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AM technologies allow for the fabrication of complicated geometric components at reduced costs and with better functionality. Aside from design complexity, regulating desired textures during AM processes can provide a substantial advantage. Microstructures are typically columnar along the build direction and equiaxed across the build plane. Columnar grain structures are characterized by a high crystallographic texture and mechanical anisotropy. The crystallographic texture is a key material parameter that has a significant impact on a product's functionality. Mechanical anisotropies result from preferred crystallographic orientations. Additive manufacturing processes acquire crystallographic texture primarily through solidification, which is influenced by local heat flow directions and competing grain growth in the chosen crystallographic direction. This paper provides a comprehensive explanation of the foundations of solidification structure and texture as they pertain to additive manufacturing in some of the most widely researched structural metals, particularly steels, nickel-base superalloys, and titanium alloys.

Third generation γ-titanium aluminides with nominal compositions Ti–45Al–5Nb–0.2B–0.2C and Ti–45Al–10Nb–0.2B–0.2C were investigated to identify the phase transformation and their morphological stability with temperature. Electron microscopy and differential scanning calorimetry were employed for the characterization of phases and for recording the corresponding transformations, respectively. It has been inferred that the order–disorder transformation temperatures α2 → α increased with increasing Niobium (Nb), while the α-transus temperature decreases. The stability of the microstructure for both alloys with temperature were also investigated. Mass change measured for the heating rates 20 °C s−1 and 30 °C s−1 reveals that the alloy Ti–45Al–10Nb–0.2–0.2C shows stability up to 1100 °C, and the alloy Ti–45Al–5Nb–0.2B–0.2C is stable up to 900 °C. The orientation relationship between the phases indicates that with the change in shape of the α phase from lamellar to equiaxed, it deviates from the Blackburn orientation relationship.

The evolution of microstructure and texture during selective laser melting (SLM) of silver alloy—sterling silver 925 (AM Ag925) has been investigated and analyzed vis-a-vis cast sterling silver (AC Ag925). The microstructure of AM Ag925 was characterized by a single-phase silver-rich face-centered cubic solid solution with dendritic morphology, along with some locally distributed micro-segregated copper–germanium (Cu–Ge)-rich regions. Each adjacent dendritic feature consists of Ag–Cu-rich and Ag–Ge-rich regions and appears as alternate dark and bright regions. On the other hand, the as-cast AC Ag925 microstructure comprises Ag and Cu phases. Specific heat treatment was employed, which led to an equiaxed microstructure in AM Ag925 with Cu distributing along grain boundaries while the microstructure of AC Ag925 had Cu precipitates inside the matrix. Bulk texture studies revealed that the solidified textures were very weak for AM Ag925, and a random texture is observed. On the other hand, for the AC Ag925 specimens, a typical fiber texture is observed. Both AC Ag925 and AM Ag925 showed significant deviation from $$\left\langle {100} \right\rangle$$ solidification texture and influences the mechanical properties.

Additive manufacturing (AM) has emerged as an alternative tool to overcome the challenges in conventionally processed metallic components. It is gaining wide acceptability because of the superior properties of the manufactured components compared to their wrought processed counterparts. Among the available AM processed materials, austenitic stainless steel 316L is widely explored wherein an excellent strength-ductility trade-off has been reported. However, the mechanisms underlying fracture toughness of AM stainless steel 316L vis-a-vis wrought processed stainless steel 316L material are not yet explored. The present investigation is aimed at examining the mechanisms accountable for the fracture toughness of AM processed stainless steel 316L. The specimens are produced by two different AM techniques namely, selective laser melting (SLM) and wire arc additive manufacturing (WAAM). A wrought processed stainless steel 316L was used as a control material for comparison. Three-point bending tests were carried out on fatigue pre-cracked single edge notched specimens and crack initiation fracture toughness was evaluated. Digital image correlation was used for strain analysis and to monitor crack propagation. The SLM manufactured sample has shown higher fracture toughness whereas WAAM has exhibited nearly the same fracture toughness when compared to the wrought processed stainless steel 316L sample. Microstructure of fractured samples consists of a significantly higher twin density and a higher propensity of dislocation slip was observed in the SLM sample than the other two. It has been argued that a very fine cellular structure, minimized process-induced defects, enhanced twin density led to promising toughness in the SLM processed stainless steel 316L.

