Ashok Kumar Singh

Structure of the B2 phase in the Ti-25Al-25Zr alloy: a density functional study.

We report a first-principles density functional theory study of the B2 phase structure in the Ti-25Al-25Zr alloy. Several structural models with different site occupancies have been investigated. In the ideal B2 phase, the Zr atom is found to preferentially occupy the Ti site. However, if the atoms are allowed to relax, Zr occupies both Ti and Al sites, leading to local positional disorder in the structure due to the large size differences of the constituent elements. Further, this alloy is predicted to have better room temperature ductility, enhancing its utility in several technological applications.

Thermal and Mechanical Stability of the Single Component Rotated Brass Texture in a 7010 Aluminum Alloy

The stability of a unique single, rotated Brass-{110}á556ñ component developed in a Al-Zn-Mg-Cu based 7010 alloy, during long term thermal annealing and cold rolling deformation has been systematically investigated. It is observed that this component remains stable during annealing at 465 °C over the period of 96 hrs and up to a uniaxial cold rolling reduction of 60%. The thermal and mechanical stability of the single component texture is discussed in terms of preferential growth advantage of recrystallized grains and confinement of slip activity in two major slip systems, respectively.

Effect of Roll Diameter and Modes of Rolling on Evolution of Texture in High Purity Aluminum

Present work describes the development of texture in high purity aluminum under different modes of deformation by rolling using two different roll diameters, namely 300 and 610 mm. It has been observed that the change in both the roll diameter as well as the modes of rolling has a marked influence on the evolution of texture as well as the characteristics of a- and β-fibres. The results are discussed in terms of the effects of roll gap geometry and the relevant stress conditions that affect the strain path of crystallite rotation.

Mechanical Property Anisotropy of 7010 Aluminum Alloy Sheet Having Single Rotated-Brass Texture

Mechanical property anisotropy in terms of in-plane anisotropy (AIP) of yield strength, and work hardening behavior of a heat treated 7010 aluminum alloy sheet has been investigated. The specimens were given two different types of heat treatments that result in a unique single rotated Brass-{110}á556ñ component with different texture intensity and volume fraction of recrystallization. It has been observed that the AIP increases with increase in texture intensity and volume fraction of recrystallization. The results are discussed on the basis of Schmid factor analyses in conjunction with microstructural features namely, grain morphology and precipitation. On the other hand, work hardening behavior appears to be significantly affected by the microstructural features rather than type of texture present in the samples.