Abstract: High temperature melting niobium-titanium-chromium-aluminum-silicon alloys having a wide range of desirable microstructures, excellent microstructural and morphological properties, superior oxidation resistance at temperatures from 1000.degree. C. to 1500.degree. C., and good low temperature toughness and good high temperature strength and creep resistance are described which comprise generally two- or three-or four-phase alloys systems having compositions (31-41)Nb-(26-34)Ti-(8-10)Cr-(6-12)Al-(9-18)Si. Two-phase beta+Nb.sub.5 Si.sub.3 -base alloys can be obtained by increasing the Nb/Ti ratio, while three-phase beta+Nb.sub.5 Si.sub.3 -base+Ti.sub.5 Si.sub.3 -base alloys or four-phase beta+Nb.sub.5 Si.sub.3 -base+Ti.sub.5 Si.sub.3 -base +Ti.sub.3 Si-base alloys can be obtained by decreasing the Nb/Ti ratio.

Abstract: High temperature melting molybdenum-chromium-silicon alloys having good high temperature strength and specific stiffness are described which comprise Mo--Cr--Si alloys in the Mo-rich (Mo, Cr)--(Mo, Cr).sub.3 Si two-phase field.

Abstract: High temperature melting molybdenum-chromium-silicon alloys having good high temperature strength and specific stiffness are described which comprise Mo--Cr--Si alloys in the Mo-rich (Mo, Cr)--(Mo, Cr).sub.3 Si two-phase field.

Abstract: Disclosed is a method for making polyorganosiloxane networks (preferably polydimethylsiloxane) with controlled heterogeneity of the molecular weight between crosslinks. Low molecular weight functionally terminated polyorganosiloxanes are reacted with a polyfunctional crosslinking agent to form a product of molecular weight from about 1.33 to 15 times that of the starting materials. These partially crosslinked chains are then reacted with more crosslinking agents and functionally terminated polyorganosiloxanes of 20-40 times higher molecular weight. The molecular weight achieved In the first reaction has an effect on properties such as modulus, birefringence, and stress optical coefficient. The low molecular weight chains in this form serve to increase modulus and durability while keeping optical clarity of the inherently soft networks.