Al3Zr Particles Research Articles

Dynamic recrystallization mechanisms and microstructure evolution of a novel Al-Zn-Mg-Cu-Zr alloy by isothermal compression

The dynamic recrystallization (DRX) behavior and microstructure evolution of a novel Al-Zn-Mg-Cu-Zr alloy was investigated by isothermal compression tests at temperature of 350–470 °C and strain rate of 0.0001–1 s−1. The results showed that the flow behavior revealed typical dynamic recovery (DRV) characteristics at a high strain rate (1 s−1), while exhibited a DRX shape when the strain rate decreased. The critical strains (εc) of the DRX decreased with the decrease of strain rate or the increase of deformation temperature. A low temperature was conductive to precipitation behavior, the coarse precipitates and dispersed Al3Zr particles would pin the dislocations and substructures, which inhibit the DRX process. The DRX mechanism of the Al-Zn-Mg-Cu-Zr alloy was dominated by continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) during the hot deformation process, upon increasing the temperature and decreasing the strain rate, there was a transition point of DRX mechanism from DDRX to CDRX. Moreover, the linear relationship between the Zener-Hollomon (Z) parameter and DRX grain size was established for the further exploration of the transition of the dominant DRX mechanism.

Analysis of Ni-Cu Interaction in Aluminum-Based Alloys: Hardness, Tensile and Precipitation Behavior.

The present work was aimed at quantifying the effects of Ni addition in the range of 0-4% together with 0.3%Zr on the hardness and the tensile properties, volume fraction of intermetallics, and changes in size and distribution of phase precipitation in Sr-modified Al-9%Si-2%Cu-0.6%Mg cast alloys. The study was mainly carried out using high-resolution FESEM and TEM microscopes equipped with EDS facilities. Samples were solidified at the rate of ~3 °C/s and examined at different aging conditions. The investigations are supported by thermal analysis carried out at a solidification rate of ~0.8 °C/s. The results revealed that the main compositions of the Ni-based phases are close to Al3(Ni,Cu), Al3CuNi, and Al3Ni. An Al3Ni2Cu2 phase was also detected in the 4%Ni alloy. The Cu-Ni phases were observed to precipitate, covering the surfaces of pre-existing primary Al3Zr particles. The TEM analysis indicated the magnitude of the reduction in both size and density of the precipitated Al2Cu phase particles as the Ni content reached 4%, coupled with a delay in the transition from coherent to incoherency of the Al2Cu precipitates.

Strength and plasticity improvement induced by strong grain refinement after Zr alloying in selective laser-melted AlSiMg1.4 alloy

In order to enhance the mechanical properties of the selective laser-melted (SLM) high-Mg content AlSiMg1.4 alloy, the Zr element was introduced. The influence of Zr alloying on the processability, microstructure, and mechanical properties of the alloy was systematically investigated through performing microstructure analysis and tensile testing. It was demonstrated that the SLM-fabricated AlSiMg1.4−Zr alloy exhibited high process stability with a relative density of over 99.5% at various process parameters. Besides, the strong grain refinement induced by the primary Al3Zr particle during the melt solidification process simultaneously enhanced both the strength and plasticity of the alloy. The values for the yield strength, ultimate tensile strength, and elongation of the SLM-fabricated AlSiMg1.4−Zr were (343±3) MPa, (485±4) MPa, and (10.2±0.2)%, respectively, demonstrating good strength− plasticity synergy in comparison to the AlSiMg1.4 and other Al−Si-based alloys fabricated by SLM.

