In the present research, the effects of cyclic accumulative roll bonding and intermediate annealing on the microstructural evolution, intermetallic compounds formation and mechanical properties of lightweight Cu-Al multi layered composites were investigated. Commercially pure copper and aluminum 1050 sheets were used to prepare initial sandwich which was then underwent as many as five ARB cycles, with an intermediate annealing treatment at 450 degrees C for 1 h. Comprehensive microstructural analysis using optical microscopy, scanning electron microscopy, and X-ray diffraction were done. Results show that during intermediate annealing significant grain refinement in Cu and Al layers were occurred and the gradual development of intermetallic compounds, particularly Al 2 Cu, AlCu, and Al 4 Cu 9 , at the Cu/Al interfaces were formed. During the intermediate annealing, after each ARB pass, intermetallic compounds form continuous bands between the copper and aluminum layers, and then during each subsequent ARB pass after intermediate annealing, those banded compounds break and distributed in the matrix. In this manner, a homogeneous Cu/Intermetallic/Al composite is obtained. Also, it is seen that with increasing of ARB passes and intermediate annealing times, the volume fraction of brittle intermetallic compounds increased and their morphology changed from continuous layered to homogeneous fragmented and distributed form. The mechanical properties of the processed Cu/Intermetallic/Al composite are largely dependent on the morphology and volume fraction of the intermetallic compounds. When the intermetallic compounds are present in a fragmented form at the interface between the layers or distributed in copper matrix (as occurred after 4 ARB passes), the ductility is greatly reduced due to the increase in stress concentration regions around the intermetallic particles. (c) 2025 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ncnd/4.0/).

Among metallic layered composites, multilayer Al-Ni composites are of scientific and practical interest for special applications such as aerospace and automotive industries. In the present study, multilayer Al-Ni composites were processed using the accumulative roll bonding process and then annealed at different temperatures from 400 to 600 °C for 30-90 min. The effects of accumulative roll bonding and annealing on the quality of the layered composite, the microstructural changes and the properties of the interfaces between the layers were investigated. The microstructural investigations were carried out using optical microscopy, scanning electron microscopy, x-ray diffraction and EDS analysis, and the mechanical properties of the processed samples were evaluated by tensile tests and microhardness measurements. The results showed that a continuous layer of intermetallic compounds such as Al3Ni, Al3Ni2, AlNi and AlNi3 was formed at the interface between the layers after annealing and that the dominant mechanism in the formation of the intermetallic compounds is diffuse. The results of the tensile tests also showed that annealing reduced the strength and increased the percentage of elongation of the samples. In addition, the hardness also increased with increasing temperature and annealing time, which is attributed to the increase in atomic diffusion during the final annealing phase.

In low-carbon vanadium microalloyed steels, the complex microalloying elements can alter the behavior and kinetics of the vanadium precipitation. In the present study, the effect of Mo and Nb addition on the precipitation behavior and kinetics of nanometer-sized VC and VCN precipitates were investigated during isothermal treatment. In this respect, isothermal heat treatments at different temperatures (600–750 °C) and holding times (20–3600 s) executed for V–Nb–Mo, V–Nb, V–Mo, and V steels. The kinetics and isothermal precipitation behavior of VC and VCN were examined by using transmission electron microscopy and tensile deformation. Results showed that most of the vanadium precipitates are interphase and random carbides developed in the ferrite matrix. As the isothermal holding time increases, precipitation takes place in five distinct phases: (i) nucleation period, (ii) the early stage of precipitation, (iii) active growth period, (iv) nearly steady state, and the (v) coarsening period. The Mo and Nb enhance the nucleation sites for V precipitation and also slow down the migrating interphase boundaries. The maximum precipitation strengthening was observed in V–Nb–Mo steel that mainly attributed to the existence of higher amount of nanometer-sized interphase precipitates. The synergistic effects of Mo and Nb govern the nucleation and development of VC precipitates, leading to a fine and even distribution of nanoscale precipitates.

