Large-scale synthesis of dense Fe3C via ultra-high pressure method

In this work, a highly-dense cementite (Fe 3 C) was synthesized via ultra-high pressure method (UHPM). Different raw batches were prepared under identical synthetic conditions (1000 °C and 4.0 GPa for 10 min). Large amounts of Fe 3 C were produced from the raw material consisting of ∼ 6 µm iron powder with ∼ 1.5 µm graphite, illustrating that the particle size and carbon source are critical for synthesizing Fe 3 C via UHPM. The crystal size of the synthesized Fe 3 C was estimated to be approximately 19 nm by peak broadening of the X-ray diffraction pattern. Additionally, the synthesis of Fe 3 C was confirmed by electron probe microanalysis analyzer (EPMA) and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) images showed clearly shaped grain boundaries. The excellent mechanical properties of the prepared Fe 3 C were confirmed based on an ultrasonic pulse reflecting method. According to the magnetic-hysteresis loop of the Fe 3 C, it displayed soft ferromagnetic properties.