Hot deformation mechanism of a rapidly-solidified Al–Zn–Mg–Cu–Zr alloy

This study systematically investigates the flow behavior of 7050 aluminum (Al) alloy produced via spray forming and subjected to a proposed pretreatment through thermal compression tests. The experimental findings reveal that the peak stress increased with decreasing deformation temperature or increasing strain rates. The parameters in the Arrhenius constitutive model were determined and verified by experimental results for spray formed (SFed) 7050 Al alloy. Hot deformation activation energy of the SFed 7050 Al alloy (147.38 kJ/mol) is notably lower than that of cast Al–Zn–Mg–Cu–Zr alloys, which is attributed to factors such as fine grains, low segregation, pores, and dispersed Al3Zr induced by pretreatment. Furthermore, processing maps have been constructed at various strains, revealing optimal stable deformation conditions at 300–450 °C/0.001–0.15s−1 and 425–450 °C/0.2–1s−1. Microstructural analysis of deformed samples highlights the critical role of dynamic recrystallization in influencing the stable and unstable areas of the alloy, which may be activated by high temperature and slow strain rate. The hot deformation mechanism of the SFed Al alloy is governed by interactions among η-Mg(Zn,Al,Cu)2 precipitates, dispersed Al3Zr particles, dislocation structures, and (sub-)grain boundaries.

Effect of Sc/Zr ratio on superplastic behavior of ultrafine-grained Al–6%Mg alloys

Al–6%Mg-Sc-Zr alloys with a combined Sc and Zr ratio of 0.32 wt% make up the focus of this research. The content of Sc and Zr varied with an increment of 0.02%. Their ultrafine-grained (UFG) microstructure was formed with Equal Channel Angular Pressing (ECAP). Superplasticity tests were performed at temperatures ranging from 300 to 500 °C and at a strain rate varying between 3.3·10−3 and 3.3·10−1 s−1. The values of strain hardening factor (n), strain rate sensitivity factor (m), and superplastic deformation threshold stress (σp) were determined. The microstructure and failure patterns of the alloys post superplasticity tests were studied. The effect of the Sc/Zr ratio on the superplastic behavior, cavitation fracture and dynamic grain growth of UFG Al–6%Mg alloys was investigated. The satisfiability of Hart's criterion for calculating uniform deformation value under superplastic conditions was verified. Grain boundary sliding and intragranular deformation make comparable contributions to superplastic flow in the UFG aluminum alloys under study. Al–6%Mg-0.20%Sc-0.12%Zr (Sc/Zr = 3.3 at.%) and Al–6%Mg-0.18%Sc-0.14%Zr (Sc/Zr = 2.8 at.%) alloys exhibit the highest superplasticity. Shown that changes in the Sc/Zr ratio affect the precipitating mechanism, spatial distribution and composition of the precipitating particles Al3(ScxZr1-x). The optimal Sc/Zr ∼2.6–3.3 (at.%) ratio for the Al–6%Mg alloy corresponds to an Al3(Sc0.5Zr0.5) and Al3Sc precipitated particles. The large Al3Zr particles formed through the discontinuous precipitation mechanism was detected at Sc/Zr < 1 (at.%).

Study on Quench Sensitivity during Isothermal Treatment of 7A65 Aluminum Alloy.

The quenching sensitivity of 7A65 aluminum alloy was investigated using interrupted quenching experiments. The time-temperature transformation (TTT) and time-temperature performance (TTP) curves of the alloy were determined. The results indicate that the nose temperature is about 320 °C and the quenching sensitivity temperature range is from 240 °C to 360 °C. During the isothermal treatment, the supersaturated solid solution resolves to the equilibrium phase of η (MgZn2), and the precipitation rate is the largest at about 320 °C. Through transmission electron microscope (TEM) observation and X-ray diffraction (XRD) tests, it was found that with the extension of the isothermal holding time, the originally dispersed η' phase gradually decreases until disappear, and the number of η phase increases and gradually grows up at the grain boundary or around the Al3Zr particles. The rod-like η phase at the grain boundary is distributed from discontinuous distribution to chain-like continuous distribution, and the precipitation free zone (PFZ) is gradually generated and widened as the holding time is extended. At the nose temperature, the driving force of nucleation is high, and the diffusion rate is fast, which promotes the precipitation and growth of η phases. The coarse η phase weakens the mechanical properties. According to the results, it is recommended to increase the cooling rate at the sensitivity temperature range to reduce the precipitation of the η phase and decrease the quenching cooling rate from solution temperature to 360 °C to reduce residual stresses in the components.

