S. Banumathy
Defence Metallurgical Research Laboratory
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Featured researches published by S. Banumathy.
Smart Materials Research | 2012
J. Arout Chelvane; Mithun Palit; Himalay Basumatary; S. Banumathy; A. K. Singh; S. Pandian
Effect of V addition on the microstructure and magnetostriction of directionally solidified Tb0.3Dy0.7Fe1.95 has been investigated. The microstructure of V added alloys (Tb0.3Dy0.7 with , 0.025, 0.05, and 0.075) indicate that Fe-50 at.% V is formed as primary phase, which subsequently undergoes spinodal decomposition. The spinodially decomposed Fe-rich phase reacts with the liquid and forms the matrix phase, (Tb,Dy)Fe2. The V-rich spinodally decomposed product, on the other hand, exists as remnant phase without undergoing any metallurgical transformation. Texture studies indicate that the grains of (Tb,Dy)Fe2 show /rotated and orientations for all compositions investigated in the directionally solidified condition. An improvement in magnetostriction has been noticed for small addition of V and with further addition the magnetostrictive property decreases. The formation of additional phases containing vanadium is attributed to be the reason when V is added in higher concentration levels.
Materials Science Forum | 2011
S. Banumathy; R.K. Mandal; A. K. Singh
This work describes the development of texture during hot rolling of two alloys namely, Ti-12Nb and Ti-16Nb. The alloys have been unidirectionally hot rolled to 80 % reductions at 800°C and air cooled. Both the alloys show the presence of a² (orthorhombic) and small volume fraction of b (bcc) phases in hot rolled condition. The alloy Ti-12Nb exhibit moderate intensity texture while the alloy Ti-16Nb displays quite strong texture. The high overall intensity of texture in alloy Ti-16Nb in 80 % HR specimen can be attributed to the presence of large volume fraction of b phase in comparison to that of the alloy Ti-12Nb. This has been extended to study the textural changes after b solution treatment. This heat treatment consists of two types of phase transformations that are a² ® b ® a² and a² ® b ® a after water quenching and furnace cooling from β phase field.
Materials Science Forum | 2011
J. Arout Chelvane; Mithun Palit; Himalay Basumatary; S. Banumathy; A. K. Singh; S. Pandian
This paper reports the effect of Ho on the microstructure, texture and magnetostrictive properties of Tb0.3Dy0.7-xHoxFe1.95 (with x = 0, 0.05, 0.1, 0.15 and 0.2) alloys. The alloys were vacuum induction melted and directionally solidified by modified Bridgman technique. Ho addition has been found to improve the magnetostriction at lower concentration due to absence of deleterious pro-peritectic (Tb,Dy)Fe3 phase. The static strain co-efficient is found to be better in Ho added alloys and the prevalence of strong and texture is attributed to be the reason.
Materials Science Forum | 2011
S. Banumathy; R.K. Mandal; A. K. Singh
The present work describes the study of mechanical properties anisotropy of two binary alloys namely, Ti-8Nb and Ti-12Nb in hot rolled condition. These alloys were unidirectionally hot rolled to 80 % reduction at 800 °C and subsequently air cooled. The alloys Ti-8Nb and Ti-12Nb consist of mainly α and α″ phases, respectively and small volume fractions of β phase in hot rolled condition. Both the alloys exhibit non-basal main texture components. The ODF plots display weak, continuous and inhomogeneous [0001]||ND and [001]||ND fibres for the alloys Ti-8Nb and Ti-12Nb, respectively. In plane anisotropy (AIP) and anisotropy index (δ) were calculated from tensile results. Finally, an attempt has been made to correlate in plane anisotropy and yield locus to that of texture present in the hot rolled materials.
Materials Science Forum | 2011
Mithun Palit; J. Arout Chelvane; Himalay Basumatary; S. Banumathy; A. K. Singh; S. Pandian; K. Chattopadhyay
The development of preferred grain orientation has been investigated in the directionally solidified samples of Tb0.3Dy0.7Fe1.95 as a function of pulling speed viz. 10, 40, 70 and 100 cm/h. The study indicates that at lower solidification rate (10 cm/h) growth of and texture components are preferred, whereas, texture component becomes dominant at higher pulling rate (100 cm/h). However, as the solidification progresses, growth of texture component is observed subduing the other components. Consequently, the magnetostriction improves from 1100 to 1350 micro-strains with higher pulling speed.
Materials Science Forum | 2011
M. Premkumar; V.S. Himabindu; S. Banumathy; Amit Bhattacharjee; A. K. Singh
Present work describes the evolution of texture during different modes of deformation by cold rolling of a Gum metal or multifunctional β titanium alloy. The starting and cold rolled materials exhibit the presence of β and β with small amount of stress induced martensitic (α˝) phases, respectively. The development of texture has been explained in terms of α and γ fibres. The bulk hardness appears to be independent of modes of deformation by cold rolling. The yield surfaces of as received and solution treated samples exhibit marked anisotropy which persists during different modes of deformation by rolling.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing | 2012
M. Premkumar; V.S. Himabindu; S. Banumathy; Amit Bhattacharjee; A. K. Singh
Journal of Alloys and Compounds | 2010
S. Banumathy; R.K. Mandal; A. K. Singh
Bulletin of Materials Science | 2011
S. Banumathy; K. S. Prasad; R.K. Mandal; A. K. Singh
Journal of Alloys and Compounds | 2005
S. Banumathy; P. Ghosal; A.K. Singh