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金沢大学大学院自然科学研究科機能創成システム, The effects of addition of Zr and Ag on the mechanical properties of a Cu-0.5 wt%Cr alloy have been investigated. The addition of 0.15 wt%Zr enhances the strength and resistance to stress relaxation of the Cu-Cr alloy. The increase in strength is caused by both the decrease in inter-precipitate spacing of Cr precipitates and the precipitation of Cu5Zr phase. The stress relaxation resistance is improved by the preferentially forming Cu5Zr precipitates on dislocations, in addition to Cr precipitates on dislocations. The addition of 0.1 wt%Ag to the Cu-Cr and Cu-Cr-Zr alloys improves the strength, stress relaxation resistance and bend formability of these alloys. The increase in strength and stress relaxation resistance is ascribed to the decrease in inter-precipitate spacing of Cr precipitates and the suppression of recovery during aging, and to the Ag-atom-drag effect on dislocation motion. The better bend formability of the Ag-added alloys is explained in terms of the larger post-uniform elongation of the alloys. © 2007 Springer Science+Business Media, LLC.

The laboratory development of sol/gel ceramic fibres requires rapid objective means of assessing the mechanical and thermal properties of a product at the earliest stages of preparation. The merits of a simple tumbling test, leading to a fibre friability index, and the Bend Stress Relaxation test, which gives a high temperature creep rating, are demonstrated on commercial Saffil and Safimax alumina fibres and a development Saffil zirconia fibre, each in staple blanket form. Measurements on Altex continuous alumina/silica fibre and Nicalon are also presented. Standard and off specification alumina fibres are readily distinguished by their friability indices which correlate with the fibre strain to break. Saffil and Safimax alumina are comparable to Nicalonin terms of creep and superior to Altex. Saffil zirconia approaches alumina creep performance after post firing to 1250°C.