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AM30 magnesium alloy was subjected to annealing at temperatures ranging from 200 to 450°C for 1–1440 min to evaluate the microstructure and texture evolution during grain growth. The grain growth exponent of n = 9 and activation energy of Q = 105.6 KJ/mol were observed. Precipitates, such as Mg17Al12, Al8Mn5 and Al11Mn4 were observed in the alloy, and they were found to be reduced with increasing the annealing temperature/time. The precipitates further appeared to be dissolved at a higher annealing temperature of 450°C, leading to abnormal grain growth in the alloy. The effects of solute drag and dislocation density on the grain growth behaviour, estimated through a mesoscale model based on cellular automata, were found to be insignificant during annealing. The strong basal texture in the starting material was observed to be weakened up to 480 mins of annealing, and on further increasing the annealing time to 1440 min, the alloy regained its basal texture. It was found that both normal and abnormal grain growth promoted basal texture during the annealing of the alloy. [ABSTRACT FROM AUTHOR]

The effects of microstructure and texture on the mechanical properties of Mg and its alloys have been investigated in the present study. Samples, such as pure Mg, AM30 (Mg–3 wt.% Al−0.3 wt.% Mn), and AME300 (Mg–3 wt.% Al–0.3 wt.% Mn–0.2 wt.% Ce) alloys, were used for the investigation. The samples in the form of hot-rolled plates were subjected to annealing to characterize their microstructures, textures, and mechanical properties. The results revealed that the ductility of pure Mg is dependent on the reduction in basal texture intensity, and its tensile strength is dependent on the average grain sizes of the samples. However, the optimum combination of strength and ductility can be achieved in pure Mg after annealing at 300 °C for 15 min. Similarly, the same can be achieved in AM30 alloys after annealing at 400 °C for 480 min, and in AME300 alloys after annealing at 450 °C for 10 min. However, these Mg alloys after annealing at lower temperatures (i.e., 200 and 300 °C) did not show any correlation between grain size, texture, and mechanical properties of the alloys. This has been attributed to the presence of precipitates in the alloys. It was further found that AME300 alloy had the best combination of tensile strength and ductility compared to AM30 and pure Mg after annealing. [ABSTRACT FROM AUTHOR]

Mg–3Al–0.2Ce alloys were subjected to annealing at temperatures ranging from 200 to 450°C for different periods to evaluate the microstructure and texture developments in the alloy. The grain growth exponent of n = 13 and the activation energy for grain growth, Q = 75 kJmol−1 were observed. A large number of precipitates were observed in the samples. They were found to be Mg17Al12, Al8Mn5, Al11Mn4, Al11Ce3, Al3Ce, Al4Ce, Mg17Ce2, Al10Mn7Ce2, Mg2Ce, Mg3Ce, and Mg12Ce, as confirmed by electron probe microanalysis (EPMA) and X-ray Diffraction (XRD). The precipitates were further found to be dissolved or disappeared with an increase in the temperature of annealing. As a result, the grain boundary mobility was enhanced during annealing at high temperatures and increased the grain growth of the samples. The initial basal texture in the alloy was observed to be tilted (by ∼ 30°) towards the transverse direction of the samples during annealing. Such a texture weakening in the alloy during annealing was attributed to the nucleation and growth of new grains formed in the deformed zone surrounding the precipitates. [ABSTRACT FROM AUTHOR]

Free-end torsion tests were conducted for Ti6Al4V (Ti64) alloy at temperatures of 298 K, 673 K, and 873 K for different strains ranging from 0.22 to 0.99. The microstructure and texture evolution as a function of torsional deformation have been investigated in the present study. A near-equiaxed homogeneous microstructure was observed after deformation at all temperatures. However, the grains were observed to be aligned along the direction of shear stress at larger deformation strains. Dynamically recrystallized (DRX) grains were observed in the samples at higher deformation temperatures, and these were found to be significant at 873 K for strains > 0.66. Dynamic transformation of α → β was also observed during deformation at a temperature of 873 K. The initial fiber texture got rotated toward the ideal B fiber orientation, and reached at the ideal C2 fiber orientation after deformation for a maximum strain of 0.99. The deformation texture was further simulated through the Visco plastic self-consistent (VPSC) method, and it was found that the basal slip was the dominant deformation mode followed by prismatic and both pyramidal I and II slip systems. The flow stress decreased with increase in the temperature of deformation, and a significant flow softening was observed during deformation at 873 K. [ABSTRACT FROM AUTHOR]

In the present study, the microstructure and texture evolution during cold drawing of commercially pure (CP) titanium wires have been investigated. The roles of initial grain sizes, reduction percentages and strain-rates of deformation were also examined. Both tensile and compressive twins were observed in the samples after cold drawing, and the twins were found to be insignificant at higher reduction percentages and at higher strain-rates of deformation. The samples with larger grain sizes had lower volume fraction of twins. Further, the twins were characterized as Schmid and non-Schmid type, and they had similar effect on the microstructural developments in the samples. The textures in the samples after cold drawing were observed to have dominant basal and prismatic orientations. However, the intensity of these texture components got increased for samples with larger grain sizes. Further, the effect of initial grain sizes and strain-rates of deformation were found to be insignificant on the texture evolution during cold drawing. [ABSTRACT FROM AUTHOR]