Multilayered aluminum composites have attracted increasing attention due to their potential to combine desirable properties of different alloys, making them suitable for lightweight and high-performance structural applications. The accumulative roll bonding (ARB) process is an effective technique for producing such composites with ultrafine microstructures. In the present investigation, dissimilar laminated composite of the AA1050 and AA6061 aluminum alloys was fabricated up to four cycles of the accumulative roll bonding process with intermediate annealing at 350 °C for 10 min. The effect of final annealing at temperatures of 200, 300, 400 and 500 °C for 15, 30 and 60 min on the microstructure and mechanical properties of the developed laminated composites were analyzed using optical microscopy and tensile testing. Results showed that with annealing at 200 °C, the hardness increases compared to the non-annealed sample, which could be due to the hardening by annealing phenomenon, which usually occurs in nanostructured materials, but at annealing temperatures of 300, 400 and 500 °C, the hardness decreases due to the occurrence of static recovery and recrystallization. It is also observed that the recovery and recrystallization delayed at AA6061 layers compared with AA1050 layers. Laminated composites developed through 3 and 4 cycles of ARB show higher tensile strength, due to lower grain size, and higher elongation, due to the low dislocation density, compared with the individual AA1050 and AA6061 sheets. These findings demonstrate that proper control of ARB cycles and annealing parameters can effectively tailor the microstructure and mechanical behavior of aluminum laminated composites.

In the present research, bi-metal Ti-6Al-4 V/Al composites with and without SiC and Al2O3 reinforced were fabricated by cold rolling and post-deformation annealing. The effects of processing parameters on the evolution of interfacial microstructure and growth kinetics were investigated using SEM, XRD, EDS, and micro-hardness tests. The results demonstrated that TiAl3 and Ti(Al,Si)3 were created between the Ti-6Al-4 V and Al layers in the unreinforced and reinforced composites, respectively. The presence of Si in the TiAl3 intermetallic inhibited the growth rate of the TiAl3 layer. This result is confirmed by the kinetic expansion decreasing from n = 1.82 to n = 1.41 in the chemical reaction-controlled stage and from n = 0.41 to n = 0.39 in the diffusion-controlled stage for the reinforced and unreinforced samples, respectively. These values indicate a slower growth rate of the intermetallic layer. Moreover, the transition region occurred earlier in the reinforced samples than in the unreinforced samples. This phenomenon is attributed to the hindered atomic diffusion caused by the presence of Si. Micro-hardness results show that the Ti(Al,Si)3 hardness is HV420 and the TiAl3 is HV398, so the reinforced sample has higher hardness at the interface than the unreinforced samples due to the dissolution of the Si element into the intermetallic.

An ultrafine-grained (UFG) microstructure with a mean grain size of 197 nm was produced in commercially pure titanium by equal-channel angular pressing (ECAP) to explore the effect of annealing treatment (temperature: 100–600 °C, holding time: 60 min) on the mechanical properties of severely deformed Ti. The evolution of microstructure after annealing treatments was studied in different length scales using light and transmission electron microscope, and mechanical properties were evaluated by room temperature tensile tests and microhardness measurements. The results show that UFG Ti exhibits high thermal stability up to 300 °C and thereafter recrystallization and grain growth phenomena occur with increasing annealing temperature. The microhardness of ECAP-ed material shows a sudden drop after annealing at 400 °C corresponding to the occurrence of significant grain growth in the microstructure (from 197 to 1.12 μm), whereas it decreases slightly after annealing temperatures of 100 and 200 °C. A different behavior was observed at 300 °C. Annealing at 300 °C not only preserves the high strength (YS = 735 MPa) of as-ECAP state, but at the same time, it leads to an improvement in tensile ductility (from 16 to 19

