Ag繊維分散強化Cu合金とその超強磁場発生技術への応用

抄録

Recently, we successfully developed a new Cu-Ag microcomposite alloy with a promising combination of high mechanical strength and high electrical conductivity. When a Cu-16 at% Ag alloy ingot was cold-worked into a wire or a sheet with several times of intermediate annealing at 350-450°C, it shows high conductivity of 75-83% IACS and a high tensile strength of 0.7-1.1GPa at room temperature. These values are superior to those of Cu-Nb microcomposite alloy. The Cu-Ag microcomposite alloy shows excellent mechanical strength with cold work of over 93% areal reduction ratio, while a very heavy cold work of more than 99.97% areal reduction ratio is necessary for realizing such mechanical strength in the Cu-Nb microcomposite. A further advantage of the Cu-Ag microcomposite is easy casting of the alloy ingot, resulting in excellent homogeneity of the microstructure and, therefore, the properties in the alloy wire and sheet. We wound the Cu-Ag microcomposite alloy wire into several pulsed magnets. One of them generated non-destructively 73.4T with duration time of 5msec in a 10mm bore. An other one generated non-destructively 65.3T with duration time of 100msec in a 16mm bore. The feasibility study of the Cu-Ag microcomposite alloy sheet as Bitter magnet sheets is progressing now in collaboration with the Francis Bitter National Magnet Laboratory and the National High Magnetic Field Laboratory. A steady field of 35.2T could be generated by inserting the Cu-Ag microcomposite alloy Bitter sheets into the highest-field region in Hybrid III of FBNML. These pulsed fields and the steady one are world records as of this writing.