Superplastic compressive flow in MgB2

Abstract Macroplasticity in the brittle, superconducting ceramic MgB 2 would allow for the mechanical drawing of thin, dense superconducting wires, as done for metallic superconductors. Here, we report very large uniaxial compressive deformation (engineering strain of 67% or true strain of −1.1) without fracture at 1000 °C for specimens densified from commercially available MgB 2 powders with MgO and MgB 4 second phases. Plastic flow occurs under a diffusion-controlled mechanism with activation energies of 255–447 kJ mol −1 and stress exponents of 1.4–2.0, indicative of superplastic behavior.