The heterogeneous precipitation behavior of Al-Zn-Mg-Cu alloy was studied by high-throughput experiment based on end-quenching technology

Based on the quenching experiments and in combination with electrical conductivity measurements and microstructural characterization, the non-uniform precipitation behavior of the 7055 alloy was investigated. The study revealed that as the quenching rate decreased from 20.8 °C/s to 2.25 °C/s, the electrical conductivity increased from 27.8 %IACS to 30 %IACS, and both the types and nucleation sites of quenching-induced precipitates increased. The favorable nucleation sites for the precipitation were identified in the following sequence: high-angle grain boundaries (HAGBs), low-angle grain boundaries (LAGBs), non-coherent Al3Zr particles, dislocations, and coherent Al3Zr particles. The sequence of non-uniform precipitate formation included η, S, T, and Y phases. With the reduction in quenching rate, the η phase successively precipitated on HAGBs, LAGBs, non-coherent Al3Zr particles, and coherent Al3Zr particles. At a quenching rate of 10.5 °C/s, not only was the S phase observed to precipitate at high-density dislocation subgrains (SGs), but also the T phase was observed to precipitate at the non-coherent Al3Zr particles and subgrain boundaries (SGBs). When the quenching rate was further reduced to 2.7 °C/s, the precipitation of the Y phase was observed at SGs dislocations, and simultaneously, the precipitation of the η and T phases was observed on the coherent Al3Zr particles within the SGs.

Crack-free high-strength AA-7075 fabricated by laser powder bed fusion with inoculations of metallic glass powders

High-strength aluminum alloy is widely utilized in aerospace field. The primary thrust of this work was to overcome the issue of hot cracking of AA-7075, which occurs during laser powder bed fusion (LPBF) processing. By employing an innovation inoculation treatment with 5 wt % Zr50.7Cu28Al12.3Ni9 metallic glass (MG) powders, highly dense (relative density >99.2 %) and crack-free composite specimens of AA-7075/MG were successfully fabricated within a broad printing range. The as-printed AA-7075/MG composite specimens exhibited a uniform microstructure with the fine equiaxed grains and the crack mitigation was attributed to the grain refinement, which decreased from 9.9 μm to 0.564 μm after addition of MG powders. The inoculation treatment of MG powders triggered the in-situ formation of Al3Zr particles on the one hand, promoting the formation of fine equiaxed grains with random orientation. On the other hand, in-situ formed nano-sized amorphous particles formed due to the high glass-forming ability of Zr-based MG and rapid cooling rate during LPBF process could strengthen the alloy. The as-printed AA-7075/MG composite specimens exhibited a compressive strength exceeding 1.5 GPa. Meanwhile, it exhibited the highest ultimate tensile stress and yield strength of 513 MPa and 488 MPa, respectively, with an elongation of over 9 %. The excellent mechanical properties are ascribed to a synergistic combination of grain boundary strengthening, precipitation strengthening induced by Al3Zr nanoparticles, solid-solution strengthening, and the effective obstacle of dislocation motion by the nano-sized amorphous particles. The current work presents a novel and cost-effective approach to producing crack-free, high strength aluminum engineering components using LPBF.

