Exceptional superconducting properties in laser powder bed fusion Nb47Ti superconductors employing heat treatment post-processes

<p dir="ltr">This study optimises heat treatment and aging to enhance the superconducting properties of in-situ alloyed Nb47Ti superconductors produced via laser powder bed fusion (LPBF). Under optimal conditions, the alloy achieves a high density (6.11 g/cm³) and minimal Nb segregation (0.05 %). Solution treatment at 1250 °C for up to 24 h improves Nb dissolution, creating a homogeneous β-NbTi matrix. Aging at 425–500 °C for 72–120 h enhances superconductivity by precipitating α-Ti. While all samples exhibited a critical transition temperature of around 9 K, the highest critical current density (<i>J</i>_<em>c</em>) of 14.6 kA/mm² at 4.2 K and 5 T was achieved by aging at 450 °C for 120 h, reaching 81 % of the theoretical limit for NbTi superconductors. This improvement is attributed to nano ω-Ti phase formation during the solution treatment, which transforms into α-Ti pinning centres. The optimised process also enhances mechanical properties, with the best-aged sample reaching 450 HV0.5 microhardness. These findings demonstrate the potential of LPBF combined with tailored heat treatments to produce NbTi superconductors with exceptional Jc and mechanical strength, providing a superior alternative to conventional manufacturing.</p>