Metal additive manufacturing processes offer unique opportunities for the biomedical industry owing to their ability to produce custom-designed implants with near-net shape and intricate geometry. Co–Cr alloys are among the most popular metallic biomaterials due to their excellent resistance to both corrosion and wear. Several studies have been reported in recent years on studying the processing-structure–property relationships in additively manufactured Co–Cr alloys. However, there is a significant gap in knowledge of critical issues such as the microstructural features and properties of additively manufactured parts as well as the role of the processing parameters and post-manufacturing treatments. The performance of the additively manufactured Co–Cr alloys for biomedical applications such as fatigue, wear, corrosion, and the biological response is poorly characterized as yet. This article presents an overview of the existing literature available on additively manufactured Co–Cr alloys and identifies challenges and opportunities for their use in biomedical implants.

The alloy Ti6Al7Nb with the in situ reinforcement of TiB has been processed by selective laser melting (SLM). Premixed Ti6Al7Nb-xTiB2 powders were used for the powder bed. The microstructure of the Ti6Al7Nb alloy was characterized by martensite (αʹ), while the addition of TiB2 led to a bimodal microstructure with refined features as a result of in situ formation of fine TiB phase. A prismatic ││BD fiber texture was evident in all samples, though the texture formation was found to be affected by the change in the phase transformation pathway due to the formation of TiB. Higher hardness and yield strength (YS) in the composites as compared to the base material are attained. The examination of corrosion response revealed a lower corrosion current (Icorr) value for all the specimens in simulated body fluid (SBF) in comparison to Ti6Al4V alloy. The improved mechanical behavior and better corrosion resistance indicate the potential of SLM-processed Ti6Al7Nb/TiB composite as a suitable replacement for Ti6Al4V alloys for bio-implants.

Thermo-mechanical softening forms the basis for hot working of metallic materials. In materials with hierarchical microstructures such as martensite, softening processes can be mediated or restricted by interfaces. In the present study, the operation of three distinct softening mechanisms in P91 martensitic steel during thermo-mechanical processing (TMP) has been investigated. The softening in the present case is found to arise from the interplay between microstructural strain, texture, and phase transformation. Further, softening characteristics vary with the TMP parameters. The manifestation of softening has been explored at the macroscopic, mesoscopic, and microscopic length scales. It has been found that each softening mechanism is differently mediated by the interfaces and is governed by local crystallographic orientation. Thermo-mechanical softening of martensite proceeds through orientation-dependent dynamic recrystallization. The role of specific interfaces in impeding this mechanism has been highlighted. In contrast, TMP of austenite proceeds through interface-mediated softening, combining the phenomena of recrystallization and phase transformation.

Microstructure evolution and texture development during cold rolling of a Ti15333 alloy were systematically investigated in the present work. Texture was simulated using mean-field [Visco-Plastic Self-Consistent (VPSC) and Taylor] models. Evolution of crystallographic texture was also simulated using the Visco-Plastic Fast Fourier Transform (VPFFT) model. The as-received samples (in the hot-forged and hot-rolled condition) were cold rolled unidirectionally up to 20, 40, 60 and 80 pct thickness reductions. Increase in the cold-rolling reduction resulted in changes in the crystallographic texture as well as grain morphology. The initial hot-rolled sample consisted of in-grain shear bands that were aligned approximately ± 35 to 40 ° with respect to the sample rolling direction. Shear band density gradually increased with the increase in cold-rolling reduction, and these bands usually represent narrow zones of intense strain. α (RD//〈110〉) and γ (ND//〈111〉) fibers were observed in all the cold-rolled samples. The volume fraction of both these fibers was found to be highest for the 80 pct deformed sample. For mean-field simulations, the normalized difference of the texture index (normalized TIdiff) was found to be a good criterion to represent the match between the simulated and experimental texture. The affine model (VPSC) was found to give a good match with the experimental texture compared to the Taylor models. The γ-fiber and α-fiber were always overestimated in mean-field VPSC simulations. Extensive shear band formation could be the possible reason for mismatch between the simulated and experimental texture. For VPFFT simulations, the general texture evolution involved the intensification of the γ-fiber and α-fiber texture. Simulated texture was reasonably well predicted quantitatively with VPFFT, analyzed based on the volume fraction of the different texture fibers/components.

Hot deformation and softening response for the titanium aluminide Ti–48Al–2V–0.2B has been investigated. The deformation response to softening mechanisms has been examined. Deformation experiments were carried out in the strain rate range 0.01–10 s−1 keeping the temperature constant at 1200 °C and in the temperature range 1000–1200 °C at the strain rate 1 s−1. With an increase in strain rate, the microstructural changes associated with the softening mechanism include breaking of the lamellae, spheroidization of the broken laths and dynamic recrystallization. For the strain rate 1 s−1, deformation in the (α2 +γ) phase field leads to fine recrystallized grains, remnant lamellae and cavitation along the grain boundaries (for temperatures 1000 and 1100 °C). Deformation in the (α +γ) phase field leads to dynamic recrystallization at the shear bands, within the lamellae, breaking and rotation of the α phase during the continuous increase in the deformation strain.

