Microstructural transformation during combustion synthesis of MgB2 superconductor

To investigate the phase transformation behaviors of combustion synthesis of MgB2, a mixture of Mg, B was used for a combustion front quenching test, and the microstructural evolution in the quenched sample was observed by scanning electron microscopy (SEM) and electron probe microanalyzer (EPMA). The temperature–time profile of the combustion was measured, and the phase constituents of the different zones of the quenched sample were inspected by X-ray diffraction (XRD). Based on these experimental results, the transformation behaviors in the SHS-synthesized superconductor MgB2 was analyzed, and a solid phase diffusion and dissolution–precipitation mechanism was proposed.