Eihachiro Tanaka

TRANSITION TEMPERATURES OF LAMINATED INTERMETALLIC COMPOUNDS Nb3Sn AND Nb3Al0.8Ge0.2

In the present report, data are presented on the transition temperatures and the critical currents of laminated Nb3Sn and Nb3Al0.8Ge0.2 tapes. The samples were prepared by rolling techniques and diffusion process. At first, the plates were prepared by accumulating foils of materials alternatively. Then the plates were rolled to a flexible tape and heat‐treated. By heat treatment the transition temperature Tc of Nb3Sn tape increases and reaches the constant value ≃ 18.0°K for 10 min at 1050°C. For Nb3Al0.8Ge0.2, Tc = 19.2°K is obtained by heat treatment at 1600°C for 1 min and annealing at 760°C for 2 h. The critical currents of the samples are discussed.

On the Embrittlement and Toughness of High Purity Fe-30Cr-2Mo Alloy

Experiments were conducted to explain unexpected embrittlement phenomena encountered in fabricating a high-purity Fe-30Cr-2Mo alloy. By means of a hydrostatic tension test with a Bridgman-type specimen it was found that the fracture behavior of the alloy is highly dependent on stress state. Under conditions of low triaxial stress, the alloy displays excellent ductility. Under conditions of high triaxial stress, however, it shows less strain to fracture and a transition from ductile to cleavage fracture. The toughness of the Fe-30Cr-2Mo alloy can be significantly improved by thermomechanical processing.