However, with heat treatment, the β phase transforms from a needle or plate form into an intermetallic phase known as α, which resembles Chinese-script in its morphology. To analyze the effect of the ratio of Fe/Mn with different ratios of 0.5, 0.75, and 1, a heat treatment process is used with intermittent interruptions. The alloy is subjected to a temperature of 575 °C for 12 h to determine the microstructural evolution of the β-Al6FeMn and α-Al15(FeMn)3Si2 phases. This study used scanning electron microscopy to conduct point analyses and elemental mappings of the intermetallics found in the casting and heat treatment samples. Additionally, X-ray diffraction was employed to determine the stoichiometry of the present phases. The results indicated that the cast structure contains β-Al6FeMn and α-Al15(FeMn)3Si2 phases and that the β-Al6FeMn phase transforms into the α-Al15(FeMn)3Si2 phase upon completion of the heat treatment process. By using specific Fe/Mn ratios, the formation of the needle-shaped Al5FeSi phase in the casting structure of the alloy can be inhibited, leading to the precipitation of phases such as β-Al6FeMn and α-Al15(FeMn)3Si2 instead.

Towards high performance Al–Si–Fe alloy castings via rheo-diecasting: Effect of injection velocity and heat treatment on microstructure evolution and property

The mechanical properties and thermal conductivity of Al–Si–Fe castings must meet high requirements in the automobile, aerospace, and communication fields. Traditional high-pressure diecasting (HPDC) castings often have dendritic structures and pore defects that deteriorate their overall performance. Therefore, an advanced rheo-diecasting (RDC) technique assisted by a vibrating contraction sloping plate was proposed to address this problem. However, the process optimization strategy, microstructural evolution, and performance improvement mechanisms remain unclear. The influence of the injection velocity on the microstructure, mechanical properties, and thermal conductivity of the RDC tensile specimens was first investigated. A high-performance cover plate was fabricated via RDC using an optimized injection velocity. The results showed that when the injection velocity increased to 2.8 m/s, the porosity decreased to a minimum value, and the mechanical performance and thermal conductivity of the RDC tensile specimens reached their maximum values. Furthermore, spherical eutectic Si phases and nanosized Mg2Si precipitates for the RDC cover plate were observed after T6 heat treatment, which further improved the mechanical properties and thermal conductivity owing to Orowan strengthening and decreased lattice distortion, respectively. The ultimate tensile strength, yield strength, elongation, and thermal conductivity for the RDC cover plate were 358.2 MPa, 279.9 MPa, 12.5%, and 180.72 W/(m·K), respectively, which were higher than that of reported similar alloys. From engineering perspectives, this study had the application value for produce of high-quality RDC castings.

Evolution of interphase stress over a crack propagation plane as a function of stress relief heat treatments in a PBF‐LB/M AlSi10Mg alloy

AbstractIn this study, we compare the residual stress state in a laser powder bed fusion (PBF‐LB/M) AlSi10Mg alloy in the as‐built (AB) condition with that after two different heat treatments (265 °C for 1 h, HT1; and 300 °C for 2 h, HT2). The bulk residual stress (RS) is determined using synchrotron X‐ray diffraction (SXRD), and near‐surface profiles are determined using laboratory energy‐dispersive X‐ray diffraction (EDXRD). The EDXRD results do not reveal any notable difference between the conditions at a depth of 350 μm, suggesting that the machining process yields a comparable residual stress state in the near‐surface regions. On the other hand, the SXRD results show that HT1 is more effective in relieving the bulk RS. It is observed that HT1 reduces the RS state in both the aluminium matrix and the silicon network. In addtion, HT2 does not have a significant impact on relaxing the RS as‐built state of the matrix, although it does induce a reduction in the RS magnitudes of the Si phase. It is concluded that the heat treatment stress relieving is effective as long as the Si‐network is not disaggregated.

Effects of the synergistic addition of AlCrNiTi and Ce on the microstructure and mechanical properties of hypoeutectic Al-7Si alloy

A new strategy is proposed in this study to modify the microstructure of the Al-7Si alloy, which is widely employed in the aerospace and transportation sectors due to its lightweight, high specific strength, and specific modulus. The primary challenge of the Al-7Si alloy is its coarse microstructure, which undermines its mechanical properties. This research focuses on the effects of adding the AlCrNiTi master alloy and Ce to the Al-7Si alloy. The impact on both the microstructure evolution and the mechanical properties is examined, including analysis and discussion of the underlying mechanisms for refinement and strengthening. When the alloy was modified by 0.9 wt% of the AlCrNiTi master alloy and 0.1 wt% of Ce, there was a notable refinement of the α-Al phase, transforming it from a coarse dendritic structure to fine equiaxed grains. The addition of 0.9 wt% of the AlCrNiTi master alloy and 0.1 wt% of Ce can also reduce the secondary dendrite arm spacing (SDAS) to 5.9 μm. The eutectic Si phase underwent a significant transformation, changing from coarse flakes to fine granularity with rounded edges. Furthermore, CeSi2Ni2, Al3Ni intermetallic compounds, and nanoscale Al45Cr7 particles were observed in the modified Al-7Si alloy. Tensile tests showed that the addition of the inoculant in the Al-7Si alloy enhanced the ultimate tensile strength (UTS) from 173 MPa to 211 MPa and increased the elongation (El) from 7.9% to 14.1%.

