| Summary: | In-situ synthesis, microstructure, and mechanical properties of four TiB<sub>2</sub>-Reinforced Fe-Cr-Mn-Al Steel Matrix Composites have been researched in this work. The microstructure and phases of the prepared specimens have been characterized by using scanning electron microscopy (SEM), X-ray diffraction technique, and transmission electron microscopy (TEM). The sintered specimens consisted of Fe<sub>2</sub>AlCr, CrFeB-type boride, and TiB<sub>2</sub>. The mechanical properties, such as hardness and compression strength at room temperature (RT) and at elevated temperatures (600 °C and 800 °C) have been evaluated. The compressive strength and Vickers hardness of the sintered specimens increase with the volume fraction of TiB<sub>2</sub> in the matrix, which are all much higher than those of the ex-situ TiB<sub>2</sub>/Fe-15Cr-20Mn-8Al composites and the reported TiB<sub>2</sub>/Fe-Cr composites with the same volume fraction of TiB<sub>2</sub>. The highest Vickers hardness and compressive strength at room temperature are 1213 ± 35 HV and 3500 ± 20 MPa, respectively. As the testing temperature increases to 600 °C, or even 800 °C, these composites still show relatively high compressive strength. Precipitation strengthening of CrFeB and in-situ synthesis of TiB<sub>2 </sub>as well as nanocrystalline microstructure produced by the combination of mechanical alloying (MA) and spark plasma sintering (SPS) can account for the high Vickers hardness and compressive strength.
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