Constituent Phases Research Articles

Temperature dependences of phase composition, densification, and thermal/chemical stability of Sr0.5Zr2(PO4)3-Nd0.5Sm0.5PO4 composite ceramics for nuclear waste form

A kind of Sr0.5Zr2(PO4)3-Nd0.5Sm0.5PO4 (hereinafter SrZP-Nd0.5Sm0.5PO4) composite ceramics was prepared through a one-step microwave sintering technique, where Sr, Nd, Sm were simulated for fission products and minor actinides (MA). The crystal structure and morphology of constituent phases were systematically characterized by XRD, TEM, and SEM techniques. The temperature dependent phase analysis results of SrZP-Nd0.5Sm0.5PO4 composite ceramics illustrate that with evaluating temperature monazite structure formed primarily, and the SrZP phase formed subsequently. With the temperature rising further, the monazite phase finally transformed into Nd0.5Sm0.5PO4 monazite solid solution. XRD refinement and TEM measurements are used to verify the crystal structures of the as-prepared SrZP and Nd0.5Sm0.5PO4 phases in the composite ceramics. The dependence of densification behaviors on temperature shows that the distinct densification of the SrZP-Nd0.5Sm0.5PO4 composite ceramics occurs in the temperature range of 950 °C to 1000 °C, and the relative density reaches 97.7 % at 1050 °C. TG-DSC tests show that the SrZP-Nd0.5Sm0.5PO4 composite ceramics exhibit excellent thermal stability at high temperatures. And SrZP-Nd0.5Sm0.5PO4 composite ceramics possess outstanding chemical stability, whose normalized leaching rate of Sr, Nd, and Sm is 10−4 g·m−2·d−1, 10−7 g·m−2·d−1, and 10−7 g·m−2·d−1 order of magnitude, respectively.

The effect of constituent phases on microstructure and high temperature deformation mechanisms of IrRhRuWMo complex concentrated alloys

The alloys with different primary phases (BCC, BCC + HCP, HCP, FCC) were fabricated using the same alloying elements: Ir, Rh, Ru, W, and Mo. Comprehensive microstructure characterization and phase identification were performed to reveal all existing phases present within the selected alloys. In situ strain jump compression test was carried out to assess mechanical properties and explore underlying deformation mechanisms, both at room temperature (RT) and 1500 °C. While a noticeable discrepancy in 0.2 % proof stress was observed among the selected alloys at RT, the difference was significantly minimized at 1500 °C. Furthermore, while the dual-phase structure effectively increased the 0.2 % proof stress at RT, it had a detrimental effect at 1500 °C. All alloys obeyed the power-law relationship both at RT and 1500 °C, exhibiting relatively high stress exponents. Together with calculated activation volume, these findings suggested that different rate-limited deformation mechanisms were likely activated at RT and 1500 °C.

In situ fabrication of oxygen deficient Bi2MoO6/InVO4/CeVO4 dual S-scheme ternary heterostructure for robust photocatalytic H2 and H2O2 production

Mild in situ synthesis of ternary dual S-scheme heterostructure photocatalyst with high redox ability of photo-excitons is a pragmatic approach for achieving rapid activation of tenacious atmospheric molecules. In the present study, a series of Bi2MoO6/InVO4/CeVO4 ternary heterostructures were constructed by in situ deposition of Bi2MoO6 nanoplates over one pot synthesised InVO4/CeVO4 using a facile oil bath heating method. The as-synthesised heterostructure materials were comprehensively characterised to understand their structural, optical, electrochemical and morphological properties. The ternary heterostructure displayed a distinct morphology consisting of Bi2MoO6 nanoplates, CeVO4 nanosheets and InVO4 nanorods. The significant intergrowth among the constituent phases through the in situ coupling strategy also led to the construction of tight interfacial microscopic junctions. The important attributes of the ternary heterostructures included intense photon absorption in whole UV–visible region, drastic decrease in photogenerated charge recombination and higher excited state lifetime. Both InVO4 and CeVO4 individually as well as the ternary heterostructure contained surface oxygen vacancies that further promoted efficient charge separation and activation of atmospheric molecules. The optimised ternary photocatalyst displayed 2314 μmol/g/h H2 generation and 1700 μM/g/h H2O2 production which are 12–86 and 11–27 times higher than the pristine semiconductors, respectively. Detailed band position assessment and radical entrapment analysis suggested the occurrence of a dual S-scheme charge transfer mechanism that rationally accounted for the remarkable enhancement in the photocatalytic performance.

