Stability of Oxides in Metal or Metal Alloy Matrices.
Abstract
The objective of the research discussed was to conduct a study of the chemical interaction between Tyco single-crystal sapphire filaments and nickel and nickel alloys, and of the effect of these interactions on filament strength. Studies were performed as a function of time at various temperatures between 1100C and 1350C, and in both oxidizing and reducing atmospheres. Pure nickel and two alloy matrices were studied: nickel-chromium alloy (21.5%-18.5%), and Udimet-700. The surface of the Tyco sapphire filaments was found to be relatively smooth on a macro scale, although voids were present below the surface. However, after contact with nickel in an inert or reducing atmosphere, the surface was found to be pitted, and the filament strength was reduced. In an air atmosphere, nickel spinel was formed at the filament/metal interface. In a nichrome matrix the presence of chromium decreased the extent and severity of reaction in both hydrogen and air. For Udimet-700 matrices, all hot pressing conditions resulted in severe rod breakage. In an experiment in which sapphire rods were imbedded in liquid Udimet-700, the thermal compressive stresses generated during cooling were sufficiently large to cause slip and severe rod breakage. It was found that titanium had concentrated preferentially at the interface region during hot pressing. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1970
- Accession Number
- AD0872893
Entities
People
- Richard L. Mehan
Organizations
- General Electric