Kaushik, Lalit

The current study focuses on investigating the effect of in-plane cyclic shear (IPCS) on the microstructure and texture evolution in an AZX311 Mg alloy sheet using a customized in-plane shear jig. Samples were deformed at two distinct strain levels of 0.05 and 0.10, with tests conducted over different numbers of deformation cycles at each strain level. A detailed microstructural investigation using electron backscatter diffraction (EBSD) revealed that in-plane cyclic shear induced the formation of numerous tensile twins (TTWs) in the alloy sheet. Both the shear strain and the number of deformation cycles contributed to an increase in the twin volume fraction (TVF), which played a critical role in texture evolution. Notably, unlike in-plane shear (IPS) deformation, where two satellite peaks appear in opposite quadrants, in-plane cyclic shear resulted in satellite peaks across all four quadrants of the pole figure. The evolution of texture components across all four quadrants arises from the load variations under forward and reverse loading during cyclic deformation. Thus, in-plane cyclic shear deformation can generate texture components along nearly all directions in the pole figures. Additionally, microstructural and microtextural analyses revealed that TTW is the dominant deformation mechanism, contributing to texture evolution. Furthermore, the resolved shear stress (RSS) analysis indicated that prismatic slip activity predominantly governs dislocation slip behavior. © 2025

In this study, the effects of pre-strain-induced tensile twins (TTWs) and controlled heat treatment on the formability behavior of AZX311 Mg alloy sheets were investigated. A 4% compressive strain was applied to pre-strain the sheets using the in-plane compression (IPC) technique along the rolling direction (RD) to introduce TTWs. The pre-strained (PS) samples were subsequently heat-treated at 250 °C, 350 °C, and 400 °C independently for 1 hr, and are termed as PSA1, PSA2, and PSA3, respectively. Erichsen cupping tests were conducted to assess the formability of the sheet samples under different initial conditions. The results showed that the PS sample heat-treated at 250 °C for 1hr exhibited a decrease in the Erichsen index (IE) compared to the as-rolled sample, whereas PSA2 and PSA3 samples showed an increase in IE values. Microtexture analysis revealed that most of the TTWs generated through pre-twinning were stable at 250 °C; however, the twin volume fraction reduced to 41% at 350 °C compared to the PS samples due to enhanced thermal activity at that temperature. Furthermore, PSA2 samples showed severe grain coarsening in some areas of the sample, and the fraction of such grains increased in the PSA3 samples. The stretch formability (IE value) of PSA2 samples showed a 32.3% increase compared to the as-rolled specimens. Additionally, the analysis of the deformed specimen at failure under the Erichsen test indicated that considerable detwinning occurs in the PS and PSA1 samples, whereas dislocation slip activity dominates in the PSA2 and PSA3 samples during stretch forming. Apart from detwinning and dislocation slip, deformation twins were also observed in all samples after the Erichsen test. Thus, this work highlights the importance of texture control and its underlying mechanisms via pre-twinning followed by heat treatment and their impact on the room temperature (RT) stretch formability of AZX311 Mg alloy sheets.