Development and experimental validation of a thermo-metallurgical-mechanical model of the laser metal deposition (LMD) process

The current paper presents the development and experimental validation of a thermo-metallurgical-mechanical model for a multi-pass Laser Metal Deposition (LMD) process, with the objective of accurately predicting the resultant constituent phases and residual stresses. The thermal model is calibrated using temperature readings and is shown to accurately capture the transient temperature field and extent of the fusion zone associated with the multi-pass LMD process. The metallurgical model incorporates the kinetics of ongoing solid-state phase transformations (SSPTs) and tempering reactions. The predictions are validated via hardness measurements, demonstrating a very good agreement with the predictions. The developed mechanical model predicts the residual stress field, which is validated using X-ray diffraction measurements, and the comparison also shows a very good agreement between the predictions and measurements. The validated numerical model is then used to explore alternative LMD strategies showing that the choice of deposition strategy can significantly impact resultant constituent phases and residual stresses.

Electron Microscopic Analysis of the Nb<sub>5</sub>Si<sub>3</sub>/NBC/NbSi<sub>2</sub> Composite Structure

The method of aluminothermic self-propagating high-temperature synthesis was used to obtain a composite material based on Nb-Si-C. The study of this system is of interest from the point of view of obtaining high-temperature materials of a new generation for gas turbine engine building, capable of replacing heat-resistant nickel alloys, as well as the potential possibility of forming MAX-phases (phases Mn + 1AXn where n = 1, 2, 3, ...; M is transitional d-metal, A – p-element, X – carbon). The resulting Nb-Si-C composite were studied by X-ray diffraction, scanning electron microscopy, and X-ray spectral microanalysis. It is shown that NbC carbide and silicides γ-Nb5Si3 and NbSi2 are formed in the sample. A detailed analysis of the morphological distribution of the constituent phases has been carried out.

Supercritical hydrothermal synthesis of ultra-fine Cu powders

ABSTRACT Ultra-fine Cu powders were synthesized using supercritical water as a reaction medium and formic acid as a reducing agent. The effects of reducing agent, reaction temperature, and complexing agent on the phase constituents, particle size distributions and morphology of the synthesized ultra-fine Cu powders were investigated. A complex mixture of Cu2O and Cu powders formed by pure supercritical water while high purity homogeneous ultra-fine Cu powders can be synthesized by supercritical water with formic acid as a reducing agent. Moreover, fine tuning of particle size and morphology can be realized by the addition of Ethylenediamine tetraacetic acid (EDTA). The modification mechanism of EDTA on the surfaces of ultra-fine Cu powders was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. EDTA adsorbed on the surfaces of nanoparticles by the dehydration reaction of carboxyl groups in the molecule of EDTA and hydroxyl groups on surfaces of copper nanoparticles (CuOH).

Characterization of microstructure and oxidation behavior of Al modified MoSi2 coating on Nb-Si based alloy

The aim of this work is to investigate the effects of Al on the microstructure formation and oxidation behavior of MoSi2 coating on Nb-Si based alloy by slurry sintering. The results indicate that the addition of a small amount of Al has little effect on the formation of MoSi2 coating. The phase constituent and structure of the inter-diffusion zone (IDZ) at the interface change significantly with the increase of Al content. The Al2O3 formed during the coating preparation process can hinder the diffusion of Si and Fe, thus suppressing formation of Mo5Si3 and Nb4Fe3Si5 layers in IDZ of the coatings with higher Al, but instead forming Fe-rich (Ti,Nb)5Si4 layer and (Nb,X)5Si3 layer. The higher amount of Al2O3 will increase the sintering resistance between the Mo and Si, resulting in a high porosity of the MoSi2 coating. By comparison, the 0.1Al coating exhibits the best oxidation resistance at 1250 °C. The preferential oxidation of Al promotes the formation of SiO2, which is conducive to the rapid filling of pores in the lower part of MoSi2 coating, forming a dense mixed layer of MoSi2+Mo5Si3+SiO2. However, adding a higher content of Al reduces the oxidation resistance of the coating.