Microstructure, Hardening, and Mechanical Properties of Hypoeutectic Al–Ce–Ni Alloys with Zr and Zr + Sc Additions and the Effect of Ultrasonic Melt Processing

Ternary Al–Ce–Ni alloys have a potential in the manufacture of automotive and airspace components, as well as in replacing traditional aluminum alloys in high‐temperature applications, which is determined by the formation of fine and thermally stable Al11Ce3 and Al3Ni eutectic. Herein, the microstructure and mechanical properties of a hypoeutectic Al4Ce2Ni alloy using Zr and Zr + Sc additions combined with ultrasonic melt processing and dispersion hardening are improved. As a result, the grain structure of the as‐cast alloys is significantly refined and the annealing at 350 °C leads to a considerable hardening effect, especially in the alloys with Zr + Sc additions (doubling the hardness). Al3Zr and Al3(Zr,Sc) coherent particles are identified as hardening nanoprecipitates. The compressive mechanical testing at room and elevated temperatures shows that the additions of Zr and Zr + Sc improve the strength with the additional increase caused by ultrasonic melt processing.

The effects of heat treatment on the extrusion-induced inhomogeneity of spray-formed aluminum alloy 7055

The local inhomogeneity along the thickness direction of the extruded plate of spray-formed aluminum alloy 7055 were investigated. The thermal extrusion process was simulated by using DEFORM-3D software to understand its formation mechanism. In order to reduce the extrusion-induced inhomogeneity and improve the mechanical properties, the evolution of the secondary phase during different heat treatments and its influence on the peak aged hardness and tensile strength of the alloy were emphatically analyzed. The results show that the strain rate and temperature during the thermal extrusion process tend to decrease from the surface to the center, which leads to the local inhomogeneity of the microstructure and properties in the thickness direction. Such inhomogeneity can be reduced by heat treatments combining long-time or slow-heating solution treatments (F2 and F3) with peak ageing at 120 °C, due to similar content of S (Al2MgCu) phase after solution treatment and η′ phase (peak-ageing) in different regions of the alloy. The alloy solution treated with a slow heating rate (F3) and then peak aged shows highest hardness and tensile strength, because the slow heating process during the solution treatment promotes the precipitation of Al3Zr particles, and there are less S (Al2MgCu) phases after solution treatment which is conducive to the η′ phase precipitation during the subsequent aging process.

Development of microstructure of asymmetrically rolled AA3003 aluminium sheets with Zr addition

Asymmetric rolling is a method of severe plastic deformation, which can produce large volumes of deformed material and is easy to implement for industrial use. Asymmetric rolling with different circumferential velocities of rolls gives rise to intense plastic shear strains, resulting in grain refinement and improving mechanical properties. An aluminium alloy from AA3003 series enhanced by 0.16 wt% Zr was produced by twin-roll casting in industrial conditions. A part of specimens was annealed at 450∘C in order to precipitate fine dispersion of Al3Zr particles, which may enhance recrystallization resistance at elevated temperatures. Materials were subjected to cold rolling and to asymmetric rolling in several steps. Both methods result in a substantial elongation and fragmentation of grains. The grain refinement is more distinctive after asymmetric rolling. During isochronal annealing Vickers microhardness of materials decreases. The main drop occurs in the asymmetrically rolled material between 400 and 450∘C. In the annealed material the main drop connected with recrystallization is shifted by 50∘C to higher temperatures due to the presence of Al3Zr particles. Recrystallization occurs in the cold-rolled material between 450 and 500∘C. The imposed deformation by rolling is lower in this specimen and hence the driving force for recrystallization is also lower than in the asymmetrically rolled material. After recrystallization, the grain size of both cold-rolled and asymmetrically rolled materials is comparable. However, grains are still elongated in the rolling direction.

Effect of Homogenization and Precipitation Heat Treatments on Localized Corrosion of Al-Mn-Zr Alloy with Fe Impurity