The stacking fault energy (SFE) of face-centered cubic (FCC) alloys is a critical parameter that controls microstructural and crystallographic texture evolution during deformation and annealing treatments. This review focuses on several FCC alloys, aluminum (Al), copper (Cu), austenitic stainless steels (ASSs), and high entropy alloys (HEAs), all of which exhibit varying SFEs. These alloys are often subjected to thermo-mechanical processing (TMP) to enhance their mechanical properties. TMP leads to the evolution of deformation-induced products, such as shear bands (SBs), strain-induced martensite (SIM), and mechanical/deformation twins (DTs) during plastic deformation, while also influencing crystallographic texture. High-medium SFE materials, such as Al and Cu, typically exhibit the evolution of Copper-type texture during room temperature rolling (RTR), while low SFE materials, such as ASSs and HEAs, display Brass-type texture at high reduction ratios. Moreover, the presence of second-phase particles/precipitates can also impact the microstructure and texture evolution in Al and Cu alloys. Particle-stimulated nucleation (PSN) during the annealing treatment has been reported for Al, Cu, ASSs, and HEAs, which causes texture weakening. Another interesting observation in severely deformed Cu alloys is the room-temperature softening phenomenon, which is discussed in the reviewed work. Additionally, plastic deformation and heat treatment of ASSs result in phase transformation, which was not observed in Al, Cu, or HEAs. Furthermore, the dependence of special boundaries in HEAs on plastic deformation temperature, strain rate, and annealing temperature is also discussed. Thus, this review comprehensively reports on the impact of TMP on microstructural and crystallographic texture evolution during plastic deformation and the annealing treatment of Al, Cu, ASSs, and HEAs FCC materials, using results obtained from electron microscopy.

The current study examined the deformation mechanisms, microstructure, and texture evolution in AZX311 Mg alloy sheets subjected to in-plane shear (IPS) deformation. Different levels of shear strains, with values 0.05, 0.10, and 0.15, were applied along the rolling direction (RD) using a specialized in-plane shear testing jig. The strain measurement for the applied shear deformation was conducted utilizing the digital image correlation (DIC) technique. The strain distribution was found to be nearly homogeneous over sufficiently large areas, thereby allowing the microstructural measurements to yield relevant statistical data. A thorough microstructural examination across the thickness using electron back-scattered diffraction (EBSD) revealed that the application of IPS strain led to the formation of a significant number of tensile twins (TTWs) in the sheet. This was evidenced by the emergence of two satellite peaks at the periphery of the pole figures. As the shear strain increased, the proportion of TTWs in the material also increased, encompassing the entire parent grain and leading to the formation of what has been termed as “all-twinned microstructure”. The microstructural and texture investigation after IPS deformation revealed that TTWs were the dominant deformation mechanism that defined the microstructure and texture under IPS deformation, while dislocation slip activity was dominated by prismatic slip, as evidenced by the resolved shear stress analysis in this study. Consequently, this research highlights the effect of IPS deformation on the microstructure and texture evolution throughout the thickness of an Mg alloy sheet and elucidates the underlying mechanisms.

The evolution of microstructure and texture in Mg-3Al-1Zn-1Ca alloy sheets subjected to in-plane shear (IPS) loading was investigated using experimental techniques and viscoplastic self-consistent (VPSC) modeling. The specimens were deformed under varying degrees of IPS strain (γ₁₂ = 0.05, 0.10, and 0.15) using a customized jig. Electron backscatter diffraction (EBSD) observations revealed profuse tensile twinning (TTW) even at an IPS strain of 0.05, with its intensity continuously increased as the IPS strain increased. The TTWs progressively engulfed parent grains with increasing shear strain, evolving into an unusual deformation twin morphology. Furthermore, VPSC model predictions confirmed basal slip as the dominant deformation mode at low IPS strains, transitioning to prismatic slip dominance at higher IPS strains. The activity of the TTW mode was significantly higher during the initial stages of IPS strain and saturated to lower values at higher strains. VPSC simulation results also indicated preferential shear accumulation on a single twin system, explaining the phenomenon of a single twin variant engulfing a parent grain. Additionally, the influence of individual slip and twin modes on texture evolution was evaluated through orientation tracking of representative grains at various shear strain increments using VPSC simulation. The simulation results quantitatively highlighted the activities of basal slip, prismatic slip, and tensile twinning, establishing a correlation between texture evolution and the underlying deformation mechanisms. © 2025

