000			02327nam a22001697a 4500
082			_a620.112 _bG977O
100			_aGupta, Sandeep Das _926624
245			_aOn the Scaling of Fracture Toughness with Relative Density in Sintered Alumina _cby Sandeep Das Gupta
260			_aIIT Jodhpur _bDepartment of Metallurgical & Materials Engineering _c2020
300			_axvi,39p. _bHB
520			_aAmong boron-rich solids boron carbide come third in hardness when compared to diamondlike structures and has been the subject of research in recent decades. They possess superior industrial manufacturability, low density, and high hardness as compared to other ceramics such as alumina and silicon carbide. Despite of these properties, an ordinary pernicious attribute called “pressure-induced softening", limits their performance in high-velocity projectile applications. This thesis highlights this characteristics of amorphized states of boron carbide, an ordinary icosahedral boron-rich ceramic, intending to understand the mechanistic layout of this softening. Shock studies of B4C have suggested phase transformation at high pressures, but to date, no convincing proof has been affirmative to prove the existence of new high-pressure phases. To help uncover the failure mechanism, we used methods based on ab-intio calculations to carry out a simulation on B11C-CBCp polytype, results of which is later compared to B12-CCC stoichiometric boron carbide. For structural characterization, we have calculated non-resonant Raman spectra, which has been evaluated using first-principles calculations considering the macroscopic view of Raman Spectra. Our simulation suggests that softening is the consequence of structural changes associated with the three-atom chain’s bending. Carefull analysis of the calculated Raman spectra suggested shifts in the peak position and intensity with the variation of pressure. Calculations of the elastic constants (Ci jkl) are also being carried out following a homogeneous deformation method, to understand its mechanical behaviour under pressure variation.
650			_aToughness with Relative Density in Sintered Alumina _926625
650			_aMTech Theses _926626
650			_aDepartment of Metallurgical & Materials Engineering _926627
700			_aBhattacharyya, Abir _926628
942			_cTH
999			_c14787 _d14787