This study aimed to enhance the corrosion resistance of an Al-Mn-Zr alloy containing Fe impurities by using heat-treatment processes. Three processes were implemented to distribute intermetallic particles uniformly, promote Al6(Mn, Fe) and Al3Zr particle formation, and eliminate Fe and Zr segregation. Increasing the amount of Al6(Mn, Fe) reduced the galvanic effect between the Al matrix and Al3Fe particles, leading to improved localized corrosion resistance. Al3Zr promoted smaller grain size by preventing recrystallization. Microstructure analysis confirmed the inhibitory effect on grain growth and the promotion of Al6(Mn, Fe) and Al3Zr particle formation. The effect of grain size on galvanic corrosion was evaluated through corrosion simulation. Furthermore, the improved localized corrosion resistance was evaluated through electrochemical and immersion tests. Consequently, the designed heat-treatment process significantly improved the localized corrosion resistance of the Al-Mn-Zr alloy with Fe impurities. These results demonstrate the effectiveness of the used heat-treatment processes in improving the corrosion resistance of the alloy.

Achieving high strain rate superplasticity in an Al-Cu-Li alloy processed by thermo-mechanical processing

In order to obtain high strain rate superplasticity, it is usually necessary to prepare fine-grained aluminum alloy by severe plastic deformation such as equal channel angular pressing. A traditional thermo-mechanical processing was exploited to prepare fine-grained Al-Cu-Li alloy with 3.1 μm grains. A maximum elongation of 1220% was obtained at a high strain rate of 1 × 10−2 s−1 and 490 °C. The high-stain rate superplasticity is attributed to the existence of stabilized fine grains and nano-scaled Al3Zr particles which inhibit the dynamic growth of grain. Furthermore, the calculated deformation activation energy and m values suggest that the grain boundary sliding mechanism is active.

Crack-free and high-strength AA2024 alloy obtained by additive manufacturing with controlled columnar-equiaxed-transition

Laser powder bed fusion (LPBF) of high-strength Al alloys is challenging due to the formation of both hot and cold cracks. In the present work, highly dense and crack-free AA2024 samples could be additively manufactured via inoculation treatment of Zr-based metallic glass (MG) powders. The columnar grains in the LPBF-fabricated AA2024 alloy were significantly refined and almost completely transformed to the equiaxed grains with a bimodal grain size distribution consisting of ultrafine grains with a size smaller than 1 μm and relatively coarser grains. The grain refinement can be associated with the formation of Al3Zr particles, serving as the heterogeneous nucleation sites for the α-Al matrix. Complete routes for columnar-equiaxed-transition (CET) have been revealed by tailoring the concentration of nucleation particles and solidification conditions. CET occurs both at the melt pool boundary due to the sufficiently high concentration of Al3Zr particles and at the topmost of the melt pool due to the heterogeneous nucleation driven by constitutional undercooling. Between these two regions, columnar grains epitaxially grow with orientations determined by the thermal gradient. The as-built Zr-based MG inoculated AA2024 specimens are robust in healing hot cracks due to a more tortuous propagation path of cracks for equiaxed grains. The as-fabricated AA2024/5% MG specimens exhibit a high ultimate tensile strength of 531 MPa due to crack elimination and grain refinement, surpassing most of the reported values for the LPBF-fabricated AA2024 alloy inoculated with other inoculated powders. The present work could provide a novel inoculation agent to fabricate high-strength Al alloys and the CET can be used to precisely control the grain morphology.

Achieving superior dispersion-strengthening effect in an AA5xxx Al-Mg-Mn alloy by mico-alloying

5xxx Al-Mg based alloys are widely applied as non-heat-treatable alloys. In this work, we designed a dispersion-strengthening Al-4Mg-1Mn-0.3Fe-0.2Si-0.2Zr-0.2Cr (wt.%) alloy. By applying ramp heating and 400 °C isothermal aging, a significant dispersion-strengthening effect through the formation of various types of dispersoids was achieved. Detailed scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis revealed the precipitation behaviors of nanoscale Mn-rich dispersoids and Al3Zr nanoparticles during heat treatments. As a result, an increment of 48 MPa in yield strength was obtained compared with the reference 5182 alloy. Meanwhile, the modified alloy shows a good heat resistance at 400 °C with little loss of yield strength until 200 h of heating. This has been attributed to the further precipitation of Al3Zr particles which counteracts the coarsening of Mn-rich dispersoids. Moreover, the addition of peritectic element Cr was found to significantly promote the precipitation of Al6(Mn,Fe,Cr) in dendritic center regions, thus improving their global distribution across dendrite arms. The presence of dense dispersoids can also improve the recrystallization resistance of the deformed alloy during annealing, thus retaining the deformation fiber structure and significantly retarding the recrystallization behavior. This research demonstrates an effective strategy to develop high-performance 5xxx series alloys strengthened via dispersoids.