Molecular dynamics simulation of interfacial mechanical properties of crumb rubber concrete

Crumb rubber concrete is a new type of cement concrete made from waste rubber as partial aggregate. The mechanical properties and resistance to cracking of crumb rubber concrete are not only related to the mechanical properties of each constituent phase, but also closely related to the interface characteristics and interactions between the cement paste and rubber/aggregate. This article uses molecular dynamics simulation to analyze the two characteristic interfaces (coarse aggregate/cement paste, rubber/cement paste) in the micro and nano structures of crumb rubber concrete at the molecular scale. By simulating the indentation process, interfacial adhesion energy, and interfacial pull-out performance, the micro mechanical properties and mechanisms of different interfaces were further compared and analyzed. From the simulation results, it can be seen that the C-S-H/calcite interface is mainly composed of ion bonds, with the highest interaction force. The C-S-H/silica interface is mainly composed of hydrogen bonds, while the C-S-H/rubber interface is mainly composed of van der Waals force, with the lowest interaction force. The C-S-H/calcite interface has the highest adhesion energy, while the C-S-H/rubber interface has the lowest adhesion energy. In interface indentation simulation, calcite has the greatest impact on C-S-H, while rubber has the smallest impact on C-S-H.

Effect of Mn content in the Ti/Zr-based AB2 Laves type alloys on their electrochemical performance

In this work, we studied the impact of Manganese content on the structural and electrochemical properties of the AB2 Laves phase alloys. These multicomponent alloys were composed of 7 individual constituents with a composition Ti0.15Zr0.85La0.03V0.12Mn0.7+xFe0.12Ni1.2 and a variable Manganese content, x = 0.021, 0.035, 0.070. The alloys were prepared using arc melting and rapid solidification techniques. These alloys were characterized by X-ray diffraction and Scanning Electron Microscopy with X-ray Energy Dispersive Spectroscopy allowing to probe the phase-structural composition of the alloys, their microstructures, and elemental distribution among the phase constituents. The rapidly solidified alloys exhibited refined microstructures with a more uniform elemental distribution compared to their as-cast counterparts, the latter containing larger grain sizes and clustered La-rich phases. C15 and C14 Laves type structures contributed to the phase-structural composition of the alloys, with their proportions influenced by the Manganese content and the chosen preparation method. The study revealed a multi-feature relationship between the Manganese content, the phase abundances, and the electrochemical performances, with notable disparities between as-cast and rapidly solidified alloys. The alloy containing 3 wt% Manganese demonstrated the highest discharge capacity and superior activation performance for both preparation methods, suggesting the best choice when optimizing the composition of the anodes for achieving the best battery performance. The highest hydrogen diffusion rate was observed for the alloy containing 10 wt% Manganese which can be related to the catalytic role of Manganese in the processes of hydrogen exchange when present in these alloys.

Macro and micro-scale material removal mechanisms during ECM/hybrid laser-ECM of a passivating multiphase NbC–Ni cermet

Electrochemical machining (ECM) is a non-contact and athermal machining process where the material removal is accomplished through controlled anodic dissolution of the workpiece governed by Faraday laws. ECM process has been hybridized with several other processes for improving material processing windows. Hybrid laser electrochemical machining (LECM) synergistically applies electrochemical and laser process energies with added benefits of escalated reaction kinetics leading to enhanced transpassive dissolution, weakening of passivation layer, process localisation and uniform dissolution. The laser energy acts as a localised and controllable heat source thereby offering multi-fold processing benefits. For alloys and cermets, a characteristic surficial fingerprint is the presence of inhomogeneous multiphase dissolution and sporadically distributed passivation layer, necessitating addition of aggressive reagents in electrolytes. LECM has the potential to addresses these challenges while processing in pH neutral electrolytes. Previous works have very limited analysis on the macro and micro removal mechanisms while processing relevant strategic materials and multitude of applications of LECM remain unexploited. Therefore, this work presents in-depth investigations into macro and micro-scale material removal mechanisms of ECM/LECM on sintered niobium carbide with nickel binder (NbC–Ni), which is a potential cobalt-free alternative to tungsten carbide. The results revealed new insights into the removal behaviour of the constituent phases which differed from the first principles and their interaction with the laser. During ECM, the Ni phase dissolved preferentially and influenced the surface pattern and particle breakout which was reduced with laser assistance. The surface evolution characteristics were also analysed based on the ridge-crevice pattern. Additionally, the weakening of passive layer was correlated with the pulse analysis that revealed quantitatively the different process regimes occurring during ECM and LECM. The grain level study revealed that orientation effects still exist during LECM and the grains with higher surface energy (FCC (001) vicinal planes) passivated more and dissolved less. Furthermore, the improvement in surface quality, overcut and reduction in particle breakout with LECM process makes it promising for machining newer recipes of metal carbides.