In the present investigation, the evolution of texture and microstructure during incremental sheet forming was investigated. Hot-rolled sheets of commercially pure titanium were subjected to single-point incremental forming to obtain truncated pyramid geometries. It was observed from texture measurements that there was splitting of basal poles along the transverse direction. Moreover, a significant number of twins was observed in the deformed microstructure with the fraction of extension twins being highest compared to other variants. The crossing of deformation twins, formation of twin lamellar structure and formation of secondary extension twins within primary contraction twins were additionally observed. The state of deformation in the pyramid walls was analyzed via finite element method which in turn was used as input for carrying out crystallographic texture simulations via visco-plastic self-consistent simulations. It was observed that the state of deformation in the wall regions is plain strain compression plus through-thickness shear.

In the present study, the Fe-Al-based compositions developed as low-density steel are subjected to addition of Cr and Mn to increase the elastic modulus. In this regard, Fe-3.7Al-3.1Mn and Fe-6.5Al-6.3Cr steels are produced via melting and casting. The steels are cold-rolled to 98% thickness reduction followed by subsequent annealing at 750 °C. A detailed characterization based on x-ray diffraction and electron back-scattering diffraction shows the stabilization of ferrite phase upon the addition of Cr and Mn with a further reduction in density. The expansion of the lattice is observed after ternary alloying additions. The increase in the yield stress and ultimate tensile strength is noticed upon ternary alloying additions. The Cr and Mn addition also led to an increase in the elastic modulus compared to binary Fe-Al low-density steels.

In this investigation, the superalloy IN718 has been prepared by additive manufacturing (AM) following a selective laser melting technique, and the post-AM heat treatments have been optimized. The microstructure of additively manufactured (AM) IN718 is characterized by the presence of dendritic and cellular features with large spatial heterogeneity along and across the build plane. Along the build direction, the fiber texture dominates. Heat treatment involving two-step solution treatment, and subsequently, two-step aging treatment was specifically designed to facilitate the precipitation of d phase at the grain boundaries to make the material resistant to grain boundary sliding (GBS). The AM IN718 showed dynamic strain aging (DSA) at three different temperatures, while the critical strain for the onset of serration was extended to a higher value after the heat treatment.

Ti-Nb-based low modulus metastable β-titanium alloys are popular choice for orthopedic implant materials. The performance of these materials could be affected by variation in crystallographic texture developed during processing. In the present study, texture evolution during unidirectional rolling and multi-step cross-rolling of the alloys Ti-34Nb-2Ta-3Zr-0.5O (TNTZO) and Ti-34Nb-2Ta-0.5O (TNTO) (in wt pct) has been studied. In both the alloys, the rolling texture is characterized by the absence of RD∥〈110〉 fiber, and cross-rolling leads to a stronger texture than unidirectional rolling. However, the prominent texture components in the cross-rolled condition are different for the two alloys. The TNTZO alloy shows the formation of a strong γ-fiber (ND∥〈111〉) along with {001}〈110〉 components while in TNTO, the texture is dominated by strong {001}〈110〉 component. These experimental results have been analyzed by simulations using viscoplastic self-consistent model and further validated by microstructural analysis using electron back scattered diffraction (EBSD). The deformation texture evolution has been attributed to a predominantly $$ \left\{ {11\overline{2} } \right\}\left\langle {111} \right\rangle $$ slip. The simulated texture of Ti-34Nb-2Ta-0.5O alloy shows a minor deviation from the experimental texture, which can be related to the reduced stability of this alloy due to the absence of Zr.

The formation of shear bands during hot deformation of a two-phase (α2 + γ) titanium aluminide and its consequences on dynamics softening has been investigated. The starting material consists of a colony of lamellar grains along with the segregated vanadium and niobium which was subjected to hot deformation in the temperature range 1000–1175 °C at the strain rate 10 s−1. Microstructures of the deformed samples indicate that, with increase in the deformation temperature, the orientation of shear bands changes. Moreover, the extent of dynamic recrystallization also increases with deformation temperature. The softening behaviour and crystallographic orientation change within lamellae during hot deformation have been explored. The nucleation of newly recrystallized grains has been observed at twin–parent grain boundary and within the twined γ phase. Lamellae of the γ and α2 phase have been also observed to be twisted and tilted, leading to the band formations under the load, whose mechanisms have also been explored in the present study.