Cu-Nb composites, among the realm of metallic composites, have gained significant attention across diverse applications. Intermediate annealing in Cu-Nb composites has not been studied systematically for its effects on different properties. In this research, the effects of accumulative roll bonding (ARB) and intermediate annealing on texture evolution and mechanical properties of Cu-Nb composites were investigated. Two groups of Cu-Nb composites were subjected to ARB up to four passes. Intermediate annealing at 500 °C for 5 min was applied to the specimens in the first group after each rolling pass, while their counterparts in the second group did not undergo any annealing. After the ARB processing, the mechanical properties in the processed composites were evaluated using tensile and microhardness tests. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) analyses were performed on the specimens to investigate the macrotexture and microtexture evolution. Studying the microstructure revealed that increasing the ARB passes decreased the thickness of Cu and Nb layers significantly. The work hardening of Cu and Nb layers with ARB passes led to an increase in the tensile and yield strength of the prepared composites. Texture analysis showed that increasing the ARB passes caused texture weakening with homogeneous texture evolution in the Cu-Nb composite. EBSD evaluation indicated that by increasing the ARB passes, the necklace structure was diminished, which resulted in improving the microhardness and tensile properties of the composite.

Considering the significance of understanding the mechanism of intermetallic compounds formation in Al/Cu composites, in this research, Al/Cu layered composites were processed by hot pressing, cold rolling and then were annealed at temperatures of 300-500 °C for 30-360 min. The Al/Cu interface characteristics, microstructural evaluation, deposits growth behavior and mechanical properties of Al/Cu composites after pressing, rolling and heat treatment have been determined using OM, SEM, EDS, XRD and UTM. The results show that after annealing, intermetallic particles formed during hot press are not growing anymore, but new intermetallic layer begins to nucleate and grow at Al/Cu bonded area and form a new intermetallic layer, and the growth components are 0.56, 0.49 and 0.46 at 300, 400 and 500 °C, respectively. The growth components are good approximations that indicate that the growth of the intermetallic layer is controlled by volume diffusion. Also, the stress–strain curve consists of five distinctive areas due to the nature of deformation of two metals.

In this study, unreinforced Ti-6Al-4V/Al, enhanced composites, with SiC and Al2O3 particles, and hybrid composites containing both particles were successfully fabricated by cold rolling. The fabricated composites were subjected to annealing, and the influence of SiC and Al2O3 particles on the microstructure, chemical composition and growth kinetics were investigated using SEM, XRD, EDS and micro-hardness tests. The results show that the addition of silicon carbide and alumina particles reduced the growth kinetics of the intermetallic layer from 12µm to 4µm at 600˚C and 240 min annealed, and the XRD results proved the formation of the hard Ti(Al, Si)3 phase. The change in intermetallic layer thickness for samples containing reinforcement particles was independent of the type and amount of reinforcement. Moreover, kinetic investigations show the decrease in kinetic expansion at 600 °C from n=1.82 to n=1.41 in the chemical reaction-controlled stage and from n=0.41 to n=0.39 in the diffusion-controlled stage for enhanced and non-enhanced sample respectively indicate a slower intermetallic layer growth rate. Also, the transition region of the enhanced samples occurred earlier than the non-enhanced samples. This is related to the difficulty of atomic diffusion due to the presence of silicon. Micro-hardness results showed that the Ti(Al,Si)3 hardness is HV420 and the TiAl3 is HV398, so due to the dissolution of the silicon element into the intermetallic the reinforced sample has higher hardness at the interface than the unreinforced samples.

The tri-metal Ti-Al-Nb composites were processed through three procedures: hot pressing, rolling, and hot pressing, followed by subsequent rolling. The fabricated composites were then subjected to annealing at 600, 625, and 650°C temperatures at different times. Microstructure observation at the interfaces reveals that the increase in plastic deformation strain significantly affects TiAl3 intermetallic layers’ evolution and accelerates the layers’ growth. On the contrary, the amount of applied strain does not significantly affect the evolution of the NbAl3 intermetallic layer thickness. It was also found that Al and Ti atoms’ diffusion has occurred throughout the TiAl3 layer, but only Al atoms diffuse through the NbAl3 layer. The slow growth rate of the NbAl3 intermetallic layer is due to the lack of diffusion of Nb atoms and the high activation energy of Al atoms’ reaction with Nb atoms.

