ANOMALOUS STRAIN-RATE SENSITIVITY OF FLOW-STRESS IN SUPERCONDUCTING AL AND AL-MG ALLOYS

An anomalous strain-rate sensitivity of yield stress in superconducting Al and Al Mg alloys has been found experimentally. It is discussed that this phenomenon is due to an anomalous increase of the yield stress τs in the superconducting state, induced by the destruction of the Cooper pairs by dislocations. The result agrees well with the calculation by Huffman and Louat. Δτsn = τn - τs, where τn is the yield stress in the normal state, and the above-mentioned strain-rate sensitivity of Δτsn are hardly explained by classical theories of the strength of metals and alloys. A new theory of the strength of solid-solution alloys has been worked out. On this basis, Δτsn and its strain-rate dependence are analytically expressed and compared successfully with experiment. © 1979.