In this study, mechanical properties and microstructural investigation of Ti64 at high strain rate are studied using a split-Hopkinson pressure bar method under compression for temperatures up to 800 °C. Flow softening in the mechanical response of material to such loading conditions hints at instability in compression, which increases with an increase in temperature. Microstructural characterization of the deformed material is characterized using the electron-backscattered diffraction technique. It reveals the presence of instabilities in Ti64 in the form of a fine network of shear bands. The shear band width grows with an increase in temperature along with the area fraction of shear band in the material, displaying its improved capacity to contain microstructural instabilities at higher temperature. After a detailed microstructural investigation, a mechanism for shear band widening is proposed. Based on this mechanism, a path generating nuclei within shear bands is discussed.

The effect of ternary zinc (Zn) addition to two-phase magnesium-lithium alloys on the evolution of their microstructure, texture and tensile properties has been investigated. It was observed that the volume fraction of hexagonal close-packed α phase increased with increase in the Zn content. The size of α lamellae reduced with increase in the Zn content. The strength of the alloys in as-cast condition increased with the Zn content due to solid-solution strengthening without compromising the ductility. The tensile properties of these two-phase alloys were found to be strongly dependent on the volume fraction and size of the α phase. Zn addition led to enhancement of the {200} || normal direction (ND) component but weakening of {110} || ND components in the β phase, while increase in the Zn content had a minor effect on the texture of the α phase in cold-rolled condition. The specific strength of the alloy with 2 wt.% Zn was found to be comparable to, while the ductility was higher than, the highest-strength 7075-T73 Al alloy.

This study deals with the evolution of crystallographic texture during secondary processing of aluminium-lithium alloy AA2195 sheets and its effect on the single-point incremental forming (SPIF) process. Significantly different textures were generated in AA2195 alloy sheets by the unidirectional rolling (UDR) and multi-step cross-rolling (MSCR) processes followed by subsequent annealing. The differently textured sheets were then subjected to the SPIF process. For UDR processed sheets, the texture was the strong copper type (Cu-type), whereas in MSCR processed sheets, the texture comprised weak fibres. The UDR samples with strong texture experienced cracking during incremental forming, whereas the MSCR samples could be formed without any cracks. Detailed analyses of the microstructure and texture were performed at various locations on the incrementally formed part to understand the deformation micromechanism at specific locations on the formed component.

Additively manufactured alloys produced by selective laser melting (SLM) exhibit different microstructure, texture and mechanical properties compared to their conventionally processed counterparts. The reason for this difference has been attributed to unique conditions that are met during processing through SLM. The differences are specific to the alloy system. Most influencing variable of SLM processing has been found to be the scanning strategy which comprises interlayer hatch rotation, build orientation, printing pattern (unidirectional, meander or checker board), etc. These variants lead to alteration of microstructure and crystallographic texture. Among the properties, yield strength of SLM-processed alloys has been found to be higher compared to their conventionally processed counterparts, which has been attributed to the finer microstructure and high defect density resulting from the process. On the other hand, ductility is on the lower side due to voids and porosity. The texture of SLM-processed materials shows characteristic features, which is dependent on materials and processing strategies. This further influences the properties. This paper deals with the evolution of microstructure, texture and mechanical properties for selected alloy systems, namely the alloys of iron, aluminium, and titanium, which have been most extensively studied after SLM processing.

The hot deformation response of third-generation titanium aluminides with compositions Ti-45Al-5Nb-0.2B-0.2C and Ti-45Al-10Nb-0.2B-0.2C (hereafter referred to as Ti-45-5 and Ti-45-10, respectively) has been investigated through isothermal compression tests. The tests have been carried out in the $$ (\alpha_{2} + \gamma ) $$ and $$ (\alpha + \gamma ) $$ phase regions for both alloys. The flow response, kinetics and microstructural evolution during hot deformation have been analysed in detail, and the outcome of the investigation has been used to predict the processing window for the two alloys. The optimum processing domain for the Ti-45-10 alloy is situated 50°C higher than that of the Ti-45-5 alloy. The post-mortem analyses of the microstructures revealed that deformation in the $$ (\alpha_{2} + \gamma ) $$ phase field leads to dynamic recrystallisation of all the phases resulting in a distribution of very fine grains. Microstructural features of both alloys depict kinking and breaking of the lamellae for the equivalent temperatures. The higher strength of the Ti-45-10 alloy has been attributed to shifting of the order-disorder transition toward the higher temperature side. In the $$ (\alpha + \gamma ) $$ region, the fraction of $$ \alpha $$ phase increases more for the Ti-45-10 alloy compared with the Ti-45-5 alloy.

