The formation of zircon (ZrSiO 4 ) via sintering of milled SiO 2 and ZrO 2 powders was studied, and the effects of slurry vs dry milling, sintering time, and particle size on zircon yield were examined. It was found that very high zircon yields could be obtained via slurry milling, cold pressing, and sintering of the oxide precursors. The controlling factor in determining zircon yield was found to be the particle size of the SiO 2 and ZrO 2 powders. Zircon yield as a function of sintering time was examined, and found to be similar to previous studies in which sol-gel precursors seeded with zircon were used. SEM studies reveal a homogeneous product with particle sizes on the order of 1-5 µm. It was found that complete reaction to zircon can be achieved from a once-through milling, pressing, and sintering process of SiO 2 -ZrO 2 powders.

The most common presenting symptom of aortic dissection is chest pain - headache as the initial manifestation is rare. We report a patient with a history of hypertension who presented with severe bifrontal headache, and was found to have an acute aortic dissection in the absence of carotid artery dissection. A discussion of the atypical presentation and possible pathophysiology follows.

Abstract-An Al-7.5 wt. % Mg alloy was ball-milled in liquid N 2 for eight hours and its microstructures were investigated using transmission electron microscopy. Electron diffraction confirmed that the resulting powder is a supersaturated Al-Mg solid solution with a face-centered cubic structure. Three nanostructures with different grain size ranges and shapes were observed and the deformation mechanisms in these structures were found to be different. The reasons for the different deformation mechanisms were discussed.

The TiN/TiSi2 structure, formed by rapid thermal nitridation of a spatter-deposited titanium film, has been demonstrated to be effective as a diffusion barrier and as a low resistance contact material for VLSI submicron metallization. An optimization experiment, designed using the RS/Discover software package, was used to identify a metallization process that minimized p+ resistance as well as maximized barrier capability. Source/drain implant doses, as-deposited titanium film thickness, and rapid thermal processing parameters were the factors varied in the experiment. Of particular significance is a comparison of the effects of a two-step versus one-step rapid thermal anneal on control of the TiN/TiSi2 thickness ratio. A TiN layer of sufficient thickness for barrier integrity and adequate consumption of implant damage in the formation of the TiSi2 layer are desired. Electrical and thermal stability measuremints of the resultant AlSiCu/TiN/TiSi2 p+ contact system are presented.