D C Agrawal
Articles written in Bulletin of Materials Science
Volume 7 Issue 2 July 1985 pp 137-148
The preparation of metallic glass ribbons by melt spinning is a simple technique; however, a researcher often faces many problems when undertaking the preparation of such ribbons. The difficulties encountered are oxidation of the melt, choking of the nozzle by the solidified metal, formation of metal globules or ribbon fragments, oxidation of the ribbons, etc. These problems are particularly severe when working with high melting point alloys. This report describes certain experimental techniques used to overcome problems in preparation of metallic glass ribbons of iron-boron and other high melting point alloys. The ribbons thus produced have been characterized by transmission electron microscopy, mechanical tests and differential thermal analysis. The mechanical strength of the ribbon is comparable to the best recorded strength for ribbons of similar composition. The
Volume 17 Issue 6 November 1994 pp 1005-1014
An RBS study has been carried out to study the relative extent of Pb diffusion in the substrate from PZT films. It is found that extensive diffusion of Pb occurs into the quartz substrate making the film severely deficient in Pb. No such diffusion occurs in the case of PZT films on sapphire and the concentration of Pb is near stoichiometric, except for a small loss due to volatilization. Excessive Pb deficiency, rather than any epitaxial effect, has earlier been proposed by us to be the crucial factor responsible for the existence of the pyrochlore phase in PZT thin films on substrates such as Si, glass, quartz etc. The present results confirm this. The effects of other process variables such as thickness and chemical composition (Zr/Ti ratio) of the film can also be understood in terms of the same phenomenon.
Volume 20 Issue 5 August 1997 pp 685-691
An improvement in fracture toughness and strength is observed in carbon atmosphere sintered alumina on reheating the sintered samples in air at 1200°C. SEM photographs show the presence of secondary precipitate particles at grain boundaries of the sintered samples, which disappear after reheating in air. Infrared spectroscopy indicates that the C-O bond intensity increases on reheating in air. An AES/XPS study reveals that carbon enters the alumina lattice on reheating. These results lead to the conclusion that the enhanced fracture toughness and strength are related to the dissolution of precipitates and consequent dissolution of carbon in alumina lattice.
Volume 21 Issue 1 February 1998 pp 81-86 Research Articles
Powders of tetragonal (
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