In this study, the effect of aluminum (Al) addition to a manganese (Mn) steel Fe-12Mn-0.5C in regard to the change in stacking fault energy (SFE) and the consequent evolution of deformation microstructure and texture were investigated during cold rolling. An analysis of the texture and microstructure was performed to understand the deformation micro-mechanisms. Deformation micro-mechanisms were substantiated by the estimation of dislocation density and the arrangement of dislocations in the deformed microstructure by X-ray line profile analysis, which revealed significant changes in the dislocation structure with the addition of Al. Three stages of deformation mechanism were observed in all Al-added compositions. In the early stages of deformation, slip as well as twinning prevailed. In the intermediate stage, twinning took over completely and at large strains, macroscopic shear bands became the dominant deformation mode. An increase in the propensity of nanometer-sized deformation twins was observed with rolling strain. However, the addition of Al decreased the overall twin fraction in the deformed microstructure. The theoretical twinning stress was calculated to explain the crucial role of SFE on the occurrence of deformation twins in these steels. The deformation texture was predominantly of the brass type for all the Al-added compositions; however, appreciable differences were seen with Al content. The 〈111〉//ND γ-fiber, which develops in Al-free Fe-12Mn-0.5C, completely disappeared in 3 wt pct Al-containing material.

In the present study, hot deformation behavior of a FCC high-entropy alloy CoCuFeMnNi has been investigated to explore the stress-strain response for a wide range of temperatures and strain rates. The deformation response has been examined by plotting a processing map and examining the evolution of microstructure and texture in each of the temperature-strain rate domain. Hot compression tests were carried out in the temperature range 850-1050 degrees C at strain rates varying from 0.001 s(-1) to 10 s(-1). Stress-strain curves indicate characteristic softening behavior due to dynamic recrystallization (DRX). DRX has been observed along grain boundaries, shear bands, as well as in the interior of deformed grains. The size of dynamically recrystallized grains shows a strong dependence on deformation temperature and increases with temperature. A high degree of twin formation takes place in the DRX grains evolved inside the shear bands, and the extent of twinning decreases at high temperatures. The optimal processing window has been estimated based on strain rate sensitivity and has been validated with detailed analyses of microstructure and texture. The best region for thermo-mechanical processing has been identified as in the temperature range 850-950 degrees C at strain rate 10(-1) s-1.

In the present investigation, a systematic study of the evolution of microstructure and crystallographic texture during hot deformation of Nb-1Zr-0.1C was carried out in the temperature range 1773-1973K (1500-1700 degrees C) at different strain rates of 0.001, 0.01 and 0.1s(-1). The aim was to examine the mechanisms of dynamic recovery and recrystallization in a high-temperature range. A detailed microstructural analysis of the deformed samples was performed using the electron backscatter diffraction technique to study the occurrence and nature of various dynamic restoration processes; the different regimes of dynamic recovery and recrystallization were identified. The orientations of the dynamically recrystallized grains were found to be (001) .

Aerospace-grade Ni-based alloys such as Inconel 718 and 625 are widely used in the airspace industry thanks to their excellent mechanical properties at high temperatures. However, these materials are classified as difficult-to-machine' because of their high shear strength, low thermal conductivity, tendency to work-harden and presence of carbide particles in their microstructure, which lead to rapid tool wear. Machining-induced residual stresses in a machined part is an important parameter which is assessed since it can be used to evaluate overall structural resilience of the component and its propensity to fatigue failure in-service. Ultrasonically assisted turning (UAT) is a hybrid machining technique, in which tool-workpiece contact conditions are altered by imposing ultrasonic vibration (typical frequency similar to 20kHz) on a tool's movement in a cutting process. Several studies demonstrated successfully the resulting improvements in cutting forces and surface topography. However, a thorough study of UAT-induced residual stresses is missing. In this study, experimental results are presented for machining Inconel 718 and 625 using both conventional turning (CT) and UAT with different machining parameters to investigate the effect on cutting forces, surface roughness and residual stresses in the machined parts. The study indicates that UAT leads to significant cutting force reductions and improved surface roughness in comparison to CT for cutting speeds below a critical level. The residual stresses in machined workpiece show that UAT generates more compressive stresses when compared to those in CT. Thus, UAT demonstrates an overall improvement in machinability of Inconel alloys.

