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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.

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 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.

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.

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.

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.