Crystallography and Interface Structures in As-Arc Melted and Laser Surface-Remelted Aluminum–Silicon Alloys with and without Strontium Addition

The crystallography of the eutectic Al-Si microstructure in both unmodified and Sr (0.2 wt.%)-modified hypereutectic Al-20 wt.% Si alloys, processed via arc-melting and laser surface remelting, has been comprehensively characterized using transmission electron microscopy and electron diffraction. Although, under as-cast conditions, specific orientations between different planes of Al and Si, satisfying defined orientation relationships (ORs), have been investigated within the flake morphology, the rapid solidification induced by laser surface remelting results in a notable transformation from a flake morphology to nanocrystalline Si fibers dispersed in an Al matrix. Consequently, this transformation results in a mis-orientation of the interface between the eutectic Al and Si phases, preventing the formation of orientation relationships, thus promoting the formation of faceted interfaces exhibiting substantial lattice disregistry.

Effect of carbon nanotubes content on compressive properties and deformation behaviors of aluminum matrix composite foams

The incorporation of nano carbon reinforcement is a useful strategy to broaden the engineering applications of metal foams. In this work, carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composite foams (CNTs/Al composite foams) with different CNTs content are prepared by combining ball-milling technique with powder metallurgy method. The result shows that the appropriate content of CNTs can reduce the pore size, improve the circularity, and enhance the compressive properties. Especially, the 1.0 wt% CNTs/Al composite foams possess the optimal compressive properties of yield stress (7.90 MPa), plateau stress (8.75 MPa) and energy absorption capacity (5.19 MJ/m3), which have an enhancement of 23.24%, 98.41% and 84.70%, respectively. Composite foams undergo shear deformation throughout the quasi-static compression process, and the failure mode performs as the brittle mode combined with ductile mode. Meanwhile, the incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase, provide more nucleation sites, and significantly refine the pore size. It is confirmed that the CNTs in composite foams contribute the grain refinement and the formation of micro stacking faults, making the mechanical properties of CNTs/Al composite foams outperform the counterpart of Al-Si foams. Moreover, due to the weak interfacial reaction, the low content of aluminum carbide is formed, which can promote the load transfer between CNTs and Al. The present finding provides a theoretical and practical design strategy to the future preparation of CNTs/Al composite foams.

Experimental study of millisecond pulse laser ablation biased silicon-based PIN photodiodes

The investigation of the highest surface temperature and damage region of silicon-based photodiodes (PIN) was conducted through irradiation with millisecond (ms) pulse lasers. The convex spots on the surface of the biased photodiode were observed to be diminished by a millisecond pulse laser for the first time. The experimental results presented herein demonstrate the presence of a bump, even in cases where the maximum surface temperature of the damaged area does not exceed the melting point. The mechanism underlying this phenomenon was elucidated through the integration of simulation and experimentation in our study. The irradiation of silicon-based semiconductor detectors with lasers generates internal Joule heat, causing the temperature at the junction depth to initially reach the melting point. The expansion resulting from the Si phase transition induces outward pressure on Si3N4, leading to the eventual formation of a convex morphology. The findings of our study present a novel approach to enhance the security of photodetectors.

Microstructural origin of high strength and high strain hardening capability of a laser powder bed fused AlSi10Mg alloy

Compared to a cast AlSi10Mg alloy, a laser powder bed fused (LPBF) AlSi10Mg alloy shows superior yield strength and strain hardening capability. However, the underlying microstructure origin has not been comprehensively understood. In this work, the microstructural evolution of an LPBF AlSi10Mg alloy during tensile deformation was investigated. Synchrotron X-ray diffraction characterization shows that both stress and strain exhibit significant partition between an Al phase and a Si phase upon tensile deformation. This leads to a significant strain gradient between those two phases, which is evident by the high density of dislocations in the cell boundaries of the deformed alloy. The strain gradient results in long-range internal stress, also known as back stress, in the cell boundaries, and in turn leads to enhanced strength and strain hardening in the LPBF AlSi10Mg alloy. Quantitatively analyses via loading-unloading-reloading tests show that during the tensile deformation, the back stress contributes 135 MPa to the yield strength of the alloy, which continuously increases with increasing the strain beyond the yielding point. This work illuminates the microstructural origin of the back stress in the LPBF AlSi10Mg alloy, i.e. the back stress arises from the stress/strain partition between the Al and Si phases in the cellular structures, and the back stress leads to significant strengthening of the alloy upon tensile deformation. This work may also provide guidance for manipulating the mechanical properties of additively manufactured Al-Si alloys for specific application needs.

Enhancing the strength and structure of Al–Si alloys for biomedical applications through the addition of Sr and Zr grain refiners on secondary AlSi7Mg aluminum alloys

The biomedical industry needs Aluminium alloys with superior corrosion resistance properties for limited applications. The use of Al–Si alloys is often seen as non-bio-compatible alloys due to their lower corrosion resistance properties. The present study aims to enhance the properties of such Al–Si alloys through modification of the Si phases with Strontium (Sr) and Zirconium (Zr) through grain size modification. The present study included the preparation of an Al–Si aluminium alloy utilizing a mixture of different scraps. To refine the grain structure, variable concentrations of Sr and Zr grain refiners were added to the alloy using a stir-casting process. The qualities, including porosity, density, tensile strength, yield strength, and hardness, were assessed according to ASTM standards. The grain size and distribution of intermetallic compounds were investigated by performing a microstructural examination using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, to determine the impact of Sr and Zr. The results demonstrate that the inclusion of Sr and Zr grain refiners effectively enhances the grain structure, leading to enhanced microstructural and mechanical properties of the secondary aluminium alloys. This study contributes valuable insights into optimizing the grain refining process for secondary aluminum alloys, offering potential advancements in their industrial applications, particularly in the biomedical industry, where the demand for high-performance biocompatible aluminum materials is steadily increasing.