In dissimilar friction stir welding (FSW), the presence of a third interlayer material can have a positive influence on local ternary chemical reactions due to complex mechanical mixing in the weld nugget. This leads to a reduction and distribution of intermetallic compounds as fine particles in the weld nugget. These fine particles can provide high-temperature grain stability. In the present investigation, a zinc (Zn) interlayer was used during the FSW of aluminum (Al) with titanium (Ti). X-ray computed tomography results revealed the occurrence of mechanical mixing of Zn with both Al and Ti. To understand the nature of the weld nugget at high temperatures, heat treatment of the weld was carried out at 500 degrees C for 60min. The detailed mechanisms leading to the superior grain stability of Al in the weld nugget were investigated. The improvement in grain stability of Al may open up a new area of research and development to produce new materials with high-temperature grain stability.

This investigation highlights the influence of tool offset on the microstructural evolution, phase formation, and hardness distribution during friction stir welding (FSW) of commercially pure aluminum (Al) to commercially pure titanium (Ti) with a copper (Cu) interlayer (200-μm thick). It was observed that tool offset position controls the mechanical mixing of materials in the weld nugget. The mechanical mixing also depends on the deformation, fragmentation, and distribution of each material in the weld nugget. The fragmentation of materials leads to the development of comparatively fine particles with variation in size and morphology. Insufficient mixing at higher tool offsets promotes the formation of root defects and produces inferior welds. On the other hand, when the tool offset is less than the optimum value, severe deformation and mechanical mixing lead to the formation of wormhole defects and evolution of intermetallic compounds in the weld. The spatial distribution of particles and intermetallics in the weld nugget leads to a large scatter in hardness values. Since mechanical mixing affects the morphology, phase evolution, and mechanical properties of the weld, tool offset is considered to be a very important parameter to be optimized for monitoring mechanical mixing and further development of the dissimilar weld with interlayer material.

Inconel 718 is a precipitation-strengthened Ni-based superalloy which finds applications across a wide temperature range (up to 650°C). It shows excellent yield strength, ductility, creep resistance and fatigue strength. Surface treatment is known to improve the fatigue life of materials via nano-crystallization of the surface layer. However, the precipitation behavior of the surface-treated layer is largely unexplored. In this regard, the present study aims to investigate and compare the precipitation in the surface-treated layer and the bulk solution-treated IN718. The material is subjected to surface mechanical attrition treatment (SMAT) after solution treatment and is followed by a two-step aging treatment which promotes the precipitation of γ″/γ′ in the alloy. The precipitation behavior shown by the bulk and SMAT layer was different. After aging, the bulk shows a microcrystalline γ matrix containing γ″ precipitates, whereas the microstructure of the surface layer consists of nanograins with nanotwins. No evidence of γ″/γ′ precipitates were observed in the SMAT layer. The formation of nanograins in the surface layer after aging is attributed to recrystallization with controlled grain growth. The differential microstructures due to the chosen processing route have resulted in increased hardness of the surface layer and increased wear life of the material.

The present study investigates the possibility of enhancing the strength with ductility of dual-phase magnesium (Mg)-8 lithium (Li) alloy by the combination of alloying addition aluminium (Al) and suitable thermo-mechanical processing. Microstructural evolution, phase analysis and texture studies were performed for Mg-8Li-xAl (x = 0, 2,4 and 6) alloys with the help of scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is understood from the texture studies that the addition of Al to the Mg-8Li alloys activates the non-basal slip at room temperature. In turn, it facilitates the recovery process, hence a substantial improvement in plastic deformation after annealing of the alloys is observed. This is attributed to non-basal slip activity at room temperature. The presence of fine intermetallic compounds in the annealed Mg-8Li-xAl (x = 4 and 6) alloys leads to the higher ultimate strength (193 +/- 7 MPa and 267 +/- 9 MPa) and ductility (20% and 17%), respectively. (c) 2018 Politechnika Wroclawska. Published by Elsevier B.V. All rights reserved.

Microstructure and crystallographic texture evolution during single- and multiple-pass friction stir processing (FSP) of an age-hardenable aluminum alloy 2024 (Al-Cu-Mg) was investigated. Multiple-pass experiments were carried out using two different processing strategies, multi-pass FSP, and multi-track FSP. Effect of a post-FSP heat treatment above and below the solutionizing temperature of the alloy was also studied. FSP experiments were carried out using an optimal set of parameters. Characterization tools used in the study include scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), electron probe micro-analyser (EPMA), and X-ray diffraction (XRD). Microstructural features indicate the occurrence of particle stimulated nucleation (PSN) assisted dynamic recrystallization (DRX) as the dominant microstructural evolution mechanism in the nugget zone. Geometrical coalescence occurred, leading to the formation of some larger grains in the nugget zone. Heterogenous micro-texture distribution was observed in the nugget zone with the bulk textures consisting of FCC shear texture components dominated by A (1)*/A (2)* and C. Microstructure and texture in the nugget zone remained stable after both routes of multiple-pass processing, demonstrating the possibility of FSP to produce bulk volume of fine-grained materials. Post-FSP heat treatment indicated the stability of microstructure and texture up to 723 K (450 A degrees C) owing to relatively lower strain energies retained after FSP.