The role of shear strain and deformation temperature on the microstructure and texture evolution in commercially pure (CP) titanium was investigated in the present study. CP titanium samples were subjected to free-end torsion at elevated temperatures, starting from room temperature (298 K) to 873 K, for different shear strains of 0.5–2.5. Deformation twins of {10 1 ¯ 2} type were observed in the samples deformed at lower temperatures (up to 673 K). Deformation bands were seen in some of the grains and the number of such grains was observed to be decreased with increasing the deformation temperature. Such deformation bands were observed to be facilitated prismatic slip at room temperature and basal slip at high temperatures. However, the presence of deformation twinning always favoured basal slip activity in twinned grains. Dynamically recrystallized grains were observed in the samples deformed at higher temperatures. The texture evolution in the samples was observed to be controlled mainly by activities of basal, prismatic and pyramidal slips. Further, the ideal C1 and C2 fibres were found to be unstable during torsion of the samples and the ideal B fibres were observed in the samples deformed at a temperature of 873 K for a shear strain of 2.5. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V (Ti64) plates were subjected to rolling at 600°C and 800°C, respectively, for reductions up to 90% reduction in thickness. The mechanism of texture and microstructure evolution during rolling was studied in the present study. Extension twins of coherent nature were observed in the samples rolled up to 50% of reduction. The deformation was relatively inhomogeneous in the samples rolled at 600°C compared to that at 800°C. Visco-plastic self-consistent (VPSC) simulation showed that relative activity of pyramidal slip was higher during rolling at 800°C compared to that at 600°C. The average activity of slip systems per grain was less than five for the samples rolled at 600°C and this might be responsible for the strain heterogeneity in the large grains. Further, twinning activity was found to be limited to a true strain of 0.5, as supported by the microstructural observation. VPSC simulation also showed the presence of contraction twins in the samples which was further supported by X-ray texture measurement. Dominant basal texture was observed in the samples irrespective of the temperature of rolling. [ABSTRACT FROM AUTHOR]

In the present investigation, an effort has been made to understand the effect of aluminum addition to α Mg-Li alloys. The corresponding composition Mg-4Li-xAl (x = 0, 2, 4 and 6 wt.%) alloys have been prepared by stir casting route under an argon environment. Extrusion was carried out at 300 °C with the extrusion ratio of 15:1. Significant grain refinement was observed after extrusion. X-ray diffraction-based investigation of the cast and extruded alloys showed the presence of intermetallic compounds such as Mg17Al12 and AlLi in the Al-rich alloys namely, Mg-4Li-xAl (x = 4 and 6 wt.%). These precipitates were also present in the extruded plus annealed samples, indicating the stability of the precipitates at high temperature. The bulk x-ray texture measurement revealed a crystallographic texture where the c-axis of the h.c.p crystals was perpendicular to the extrusion direction (ED) for extruded sample. A texture transition was observed on annealing. The c-axis was oriented parallel to the ED. Mechanical properties of the cast, extruded and extruded plus annealed material illustrate that the addition of Al led to enhancement in hardness, yield strength and ultimate tensile strength. [ABSTRACT FROM AUTHOR]

Commercially pure (CP) titanium plates were subjected to hot rolling down to 50%, 70%, 80% and 90% reduction in thickness through unidirectional rolling (UDR), multistep cross-rolling (MSCR) and reverse-rolling (RR). It was observed that the samples had dominant basal texture (basal fiber) irrespective of the reduction percentages and the modes of rolling. Two types of twins, {1View the MathML source02}<11View the MathML source0 > type tensile twins and {1View the MathML source12}<1View the MathML source00 > type compressive twins, were observed in the microstructures. These twins were present in more abundance in the samples processed under MSCR and RR conditions, particularly for 50% reduction in thickness. A decreasing trend of average grain size, average grain orientation spread and fractions of twin boundaries as well as low angle grain boundaries was observed as a function of deformation for the UDR and RR strain paths. The MSCR samples have shown a deviation from the trend, which has been attributed to dominance of twinning in the deformation mechanism. [ABSTRACT FROM AUTHOR]

The present study elucidates the effects of nanoscale boron nitride particles addition on the microstructural and mechanical characteristics of monolithic magnesium. Novel light-weight Mg nanocomposites containing 0.3, 0.6 and 1.2 vol% nano-size boron nitride particulates were synthesized using the disintegrated melt deposition method followed by hot extrusion. Microstructural characterization of developed Mg/x-boron nitride composites revealed significant grain refinement due to the uniform distribution of nano-boron nitride particulates. Texture analysis of selected Mg-1.2 boron nitride nanocomposite showed an increase in the intensity of fiber texture alongside enhanced localized recrystallization when compared to monolithic Mg. Mechanical properties evaluation under indentation, tension and compression loading indicated superior response of Mg/x-boron nitride composites in comparison to pure Mg. The uniform distribution of nanoscale boron nitride particles and the modified crystallographic texture achieved due to the nano-boron nitride addition attributes to the superior mechanical characteristics of Mg/boron nitride nanocomposites. [ABSTRACT FROM AUTHOR]