Electron backscatter diffraction (EBSD) was used to evaluate the evolution of microstructure and texture in an Fe-36%Ni (wt. %) alloy after processing by high-pressure torsion (HPT) up to 10 turns at ambient temperature and 250 C. HPT processing led to a strong microstructural refinement with average grain sizes of~0.30 and~0.24 mm at ambient temperature and 250 C, respectively. The high-angle grain boundary fraction was slightly higher after processing at 250 C and gradually increased with increasing numbers of HPT turns to saturate after 5 turns. The crystallographic texture after HPT processing at ambient temperature was characterized by typical A and B fibers of a simple shear FCC texture with domination of the B component. By contrast, the A, B and C components developed during HPT processing at 250 C with C as the dominant texture component. The microhardness values for both HPT deformation conditions were very similar with a continuous increase with increasing HPT turns and almost saturation after 5 HPT turns. The grain size dependence of the microhardness followed the Hall-Petch relationship. The explanation for the microstructure, texture and microhardness difference was attributed to a dynamic recovery process that operates during processing at 250 C.
The microstructure and texture of an Al1050/AZ31/Al1050 laminated composite fabricated by accumulative roll bonding at 400°C up to 5 cycles are investigated using Electron BackScatter Diffraction, neutron diffraction, microhardness measurements and tensile tests. EBSD analysis has shown that ARB processing led to microstructural refinement with equiaxed grain microstructure in AZ31 layers and to the development of elongated grains parallel to the rolling direction in Al 1050 layers. No new phases formed at the bond interface after the first ARB cycle while Mg 17 Al 12 and Mg 2 Al 3 phases appeared after subsequent cycles. During the ARB processing, a typical strong basal (0002) texture is observed in AZ31 layers along with a weak rolling texture showed in Al 1050 layers with a dominant Rotated Cube {001}〈110〉 component. The microhardness of Al1050/AZ31/ Al1050 laminated composite increased with increasing ARB cycles and almost saturated after five ARB cycles. The yield strength and ultimate strength increased gradually between 1 and 3 ARB cycles due to the strain hardening and grain refinement. They decreased with further increasing of the ARB cycles because of crack and failure of the Mg x Al y intermetallic compounds which developed during 4th and 5th ARB cycles. The deformation behavior of the laminated composite becomes rather similar to the behavior of AZ31 alloy that underwent a dynamic recrystallization during processing.
In this study, the microstructure, texture, and mechanical properties evolution of Ni-14W (wt. %) alloy processed up to four cycles of accumulative roll-bonding (ARB) were investigated using electron backscatter diffraction, microhardness measurements, and tensile tests. The initial equiaxed grains, with an average size of 10 μm, underwent a strong refinement after ARB processing. The elongated ultrafine grains were parallel to the rolling direction, with a grain thickness of 0.2 µm. The texture after ARB processing was characterized by the typical rolling components (Copper, S and Brass), which showed a tendency toward stabilization after four cycles. The microhardness increased substantially (+86%) and seemed to saturate after three cycles. The tensile tests demonstrated that Ni-14W samples subjected to ARB processing exhibited high strength (> 1200 MPa after three ARB cycles) and very poor ductility.
The aim of the present study is to investigate the effect of deformation conditions on the corrosion behavior of AZ31 (Mg-3Al-1Zn, % wt.) in 0.9% NaCl (wt.%) solution. The AZ31 alloy was hot rolled at 360 °C to 20 and 50% of thickness reduction. Electrochemical measurements were used to study the corrosion behavior of AZ31 alloy. Analysis of corrosion products after immersion test was performed using optical microscopy, X-ray diffraction and Raman spectroscopy. The mechanical properties of corroded samples were investigated using tensile test at room temperature. Results indicated that the corrosion rate was strongly affected by the hot rolling level. A lower corrosion potential and reduced polarization resistance was observed after hot rolling compared to the as received AZ31 alloy. The corrosion product was evidenced mainly as Mg(OH)2 compound exhibiting a filiform-like morphology. Apparently, the corrosion improved the room temperature ductility of AZ31 alloy.
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