Study of the Heat Treatment Profiles Applied to a Multifilamentary MgB2 Superconducting Wire

MgB2 is a strategic material for practical application, due to the high values of its superconducting parameters. Cables, wires, and tapes can be produced making use of the MgB2 superconductor. For wires, long lengths and homogeneity are necessary for the applicability of this material. The heat treatment is one of the most important steps to homogenize the MgB2 along the entire length. In preview works we developed a multifilamentary superconducting wire with addition of AlB2-type impurities and a simultaneous carbon source. The final wire is composed of 42 MgB2 -filaments with average diameter of 200 mu m and a diffusion barrier with thickness around 50 mu m. Due to the low dimension of its parameters, a specific heat treatment profile is required. In the present work we present detailed study of the heat treatment profiles used for MgB2 superconducting wires around the world and applied these concepts to our multifilamentary wire, in an attempt to optimize the microstructural characteristics. Several different profiles of heat treatment were applied for this wire, and some characterizations were performed to analyze the influence of the heat treatment on the microstructural properties. As a result, the methodologies were satisfactory, presenting good options of heat treatment for superconducting wires with micrometer-size filaments.