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A multiple processing technique that combines cold spraying (CS) and accumulative roll bonding (ARB) was designed to prepare multilayered 1060Al/Al–Al2O3 composites with improved ductility. Microstructural evolution during processing was characterized using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The deposited Al–Al2O3 complex layer was well bonded to the 1060Al matrix, and during ARB processing, the deposited layers were highly squeezed to eliminate voids, Al2O3 particles were split to reduced size and dispersed to a homogeneous distribution within the deposited layers. The tensile test results revealed that the best combination of strength and ductility was achieved in the sample with optimized 3-pass ARB processing, with an increase of ∼41.66% in ultimate tensile strength (153 MPa) and an increase of ∼95.73% in tensile elongation (7.34%) compared to the initial As-Annealed sample. Fracture behavior of the prepared composite was also analyzed. The analysis of microstructural features provided insight into the underlying mechanisms explaining the high strength and great ductility.

Part 1 : https://bura.brunel.ac.uk/handle/2438/26029 The present paper is the second part of a previously published overview entitled “ten years of severe plastic deformation (SPD) in Iran”. Part I concentrates on the equal channel angular pressing (ECAP). In this part, the focus is on the accumulative roll bonding (ARB) because, currently, Iran is ranked the first in the world by the total number of publications in this field. In the present section, the emphasis is not on the microstructure and ultrafine-grained materials produced by ARB. Instead, its focus is on several aspects of ARB to which small attention has been paid so far. The impact and contribution of Iran to each category is evaluated in comparison to researchers from other countries. The main interest of Iranian researchers in the field of ARB is to fabricate the composite materials, particularly metal matrix composites (MMCs). The Iranian researchers were the first who introduced ARB as an effective method to produce particulate MMCs. Shahid Chamran University of Ahvaz and Shiraz University

Influence of accumulative roll bonding (ARB) and conventional cold rolling (CR) on the mechanical and corrosion properties of an AA5083 type alloy with 4.2 wt% Mg and a modified alloy with 5.1 wt% Mg and addition of 0.5 wt% Zn was studied. Tensile tests showed significant increase in strength and a decrease in elongation after each ARB deformation and cold rolling reductions. The advantage of ARB processing over conventional cold rolling was due to the possibility to achieve high degree of deformation and a grain structure refinement. Higher Mg content in a modified AA5083 alloy contributed significantly to the increase in strength, while strain hardening potential and corrosion resistance were reduced. The higher strength level of cold rolled material was attributed to higher dislocation density and the hardening effect due to more intensive dislocation interactions compared to ARB processed material. Results of nitric acid mass loss test (NAMLT) revealed that cold rolled (CR) monometal and ARB processed multilayered specimens were resistant toward intergranular corrosion (IGC) in as-deformed state. However, after 7 days of sensitization at 100 and 150 °C, CR material of AA5083 alloy became IGC sensitive, while ARB specimens stayed resistant. On the other hand, both cold rolled and ARB processed specimens of a modified alloy became IGC susceptible after sensitization. IGC susceptibility of the tested alloys can be correlated with different morphology and distribution of β-phase (Mg2Al3) precipitated during sensitization. It was found that an extensive shear banding within ARB multilayered structure and the existence of passive film between the layers contributed a favorable distribution of β-phase in the structure of IGC resistant ARB specimens. In case of IGC susceptible cold rolled specimens, large amount of β-phase precipitated preferentially along the elongated grain boundaries. Electrochemical parameters were in a good correlation with the results of NAML tests, which in turn, confirmed the superiority of ARB multilayered structure over conventional cold rolled structure in terms of IGC susceptibility and corrosion stability. Ispitivan je uticaj akumulativnog spajanja valjanjem (ARB postupak) i konvencionalnog hladnog valjanja (CR postupak) na mehanička i koroziona svojstva standardne AA5083 legure sa 4.2 mas. % Mg i modifikovane legure, sa sadržajem Mg od 5.1 mas.% i dodatkom 0.5 mas.% Zn. Rezultati ispitivanja jednoosnim zatezanjem pokazali su da dolazi do značajnog povećanja parametara čvrstoće i smanjenja izduženja nakon svakog ARB provlaka i sa porastom stepena deformacije CR postupkom. Pokazana je prednost ARB postupka nad klasičnim postupkom hladnog valjanja obzirom da se mogu postići veći stepeni deformacije i veća rafinacija strukture. Pokazano je da povišen sadržaj Mg doprinosi porastu čvrstoće, dok se potencijal za ojačavanje i koroziona otpornost smanjuju. Viši nivo čvrstoće CR traka rezultat je veće gustine dislokacija i izraženijeg deformacionog ojačavanja zbog intenzivnije interakcije dislokacija kod konvencionalnog valjanja u odnosu na ARB postupak. Rezultati testa gubitka mase (NAMLT) pokazali su otpornost jednoslojnih CR i višeslojnih ARB traka ispitivanih legura prema intergranularnoj koroziji (IGC) u deformisanom stanju. Međutim, nakon 7 dana senzitizacije na 100 i 150 °C, CR uzorci AA5083 legure postaju osetljivi, dok ARB uzorci ostaju otporni prema IGC. Za razliku od standardne legure, CR i ARB trake modifikovane legure pokazale su veliku osetljivost prema IGC nakon tretmana senzitizacije. Osetljivost prema IGC u korelaciji je sa različitom morfologijom i raspodelom β-faze (Mg2Al3) istaložene tokom senzitizacije. Otkriveno je da postojanje smicajnih traka usled intenzivne plastične deformacije u višeslojnoj ARB strukturi, i pasivnog filma između slojeva doprinosi povoljnoj raspodeli β-faze u strukturi otpornih ARB uzoraka što su potvrdili i rezultati elektrohemijskih ispitivanja. U slučaju IGC osetljivih CR uzoraka, velika količina β-faze istaložena je duž granica zrna. Elektrohemijski parametri su u dobroj korelaciji sa rezultatima NAML testa, koji su potvrdili prednost ARB višeslojne strukture u odnosu na konvencionalno hladno valjanu, i ustanovljeno je da ARB postupak ima realnu mogućnost praktične industrijske primene za izradu višeslojnih traka jer omogućava transformaciju Al-Mg legura u materijale novih, pobolјšanih svojstava.

Microstructural changes, such as the density of grain boundary (GB) and dislocation density, due to isochronal annealing in severely plastic-deformed commercial purity aluminium up to 523 K was evaluated using electrical resistivity measurements and scanning transmission electron microscopy. Eventually, the GB density decreases from about 7.2 × 106 to about 2 × 106 m−1, whilst the dislocation density decreases from an initial value of around 1.3 × 1014 m−2 down to around 4 × 1013 m−2.

Al(1060)/Mg(AZ31)/Al(1060) multilayered composite was successfully produced using an accumulative roll bonding (ARB) process for up to four cycles at an elevated temperature (400 °C). The microstructure evolution of the composites and the bonding characteristics at the interfaces between Al and Mg layers with increasing ARB cycles were characterized through optical microscopy, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It was found that the grains of Al and Mg layers were significantly refined and Al3Mg2 and Al12 Mg17 intermetallic compound layers formed at the Al/Mg bonding interfaces. The strength increased gradually and the ultimate tensile strength (UTS) reached a maximum value of about 240 MPa at the third pass. Furthermore, the strengthening mechanism of the composite was analyzed based on the fracture morphologies.