In this study, the corrosion behavior of stir cast Al/B4C and TiB2 composites was investigated. Reinforcements were added to Al6061 in amounts of 3, 6, and 9 wt.% during stir casting, after which they were undergone five cycles of accumulative roll bonding (ARB) process. The results of electrochemical tests indicated that in the case of as-cast samples, composites with 9 wt.% TiB2 and 6 wt.% B4C displayed the highest corrosion resistance, among which the TiB2 containing sample had the best corrosion behavior. This difference was attributed to the different nature of the reinforcing particles and their distribution. Moreover, it was considered that the ARB process had a positive impact on the corrosion resistance of the samples by causing a uniform distribution of the reinforcing particles in the samples without changing the pitting corrosion mechanism. It was observed that after ARB process, the composite with 6 wt.% B4C had the best corrosion resistance, compared to the sample with 9 wt.% TiB2, because it had less structural defects and homogeneously distributed particles.

In the present research, aluminum metal matrix composites were processed by the stir casting technique. The effects of TiB2 reinforcement particles, severe plastic deformation through accumulative roll bonding (ARB), and aging treatment on the microstructural characteristics and mechanical properties were also evaluated. Uniaxial tensile tests and microhardness measurements were conducted, and the microstructural characteristics were investigated. Notably, the important problems associated with cast samples, including nonuniformity of the reinforcement particles and high porosity content, were solved through the ARB process. At the initial stage, particle-free zones, as well as particle clusters, were observed on the microstructure of the composite. However, after the ARB process, fracturing phenomena occurred in brittle ceramic particles, followed by breaking down of the fragments into fine particles as the number of rolling cycles increased. Subsequently, composites with a uniform distribution of particles were produced. Moreover, the tensile strength and microhardness of the ARB-processed composites increased with the increase in the reinforcement mass fraction. However, their ductility exhibited a different trend. With post-deformation aging treatment (T6), the mechanical properties of composites were improved because of the formation of fine Mg2Si precipitates.

Hot compression tests were performed on AISI 321 austenitic stainless steel in the deformation temperature range of 800–1200°C and constant strain rates of 0.001, 0.01, 0.1, and 1 s−1. Hot flow curves were used to determine the strain hardening exponent and the strain rate sensitivity exponent, and to construct the processing maps. Variations of the strain hardening exponent with strain were used to predict the microstructural evolutions during the hot deformation. Four variations were distinguished reflecting the different microstructural changes. Based on the analysis of the strain hardening exponent versus strain curves, the microstructural evolutions were dynamic recovery, single and multiple peak dynamic recrystallization, and interactions between dynamic recrystallization and precipitation. The strain rate sensitivity variations at an applied strain of 0.8 and strain rate of 0.1 s−1 were compared with the microstructural evolutions. The results demonstrate the existence of a reliable correlation between the strain rate sensitivity values and evolved microstructures. Additionally, the power dissipation map at the applied strain of 0.8 was compared with the resultant microstructures at predetermined deformation conditions. The microstructural evolutions strongly correlated to the power dissipation ratio, and dynamic recrystallization occurred completely at lower power dissipation ratios.

This study investigated the effects of adding graphene nanoplates (GNPs) and carbon nanotubes (CNTs) into the Al7075 matrix via the stir casting method on the microstructure and mechanical properties of the fabricated composites. By increasing the volume fraction of reinforcements, the fraction of porosity increased. The X-ray diffraction results showed that the addition of reinforcements into the Al7075 changed the dominant crystal orientation from (002) to (111). Field emission scanning electron microscopy images also showed the distribution of clustered reinforcements in the matrix. Between the two reinforcements, the addition of CNTs generated a lower fraction of porosities. Through the addition of 0.52vol% GNPs into the matrix, the hardness, ultimate tensile strength and uniform elongation increased by 44%, 32%, and 180%, respectively. Meanwhile, the presence of 0.71vol% CNTs in the matrix increased the hardness, tensile strength and uniform elongation by 108%, 129%, and 260%, respectively.

