The 3-D printing of metal parts promises to revolutionize a wide range of industries. Aircraft carriers, for example, might no longer need to carry spare parts for the myriad aircraft, engines, and weapons systems they carry. Instead, each part could be printed as needed.
The big worry of course is that the mechanical properties of 3-D printed parts might not match those of parts made in other ways, particularly when they are used as critical components, in high-performance jet engines for example.
3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals in particular has found a number of novel applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Whilst many techniques can be used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a resonant microwave cavity 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable to the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared to Al-6061, which has between 0.4 to 0.8%. Our results may pave the way for new possibilities for printing of novel superconducting cavity configurations otherwise impossible to machine as well as the possibility of implementing higher purity powders in the future to improve performance.