Liquidus surface projection and isothermal section at 1500 °C of (Mo-5Nb)-Ti-C pseudo-ternary system

The liquidus surface projection and isothermal section at 1500 °C of the (Mo-5Nb)-Ti-C pseudo-ternary system were experimentally determined. X-ray diffraction analysis and scanning electron microscopy in conjunction with electron-probe microanalysis were carried out to analyze the solidification behavior and phase constituents. The replacement of 5 at.% Mo with Nb was found to negligibly affect the solidification path or the formation of new phases. However, the quasi-peritectic point U2 shifted closer to the (Mo-5Nb)-C border in the liquidus surface projection than in the Mo-Ti-C system. The BCC single-phase region, BCC + TiC two-phase region, and BCC + Mo2C + TiC three-phase region were determined in the isothermal section at 1500 °C. The replacement of 5 at.% Mo with Nb was found to expand the BCC + TiC two-phase region and narrow the BCC + Mo2C + TiC three-phase region by stabilizing the TiC phase. Therefore, the addition of Nb to the Mo-Ti-C system expanded the compositional range of the BCC + TiC two-phase region, leading to variable properties of TiC-dispersed BCC-based alloys and BCC-TiC cermets.

Effects of High Al Content on the Phase Constituents and Thermal Properties in NiCoCrAlY Alloys.

MCrAlY (M = Ni and/or Co) metallic coatings are essential for the protection of hot-end components against thermal and corrosion damage. Increasing the Al content is considered a feasible solution to improve the high-temperature performance of MCrAlY coatings. In this paper, the effects of high Al contents (12-20 wt.%) on the phase constituents and cast microstructures in MCrAlY alloys were studied by high-energy X-ray diffraction and electron microscopy techniques combined with phase equilibria calculations. High Al content improved the stability of β, σ, and α phases. Meanwhile, an evolution of the cast microstructure morphology from a dendrite structure to an equiaxed grain structure was observed. The thermal properties were analyzed, which were closely related to the phase constituents and solid-to-solid phase transitions at evaluated temperatures. This work is instructive for developing high-Al-content MCrAlY coatings for next-generation thermal barrier applications.

Fabrication and luminous properties of BaAl2O4-LuAG:Ce composite phosphor ceramics for solid-state laser lighting

Based on the “effective ionic radius match effect” and the “charge balance substitution rule of ions”, mixed Ba2+, Al3+, Lu3+, and Ce3+ ions can be effectively regulated to a BaAl2O4-LuAG:Ce biphasic structure. The contribution of BaAl2O4 like as scattering centers can reduce overall reflection losses and enhance the light extraction efficiency of these composite phosphor ceramics (CPCs). In this work, a series of x wt.% BaAl2O4-LuAG:Ce (x = 0, 3, 5, 10, 15) CPCs were fabricated by vacuum sintering using co-precipitated composite powders. Homogenization at the atomic level of mixed Ba3+, Al3+, Lu3+, and Ce3+ ions in multiphase powders provides uniform distribution of BaAl2O4 and LuAG:Ce constituent phases in composite ceramics. The introduction of BaAl2O4 has an additive effect, which also consists in uniform aggregation of pores near their grains during sintering. It allows to adjust the size and amount of microstructural defects by varying the secondary phase content. Under the excitation of 10.8 W 450 nm LDs in a reflection mode, 3 wt% BaAl2O4-based CPCs show the optimum luminous flux of 2244 lm and a luminous efficiency of 208 lm·W−1. The obtained CPCs show a high application potential in solid-state laser lighting.

