Glass formation, density, microhardness, and microstructure of the As-Se-Tl chalcogenide alloys

The As-Se-Tl chalcogenide glasses are an important class of IR transmitting glasses, and are used as the braze materials in the optical systems. To understand the basics of the As-Se-Tl alloys, measurements were made on the glass formation region, density, microhardness and microstructure of alloys with compositions ranging from 5 wt% As to 50 wt% As. The glass formation region is determined based on powder X-ray diffraction analysis. The densities, experimentally determined by using the Archimedean theory. ranged from 4.46 g cm(-3) to 7.00 g cm(-3), and were less than those calculated by using the mixing rule. The Vickers hardness analyzed by using a microhardness tester ranged from 58 to 126 as the composition changed from As-80 wt% Se-15 wt% T1 to As-50 wt% Se-10 wt% Tl. Miscibility-gap-like microstructures were observed in some of the As-Se-Tl alloys. (C) 1997 Elsevier Science B.V.