Microstructural and crystallographic aspects of high-velocity forming or ``rapid'' forming of rolled sheets of pure copper have been investigated in this work. Significant changes in crystallographic orientation and microstructure were observed when thin (0.5 mm) metal sheets of annealed copper were subjected to high strain rate deformation in a conventional shock tube at a very low impulse magnitude (similar to 0.2 N s), which is inconceivable in conventional metal forming. Shock-loaded samples show characteristic texture evolution with a high brass {110} < 112 > component. A significant change in grain orientation spread was observed with increasing amount of effective strain without any drastic change in grain size. The texture after deformation was found to be strain-dependent. The path of texture evolution is dependent on the initial texture. Misorientation was limited to less than 5 degrees. Deformation bands and deformation twins were observed. There was a decrease in twin Sigma 3 coincidence site lattice (CSL)] boundary number fraction with increasing strain due to the change in twin boundary character to high-angle random boundary (HARB) as a result of dislocation pile up. The study shows the probability of a high-velocity shock wave forming pure Cu.

Highly oriented Ni–Mn–Ga thin film with multiple variants and room temperature orthorhombic martensite structure were prepared on a single crystalline Al2O3 $\left({11\bar 20} \right)$ substrate by DC magnetron sputtering. X-ray diffraction and rocking curve measurements reveal the film as (202)7M oriented with an excellent crystal quality (Δω = 1.8°). Spot-like pole figures indicate that the Ni–Mn–Ga film grows with a strong in-plane preferred orientation. An in-depth analysis of the measured pole figure reveals the presence of a retained austenite phase in the film. Two phase transformations, MS ∼345 K and TC ∼385 K, are observed and are attributed to first order structural transformation from cubic to orthorhombic, and second order phase transformation from ferromagnetic to paramagnetic, respectively. In situ high temperature x-ray diffraction measurements provide a clear indication of a thermally-induced martensite ↔ austenite reversible structural phase transformation in the film. The presence of martensite plates with seven modulated orthorhombic structure and adaptive nano-twins are some of the important microscopic features observed in the film with transmission electron microscopy investigations.

P.G thanks Department of Science and Technology, Govt. of India (SR/S4/FS-481/2009), Ministry of Earth Sciences (MoES/ATMOS/PP-IX/09), Divecha Centre for Climate Change, Australian Scientifc Instrument and I.W thanks Australian Scientifc Instrument for funding the project.

In the current study, correlation of microstructure evolution with bulk crystallographic texture formation during friction stir processing (FSP) of commercial aluminum alloys has been attempted. Electron back-scattered diffraction and X-ray diffraction techniques were employed for characterizing the nugget zone of optimum friction stir processed samples. Volume fraction of measured texture components revealed that the texture formation in aluminum alloys is similar irrespective of the alloy composition. Recrystallization behavior during FSP was more of a composition dependent phenomenon.

Pure magnesium is subjected to cold rolling followed by annealing at 200 °C to obtain near-equiaxed grains of average grain size ~15 µm. The hardness of different grains/orientations of the annealed samples is estimated through consecutive characterization by nanoindentation and electron backscattered diffraction. It is observed that an increase in deviation from basal orientation decreases the hardness of an orientation. Orientations

Friction-stir processing (FSP) has been proven as a successful method for the grain refinement of high-strength aluminum alloys. The most important attributes of this process are the fine-grain microstructure and characteristic texture, which impart suitable properties in the as-processed material. In the current work, FSP of the precipitation-hardenable aluminum alloy 2219 has been carried out and the consequent evolution of microstructure and texture has been studied. The as-processed materials were characterized using electron back-scattered diffraction, x-ray diffraction, and electron probe microanalysis. Onion-ring formation was observed in the nugget zone, which has been found to be related to the precipitation response and crystallographic texture of the alloy. Texture development in the alloy has been attributed to the combined effect of shear deformation and dynamic recrystallization. The texture was found heterogeneous even within the nugget zone. A microtexture analysis revealed the dominance of shear texture components, with C component at the top of nugget zone and the B and A(2)* components in the middle and bottom. The bulk texture measurement in the nugget zone revealed a dominant C component. The development of a weaker texture along with the presence of some large particles in the nugget zone indicates particle-stimulated nucleation as the dominant nucleation mechanism during FSP. Grain growth follows the Burke and Turnbull mechanism and geometrical coalescence.