Eutectic, precipitation-strengthened alloy via laser fusion of blends of Al-7Ce-10Mg (wt.%), Zr, and Sc powders

Laser powder-bed fusion was used to create an Al-7Ce-10Mg-0.71Zr-0.23Sc (wt.%) alloy, using hypoeutectic Al-7Ce-10Mg (wt.%) pre-alloyed powder blended with either elemental Zr and Sc powders (∼20 µm in size), or pre-alloyed, concentrated Al-10Zr and Al-10Sc (wt.%) powders (comprised of 1-5 µm Al3Zr or Al3Sc particles embedded in a <45 μm Al-rich matrix). The effects of process parameters and powder selection on the homogeneity of the as-fabricated microstructure were investigated via metallography and compared to predictions from a simple numerical model describing the dissolution of Zr powders in the melt pool during printing. Both experiments and model show that decreasing scan speed leads to greater dissolution of Zr and Sc, but remelting has no significant effect. The samples produced with Al-10Zr and Al-10Sc powder additions show greater amounts of Zr and Sc dissolution than those produced with elemental Zr and Sc additions, because of the smaller size (5 µm for prealloyed vs. 20 µm for elemental) and lower melting point (1580 and 1320°C for Al3Zr, Al3Sc vs. 1850 and 1541°C for Zr, Sc) of the dissolving species. The alloys fabricated with prealloyed powders display larger amounts of very fine grains (1-2 µm) nucleated by primary L12 Al3(Zr,Sc) precipitates, and a clear hardening response during aging, consistent with supersaturated Zr and Sc forming a high number density of secondary L12 Al3(Zr,Sc) nanoprecipitates.

Influence of Cu content on the hardenability of Al-xCu-1.1Li alloys

The influence of Cu content (3.7 wt%, 4.1 wt% and 4.3 wt%) on the hardenability of Al-xCu-1.1Li alloys was evaluated through a novel end quenching method by using cold-rolled thin sheets combined with strength measurement after subsequent T8 aging. The yield strength of all three aged alloys decreases with the increase of the distance away from the quenching end. The quenching depth decreases with the increase of the Cu content, which was described by the distance of 95% strength retention value of the samples at the quenching end. The intragranular coarse Cu-enriched phase particles formed during the end quenching process impede the precipitation of T1 precipitates and then lead to the strength reduction. The higher Cu content alloy with more and larger Cu-enriched particles inside the grain causes the more decrease in T1 precipitation, which consequently leads to more reduction in strength. The alloy with higher Cu content therefore has lower quenching depth. The coarse Cu-enriched grain boundary phase particles cause the solute depletion around the grain boundary and create PFZ. Based on the time-temperature-properties (TTP) curves, the quench sensitivity increases and the stability of the supersaturated solid solution of the alloy decreases with the rise of the Cu content. Additionally, the coarse Cu-enriched particles within the grain might be coarse Al2Cu particles, which tend to nucleate at the Al3Zr particles.

