Superplastic compressive flow in MgB₂

Macroplasticity in the brittle, superconducting ceramic MgB₂ 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 MgB₂ powders with MgO and MgB₄ 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.