The effects of the post-deformation annealing on the microstructural evolution of hot rolled Al7075 matrix composites reinforced with CNTs and GNPs were investigated. The multi-pass hot rolling was applied on the stir cast samples. Annealing was then applied to the composites at 450 °C for 4 h. Microstructural evolution was examined by SEM, EDS, and EBSD techniques. EBSD data showed that the addition of 0.87 vol.% (GNPs + CNTs) significantly inhibited the occurrence of recrystallization. Also, in the composite with 0.96 vol.% CNTs, recrystallization was partially inhibited. Whereas, in composites with 0.92 vol.% of GNPs, the occurrence of recrystallization through particle stimulated nucleation (PSN) mechanism was significantly accelerated. The volume fraction of recrystallized grains depends significantly on the occurrence of PSN in the presence of reinforcements. The intensity and type of the main components of the texture as well as the FCC fibers depend on the type of reinforcement.

In the original version of the online article Beitallah Eghbali's family name was misspelled. The original article has been corrected.

In the present research, Al7075 matrix composites containing carbon nano-tubes (CNTs) and graphene nano-plates (GNPs) processed through accumulative roll bonding (ARB). Accumulative roll bonding carried out up to 3 passes at 400 degrees C with 50% thickness reduction per pass. The effect of CNTs and GNPs on the microstructural evolution and strengthening mechanisms were investigated. Microstructural evolutions in processed composites were characterized by using field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). The grain orientation spread (GOS) analysis shows that the volume fraction of recrystallization in deformed grains depends on the level of particle stimulated nucleation (PSN) in the interface between matrix and reinforcement. The occurrence of PSN is affected by the type of reinforcement and the number of ARB passes. The level of PSN depends directly on the extent of the plastic deformation zone (PDZ) in the vicinity of the matrix/reinforcements. In the hybrid composite, the PSN mechanism was restrained due to Zener pinning of grain boundaries. Texture evolution is mainly carried out through beta fiber for the composites subjected to the ARB process. In all ARBed samples, the main texture components include one or two of S, Brass, and Copper. The presence of CNTs and GNPs in the composite led to a change in both intensity and type of the main texture components formed during the ARB. In the composite containing GNPs, with increasing of ARB passes the volume fraction of PSN decreased remarkably due to strain hardening and consequently recrystallization was limited. It was found that the most significant strengthening mechanism which has the key role in the increase yield strength is the load transfer mechanism. The role of coefficient of thermal expansion mismatch and Orowan mechanisms in the increase yield strength and hardness of processed composites is less and the effect of the Hall-Petch mechanism is negligible.

In the present study, AA2024-SiO2np nanocomposites were prepared by the vortex method and effects of SiO2 content on resulting microstructural and mechanical properties were investigated. The results indicate that the addition of 0.5vol% of nanoparticles decreased the size of the dendrite cell intervals by about 16%. The observed mechanical properties exhibited an improvement of about 17, 28, 10, 157, 8 and 13%, in hardness, ultimate tensile strength, yield strength, tensile elongation, flexural and shear strengths, respectively. With more considerable additions of nanoparticles, scanning electron microscopy investigations confirm that there were more significant amounts of nanoparticle agglomerates in the microstructure, which reduced the mechanical properties of 1vol% SiO2np reinforced nanocomposite. The primary strengthening mechanisms evaluated appeared to be the effect of grain refinement (Hall–Petch), Orowan strengthening and the mismatch in coefficient of thermal expansion of the reinforcements and the matrix alloy. Evidence of some agglomerations of nanoparticles was recognized on the tensile fractured surfaces of the nanocomposites.