Persistent current (PC) operation is important for superconductive magnets used in magnetic resonance imaging (MRI) systems, which demands at least two high critical current joints to form a superconductive circuit. Moreover, the joint resistance and the critical current of the joints always play significant roles in the design and development of large scale applications because the working current and the heat load of the system depend greatly on them. In this work, a joining method using a Mg and B powder mixture as flux is proposed. The voltage-current (V -I ) curves of the sample joints made by such a method were measured using the four-probe method. At 1 T, 4.2 K, the critical current density J c of the best sample was ∼7.19 × 10 4 A cm −2 , and its estimated joint resistance dV /dI was ∼7.44 × 10 −12 . These results demonstrated a promising future for the use of composite MgB 2 tapes in MRI magnets and other large scale superconductive devices.

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