3D orientation and strain mapping during hydrogen-based direct reduction of iron oxides

Hydrogen-based direct reduction (HyDR) is an attractive approach to mitigate massive CO2 emissions in the steel industry. During this solid-gas reaction, grain refinement and strain accumulation at the interphase boundaries occurs in solid oxides. Strain build-up leads to cracking and cavitation, which should be controlled. However, the interplay among phase transformation, strain accumulation, and defects formation is still not well understood due to the lack of 3D crystallographic information. Thus, this experiment aims to investigate the 3D orientation and strain distribution in solid oxides during HyDR. Here, we propose to employ interrupted in-situ synchrotron dark-field X-ray microscopy (DFXM) to determine: (i) 3D orientation distribution of a selected hematite grain and its neighboring magnetite grains, and (ii) 3D strain distribution and evolution in selected individual grains of oxides along the reduction process.