Laser powder bed fusion of Al–Mg–Zr alloy: Microstructure, mechanical properties and dynamic precipitation

A Sc-free and high-plasticity Al-4.8Mg-1.6Zr aluminum alloy was densified via laser powder bed fusion. The microstructure features a typical bimodal grain structure, with abundant L12-Al3Zr particles about 100 nm distributed. The yield strength (YS) of 449 ± 4 MPa, ultimate tensile strength (UTS) of 449 ± 5 MPa, and the elongation to failure (EL) of 15.1 ± 1.9% are obtained after peak aging. In addition to solid solution strengthening, grain boundary strengthening and nanoparticle strengthening, the long-range stacked ordered 9R phase associated with high content Mg and Zr also contributes to strengthening. Besides, the difference in strain distribution between coarse and fine grain zones causes deformation-induced hardening. Low-temperature dynamic precipitation is observed in this Al–Mg–Zr alloy for the first time. The deformation-induced hardening and dynamic precipitation improve the strain-hardening capability, consequently delaying necking instability. After peak aging treatment, the number of Al3Zr particles with strong high-temperature stability increases, inhibiting grain coarsening and enhancing the precipitation strengthening effect. The excellent strength-ductility trade-off of the printed Al–Mg–Zr without expensive Sc element gives it a broad application prospect in economical and large-scale additive manufacturing.

A hypoeutectic Al-Ni-Mg in situ composite processed by wire-arc additive manufacturing: Phase evolution and mechanical behavior

The advent of novel processing technologies such as wire-arc additive manufacturing, distinguished by high cooling rates, requires the development of adapted feedstock materials. Here, the advantageous solidification behavior of an Al-Ni-Mg alloy was employed, whereby hot cracking can be omitted through dominant amounts of eutectic solidification. Specimens of this new alloy processed by wire-arc additive manufacturing were investigated in-depth to study the phenomena of microstructure formation and the phenomena governing the mechanical characteristics. For this purpose, the deposits were characterized using X-ray diffraction, scanning and transmission electron microscopy, differential scanning calorimetry, hardness, tensile and fracture toughness testing. Results of microstructure investigations were compared to thermodynamic calculations. The microstructure consists of α-Al/Al3Ni colonies separated by α-Al intercolony regions. Minor amounts of Al3Zr and Mg2Si second phase particles were observed. Mechanical characterization reveals ductile failure after pronounced hardening and substantial isotropic fracture toughness. The mechanical properties are discussed based on the prevalent microstructural characteristics. The presented results provide the basis for future, novel and advanced alloys dedicated for their use in wire-arc additive manufacturing.

Effect of Sc and Zr on Precipitation Behaviour of Wrought Al- Bronze

Aluminium bronze doped with Sc and Zr were prepared by casting followed by cold-rolling with varied degrees of deformation. Then, the cold-rolled samples were aged for one hour at various temperatures, isochronally up to 500°C and isothermally at 300°C and 350°C up to four hours respectively. To better understand the precipitation behavior of Al-bronze with Sc and Zr additions, microhardness and electrical resistivity of aged alloys were investigated. The formation of copper aluminates precipitate resulted in a significant hardening improvement in aged alloys particularly at 300 °C. The addition of both Sc and Zr improved the thermal stability of the aged alloys by forming Al3Sc and Al3Zr precipitates. Sc, on the other hand, had proven to be more effective at improving aging behaviour of Al-bronze alloy. Electrical resistivity was also observed to increase with increasing aging temperature, then decrease slowly due to the production of fine precipitates and coarsening of this precipitate by over ageing, respectively. The DSC investigation supported the precipitation response by demonstrating the varied peaks of the heating curve at various temperatures. The reflectance spectroscopy study revealed that the addition of Sc and Zr exhibited greater optical response owing to grain refinement. Optical microscopy of cold rolled samples exhibited multiple phases of elongated grain along the rolling direction, and Sc and Zr additions were capable of refining alloy grains by precipitation of primary Al3Sc and Al3Zr particles formed as heterogeneous nuclei during solidification. In the meantime, recrystallization and grain growth development were induced in Al-bronze by ageing at 500°C for an hour. During ageing treatment, the production of secondary Al3Sc and Al3Zr precipitates efficiently inhibited the mobility of dislocation and sub-grain boundaries, preventing the Sc and Zr doped alloys from recrystallization.