Evolution of microstructure, mechanical properties and phase stability of CoCrFeMnNi high entropy alloys

In the present study, the microstructure and mechanical properties of various CoCrFeMnNi high-entropy alloys were investigated. Analytical studies were conducted to determine the optimal chemical composition, mixing entropy, mixing enthalpy, atomic radii, valence electron concentration (VEC), dimensionless parameter, and melting point on the Co-Cr-Fe-Mn-Ni system. The microstructure of the alloys was analyzed using FESEM, XRD, and TEM. The results showed that the microstructure of all HEAs had dendritic and interdendritic regions, with secondary precipitations detected along the grain boundaries of the alloy, mainly composed of Mn and Ni. High-density dislocation structures and nano-precipitates were predominantly present in the alloy. The mechanical characteristics such as microhardness and tensile properties are conducted at room temperature. The HEA Co25Cr25Fe10Mn30Ni10 exhibited the highest average microhardness, while the Co20Cr20Fe30Mn10Ni20 HEA had the lowest mean hardness value. This significant difference of 7.2 % may be attributed to the hard phases composed of Mn and Ni. The results of the tensile experiments indicate that the Co20Cr20Fe20Mn20Ni20 alloy has the most favorable overall properties, with an ultimate tensile strength of 441 MPa. This represents a significant increase of 37.8 % compared to 20Cr20Fe20Mn20Ni20. Furthermore, the study examines the instability of the solid-solution state caused by differences in the valence electron concentrations of the constituent elements and phase stability.

Silver-promoted ceramic conversion treatment of Ti6Al4V alloy and its mechanical performance

In this paper, the Ti6Al4V alloy surface was modified via ceramic conversion treatment (CCT) with or without a pre-deposited silver layer. After characterizing the surface morphologies, microstructure and phase constituents of the ceramic oxide layer formed at 620 °C, we investigated the surface hardness and the cross-sectional nano-hardness profile under the oxide layer. The static load-bearing capacity of the oxide layers was examined by applying discrete loads via a Vickers indenter and observing the indentations. A scratch test was used to evaluate the load-bearing capacity and the adhesion/cohesion of the oxide layers. The wettability of the surface changed due to the incorporation of silver and the change of surface morphology. Reciprocating friction and wear test was used to assess the tribological properties. Small and dispersed silver nanoparticles and clusters were found in the oxide layer of the Ag pre-deposited Ti6Al4V samples, and they had much better tribological properties in terms of reduced coefficient of friction and wear volume. With the assistance of silver, the efficiency of the CCT was significantly improved.

Formation mechanism of large-sized CaO-SiO2-CaF2-Al2O3-MgO composite inclusions in super 304H stainless steel rods

Employing silicon deoxidation in the production of Super 304H stainless steel, large-sized CaO-SiO2-CaF2-Al2O3-MgO (CSFAM) composite inclusions are frequently observed in the rods, posing a substantial threat to product quality. This study delves into an analysis of the constituent phases of these large-sized inclusions, identifying the coexistence of liquid phase and spinel phase. Leveraging industrial experiments, systematic sampling of Super 304H stainless steel, and a comprehensive analysis involving dynamic and thermodynamic calculations, this study investigates the formation mechanism underlying such inclusions. The composition of inclusions in the sample before AOD tapping mirrors that of the slag, with high CaF2 content, indicating that they come from slag entrapment. Through kinetic calculations, it is indicated that the time of existence of the liquid film during the ascent of these inclusions is significantly longer than the collision time. This suggests that they are not easily removed and tend to persist in the steel. Despite LF refining, the predominant types of inclusions remain unchanged, and the decrease in temperature leads to the precipitation of solid-phase MgO within the inclusions. Solubility calculations for solid-phase MgO show a rising trend with temperature. Post-casting, MgO and Al2O3 content in inclusions increase, the solid-phase MgO region disappears, and in the subsequent cooling process, inclusions precipitate the stable spinel phase (MgAl2O4). Solubility calculations for solid-phase MgAl2O4 show a temperature-dependent increase. After the completion of casting, the steel ingot undergoes a deformation process through rolling, leading to the transformation of inclusions into large-sized, elongated, composite CSFAM inclusions.

Effects of Zr and Hf on superelasticity, shape memory effect and microstructure of β-type (Ti–Zr–Hf)–Nb–Sn multi-principal element alloys with low magnetic susceptibility

