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.