Stress and strain effects of Nb3Al conductors subjected to different heat treatments

Uniaxial stress (strain) tolerance was examined for the jelly-roll processed RHQT Nb₃Al multifilamentary wires made by the LTDR, RHQT and TRUQ methods, respectively. There is almost no difference in the stress (strain) tolerance between the three methods, and the degradation of B_c2 under the stress at 500 MPa at t=0.73 and b=0.8 was about 3.2%. The less dependence of the stress (strain) tolerance on the conductor processing suggests that excellent strain tolerance may be an essential advantage of Nb₃Al over Nb₃Sn. The stress dependence of B_c2 in TRUQ method Nb₃Al at 4.2 K was calculated, and the degradation of B_c2 under the stress of 500 MPa was estimated at only 1.5%. Therefore, the high stoichiometry achieved in the Nb₃Al conductors is compatible with greatly improved high-field properties.