(Ti–Zr–Hf)(97−x)–xNb–3Sn (Ti:(Zr + Hf) = 1:1) alloys were designed for biomedical superelastic alloys with magnetic resonance imaging (MRI) compatibility. The effects of Zr and Hf on constituent phases, superelasticity, shape memory effect and magnetic susceptibility were clarified. The specific Nb content for superelasticity and shape memory effect was also explored. It was found that the (Ti–Zr)–6.5Nb–3Sn alloy exhibited a superelastic recovery strain of 5.2 % with lower magnetic susceptibility compared to conventional Ti–Ni and Ti–Nb alloys. The magnetic susceptibility decreased with increasing Hf content. The (Ti–Hf)–9Nb–3Sn alloy showed a superelastic recovery strain of 0.9 % and very low magnetic susceptibility less than half of that of the conventional alloys. Based on the lattice parameters of these alloys, it was found that these alloys exhibited larger transformation lattice strain between a β phase and an α” phase than those of the Ti–Nb alloys, suggesting high potential to exhibit a large superelastic recovery strain. According to orientation analyses of constituting grains, the larger superelastic recovery strain in the (Ti–Zr)–6.5Nb–3Sn alloy than that of the (Ti–Hf)–9Nb–3Sn alloy is considered to be caused by a strong recrystallization texture of {001}β <110>β. By optimization of heat-treatment temperature, superelastic recovery strain of 3.6 % was achieved in the (Ti–0.5Zr–0.5Hf)–7.5Nb–3Sn alloy.

Oxidation behaviour of Al2O3-forming Cr-based alloys at elevated temperatures

This work presents oxidation behaviours of Al-bearing Cr-based alloys GA1 (51Cr-22Al-13Mo-9Ta-5Si in at%) and GA2 (40Cr-33Al-13Mo-9Ta-5Si in at%) at 1100–1400 ˚C for up to 24 h. The formation of oxides on the surfaces was influenced by constituent phases; BCC phase was rich in Al and formed only α-Al2O3, complex oxides (Cr2O3, AlTaO4, CrTaO4, and Ta2O5) occurred on top of C14 Laves phase. Sufficient Al content is crucial to the formation of protective α-Al2O3, as GA2 was able to resist severe oxidation at 1400 ˚C with an oxidation weight gain of only 3.3 mg/cm2 after 24 h.

Elucidating different selective corrosion behavior of two typical marine aluminum bronze alloys from the perspective of constituent phases

The selective corrosion behavior of two typical marine aluminum bronze alloys (i.e., NAB and MAB) were investigated comparatively. The characteristics of each constituent phase in NAB and MAB including composition, morphology, distribution and work function were analyzed, and their roles in the micro-corrosion behavior were elucidated. MAB exhibits de-alloying corrosion, whereas NAB shows localized selective phase corrosion. The crucial factor causing different selective corrosion behavior is the morphology and distribution of constituent phases. The results reveal correlations between selective corrosion behavior and microstructure and provide insights into improving corrosion resistance of aluminum bronze alloys on the concept of microstructure tailoring.

Effect of thermomechanical processing on mechanical properties and microstructural evolution of Al-Mg-Zn alloy

This study investigates the impact of thermomechanical processing route on the microstructural evolution, and mechanical properties (tensile strength, hardness and elastic plastic (J1c) fracture toughness) of the 7075-aluminum alloy. As received 7075 Al Alloy underwent for the solution heat treatment (SHT) followed by artificial aging and cold rolling (CR) process, respectively. Generally, it was observed that cold rolling of 7075 Al alloy is very challenging, but in this work 90 % cold rolling successfully achieved by optimizing the thermo-mechanical process. The novel heat treatment process for achieving the 90 % cold rolling reduction as follow: firstly, SHT was performed at 470°C for 8 hours(h), there after aging at 140°C for 21 h was performed. Characterization techniques like X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) was employed to assess the microstructure and phase constituents. Elastic plastic (J1c) fracture toughness was studied well on SHT, peak aged and rolled sample. Additionally, Vickers hardness and tensile test were performed. Aging and Cold rolling treatment effectively enhanced tensile strength and hardness ascribed to formation of fine rod shape precipitates of η"(Mg2Zn3) and formation of sub grains with localized strain accumulation, respectively. Split diffraction spots with satellite pattern in long range ordering has also observed in selected area electron diffraction (SAED) pattern of η" attributable to stacking faults and periodic arrangement of precipitates, respectively, as a consequence of this 90 % cold rolling of 7075 Al alloy was accomplished. The maximum Vickers hardness, Tensile strength and Elastic plastic (J1c) fracture toughness values were achieved after SHT (470°C for 2 h), peak aged (PA) (140°C for 21 h) and 90 % cold rolling are 226 HV, 526 MPa and 344.54 kJ/m2, respectively.