Quantitative tomography of pure magnetic-induced effects on metallics during microwave sintering

Directional mass transport phenomena that differ from traditional sintering was found during microwave sintering of NiTi mixed powders, and the underlying magnetic-related mechanisms were analyzed, which benefitted from a newly developed experiment setup that combining a single-model microwave cavity with the synchrotron radiation computed tomography (SR-CT) system. The electric and magnetic fields (H-fields) of microwave can be separated and their direction and amplitude become quantifiable and definitive by using the single-mode microwave cavity, and the microstructure evolution of matter in separate H-field can be online observed by the SR-CT technique. The experimental results showed the presence of special mass transport from Ti particle to Ni particle. It may be caused by different magnetic energy loss in Ni and Ti particles due to their different dielectric properties. The mass transport from Ti to Ni was found to have unequal rates in different directions, which may be caused by the polarization direction of H-field. This study may provide some inspiration for fabricating new metallic materials with oriented microstructure and property by using microwave H-field. It also proves the effectiveness of the single-mode microwave cavity SR-CT experimental setup and provides a new way for in-depth investigation on microwave interaction with matter.