In this investigation, annealed Cu–0.13Sn alloys i.e., as-received samples were subjected to room-temperature rolling (RTR) at reduction ratios (RR) of 40 and 75 pct. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) was used to discuss the microstructure evolution in the as-received and RTR samples. RTR deformation resulted in the formation of Copper-type shear bands (SBs). An unusual phenomenon of static recrystallization (SRX) at room-temperature (RT)/self-annealing was observed in the severely deformed Cu–0.13Sn alloy. SBs and deformed grain boundaries (GBs) were the main sites with high levels of stored energy (SE), and new grains were nucleated in those regions via discontinuous SRX (DSRX) in the RTR samples. Continuous SRX (CSRX) was observed in grains nucleated inside the deformed grains. The fraction of SBs was increased with increases in the RR, and visco-plastic self-consistent (VPSC) modelling was used to predict the texture of the SBs in the severely deformed Cu–0.13Sn alloy. Microstructural heterogeneities had a significant effect on the evolution of the crystallographic texture in as-received and RTR samples. Under low strain (40 pct RR), a Copper-type texture was observed, whereas the severely deformed sample (75 pct RR) showed strong Copper and S components, but weak Brass component. Self-annealed grains in the SB regions and in the deformed GB regions led to the evolution of strong Copper and Rotated Cube components, but weak Brass component.

In this study, we investigated the influence of cold rolling reduction on microstructural evolution and slip behavior in Ta-10W alloy fabricated by vacuum arc melting (VAM). As the reduction increased, both single and multiple slips were observed within some grain interiors. At reductions of 20% and 40%, deformation bands, primarily consisting of γ-fiber components, formed within the grain interiors. The fraction of deformation bands (DBs) increased with higher reduction. Conversely, at 60% reduction, in addition to DBs, experimentally observed shear bands (SBs) with a herringbone pattern were formed. Both DBs and SBs predominantly formed in regions of concentrated strain (areas with high kernel average misorientation (KAM) and geometrically necessary dislocations (GND)). As the reduction increased, the misorientation angle between the matrix and the DBs or SBs gradually increased, while the width of the DBs decreased. To investigate the violation of Schmid’s law in Ta-10W alloy, slip trace and resolved shear stress (RSS) analyses were performed on observed slip lines within deformed grains. Contrary to conventional slips, where slip typically occurs on the plane with the highest RSS, slips in the Ta-10W alloy were confirmed to occur even on planes with lower RSS in certain grains. Hence, this study provides experimental evidence of Schmid’s law violation in Ta-10W alloy. Copyright

In the present investigation, equiatomic CoCrFeMnNi high entropy alloy (HEA) was subjected to 80% cold rolling (as-rolled) followed by isothermal annealing treatment at 700 °C for different time periods. Microstructural characterization was performed using electron back-scattered diffraction (EBSD) and electron channeling contrast imaging (ECCI) techniques on the as-rolled and annealed samples. The as-rolled microstructure consisted of elongated grains mainly composed of strong α-fiber and weak γ-fiber textures. The as-rolled sample showed the formation of ingrain SBs in the γ-fiber grains, which served as preferential sites for grain nucleation. The annealing treatment of as-rolled samples at 700 °C cause static recovery (SRV) before 5 minutes of heat-treatment, whereas static recrystallization (SRX) was observed after 5 minutes of heat-treatment in the CoCrFeMnNi alloy samples. A faster rate of recrystallization kinetics was observed after 15 minutes of heat-treatment. The annealing treatment reduced the intensity of α-fiber and enhanced the Copper, Cube and P ({011}<122>) texture components. Copper components originated from coarse recrystallized grains, which were the results of localized grain growth phenomena. Unusual behavior of banded featured α-fiber grains was observed during the annealing process. These banded grains in the partially annealed samples consisted of subgrain-boundaries and showed a delayed response to recrystallization as compared to grains with other orientations. Stored energy (SE) and Taylor factor (M) calculations were also used to understand the delayed recrystallization response of the banded featured/retained deformed grains. The microhardness value of the as-rolled sample was approximately 450 Hv, which decreased to around 230 Hv for the fully recrystallized grains.