DSpace Collection:

A STUDY ON TUNGSTEN OXIDE REDUCTION FOR TUNGSTEN POWDER PRODUCTION

2026-05-11T06:45:47Z

Title: A STUDY ON TUNGSTEN OXIDE REDUCTION FOR TUNGSTEN POWDER PRODUCTION Authors: Tomar, Varun Abstract: Hydrogen reduction is one of the most common and important methods to manufacture tungsten powders from WO3. Several developments have been made to manufacture ultrafine tungsten particles by hydrogen reduction. However, controlling particles size during formation of tungsten particles is rather a difficult process as WO2(OH)2 inevitably forms during the process resulting in increasing the particle size. In this study a new method to produce micron sized tungsten particles was investigated. WO3 powders were reduced by hydrogen reduction after milling them for 2, 4, 6 and 8 hours. The resultant particles were characterized to determine their size and phases present in them.

KINETIC MONTE CARLO SIMULATION OF DISLOCATION SOLUTE INTERACTIONS IN MULTI COMPONENT ALLOYS

2026-05-11T06:04:15Z

Title: KINETIC MONTE CARLO SIMULATION OF DISLOCATION SOLUTE INTERACTIONS IN MULTI COMPONENT ALLOYS Authors: Macharla, Pardhu Chandra Abstract: In Co-based superalloys, high temperature deformation is controlled by glide of dislocations with a solute atmosphere around them [1]. A gain in strain energy drives the formation of the solute clouds which are kinetically controlled by atomic diffusion. As the drag offered by the solute atmospheres to dislocation motion at elevated temperatures determine the rates of creep deformation, it is essential to do a detailed study of dislocation motion when the solute atoms are diffusing and interacting with the dislocations. A Kinetic Monte Carlo model is developed to simulate edge dislocation motion in the presence of solute atoms that are diffusing and interacting with it through their respective strain fields. Our simulations can determine the dislocation velocity and solute concentration profile around the dislocation self-consistently. At low velocity the moving dislocation will be associated with a solute atmosphere, while at high velocity no solute clouds will form. Through our simulations, we predict the degree of solute cloud formation around the edge dislocation and develop the functional relationship between its velocity and resolved shear stress on the glide plane. We also derive qualitative guidelines from our simulations which can be used to design novel creep resistant alloys.

EFFECT OF STRAIN RATE ON THE EVOLUTION OF MICROSTRUCTURE OF DEFORMED TI-15V-3CR-3SN-3AL ALLOY

2026-05-11T06:04:04Z

Title: EFFECT OF STRAIN RATE ON THE EVOLUTION OF MICROSTRUCTURE OF DEFORMED TI-15V-3CR-3SN-3AL ALLOY Authors: Saichandu, Sampathirao Abstract: Ti-15V-3Cr-3Al-3Sn (Ti-15-3) is a metastable β alloy which has good formability, high strength to weight ratio, desirable corrosion resistance, and excellent fatigue resistance. This alloy is mainly used in many aircfraft components. The role of strain rate on the deformation behaviour and microstructural changes in beta titanium alloys is not well documented. The understanding of the role of strain rate on microstructural changes and micromechanisms of deformation is crucial to efficiently select the processing route such as forging, rolling, extrusion etc.Therefore, the present study aims to understand the role of strain rate during room temperature deformation on the deformaton behavior and the microstructural changes. The Ti-15-3 alloy was compressively deformed at room temperature for different strain rates ranging from 0.001 s-1 to 3 s-1. All the samples are characterized in a FE-SEM to observe the deformation characteristics. Deformation bands of varying intra-grain misorientations were observed. Transition bands comprising severe microstrain is observed inbetween the deformation bands. X-ray diffraction and electron backscattered difraction (EBSD) studies were carried out to evaluate the extent of microstrain and their orientation dependance. The grains with high intra grain misorientations were mostly <001> oriented grains, while low intra-grain misorientation regions comprised both <001> and <111> oriented grains. The local mechanical properties were characterized using nano-indentation measurements.

GAS NITRIDING OF ZIRCALOY 4

2026-05-11T06:03:55Z

Title: GAS NITRIDING OF ZIRCALOY 4 Authors: Kumar, Rishabh Raj Abstract: Gas nitriding of Zircaloy-4 as received sample was done in nitrogen atmosphere at 800oC for 4 hours. Nitrded sample was characterized by XRD, Optical microscope and Vicker’s Microhardness test was done on the specimen. Porous, cracked and anisotropic oxide layer was formed on the surface as well as ZrN was formed in metal-oxide interface. Oxygen stabilized alpha zirconium was also formed near the substrate. The hardness of layer is found out to be 1650HV0.01 as compared to the substrate hardness of 209 HV0.01.