The effect of strain path change during rolling on the evolution of deformation texture has been studied for nanocrystalline (nc) nickel. An orthogonal change in strain path, as imparted by alternating rolling and transverse directions, leads to a texture with a strong Bs {110}aOE (c) 112 > component. The microstructural features, after large deformation, show distinct grain morphology for the cross-rolled material. Crystal plasticity simulations, based on viscoplastic self-consistent model, indicate that slip involving partial dislocation plays a vital role in accommodating plastic deformation during the initial stages of rolling. The brass-type texture evolved after cross rolling to large strains is attributed to change in strain path.

Density reduction of automotive steels is needed to reduce fuel consumption, thereby reducing greenhouse gas emissions. Aluminum addition has been found to be effective in making steels lighter. Such an addition does not change the crystal structure of the material. Steels modified with aluminum possess higher strength with very little compromise in ductility. In this work, different compositions of Fe-Al systems have been studied so that the desired properties of the material remain within the limit. A density reduction of approximately 10% has been achieved. The specific strength of optimal Fe-Al alloys is higher than conventional steels such as ultra-low-carbon steels.

A Cu-Cu multilayer processed by accumulative roll bonding was deformed to large strains and further annealed. The texture of the deformed Cu-Cu multilayer differs from the conventional fcc rolling textures in terms of higher fractions of Bs and RD-rotated cube components, compared with the volume fraction of Cu component. The elongated grain shape significantly affects the deformation characteristics. Characteristic microstructural features of both continuous dynamic recrystallization and discontinuous dynamic recrystallization were observed in the microtexture measurements. X-ray texture measurements of annealing of heavily deformed multilayer demonstrate constrained recrystallization and resulted in a bimodal grain size distribution in the annealed material at higher strains. The presence of cube- and BR-oriented grains in the deformed material confirms the oriented nucleation as the major influence on texture change during recrystallization. Persistence of cube component throughout the deformation is attributed to dynamic recrystallization. Evolution of RD-rotated cube is attributed to the deformation of cube components that evolve from dynamic recrystallization. The relaxation of strain components leads to Bs at larger strains. Further, the Bs component is found to recover rather than recrystallize during deformation. The presence of predominantly Cu and Bs orientations surrounding the interface layer suggests constrained annealing behavior.

The first part of this study describes the evolution of microstructure and texture in Ti-6Al-4V-0.1B alloy during sub-transus rolling vis-a-vis the control alloy Ti-6Al-4V. In the second part, the static annealing response of the two alloys at self-same conditions is compared and the principal micromechanisms are analyzed. Faster globularization kinetics has been observed in the Ti-6Al-4V-0.1B alloy for equivalent annealing conditions. This is primarily attributed to the α colonies, which leads to easy boundary splitting via multiple slip activation in this alloy. The other mechanisms facilitating lamellar to equiaxed morphological transformations, e.g., termination migration and cylinderization, also start early in the boron-modified alloy due to small α colony size, small aspect ratio of the α lamellae, and the presence of TiB particles in the microstructure. Both the alloys exhibit weakening of basal fiber (ND||〈0001〉) and strengthening of prism fiber (RD||〈 $$ 10\bar{1}0 $$ 〉) upon annealing. A close proximity between the orientations of fully globularized primary α and secondary α phases during α → β → α transformation has accounted for such a texture modification.

In the current study, the evolution of microstructure and texture has been studied for Ti-6Al-4V-0.1B alloy during sub-transus thermomechanical processing. This part of the work deals with the deformation response of the alloy by rolling in the (α + β) phase field. The (α + β) annealing behavior of the rolled specimen is communicated in part II. Rolled microstructures of the alloys exhibit either kinked or straight α colonies depending on their orientations with respect to the principal rolling directions. The Ti-6Al-4V-0.1B alloy shows an improved rolling response compared with the alloy Ti-6Al-4V because of smaller α lamellae size, coherency of α/β interfaces, and multiple slip due to orientation factors. Accelerated dynamic globularization for this alloy is similarly caused by the intralamellar transverse boundary formation via multiple slip and strain accumulation at TiB particles. The (0002)α pole figures of rolled Ti-6Al-4V alloy shows “TD splitting” at lower rolling temperatures because of strong initial texture. Substantial β phase mitigates the effect of starting texture at higher temperature so that “RD splitting” characterizes the basal pole figure. Weak starting texture and easy slip transfer for Ti-6Al-4V-0.1B alloy produce simultaneous TD and RD splittings in basal pole figures at all rolling temperatures.