Microstructure, mechanical properties and corrosion behavior of an Fe-10Cr-2.7B-5.5Al-13Mn alloy prepared by spark plasma sintering

An Fe-10Cr-2.7B-5.5Al-13Mn alloy has been fabricated by the combination of mechanical alloying (MA) and spark plasma sintering (SPS). Microstructure and phase evolution of the alloy powder and sintered specimen were investigated by using scanning electron microscopy (SEM), X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The resultant mechanical properties were determined in Rockwell hardness and compressive strength. The corrosion behavior was tested by investigated test in 750 °C molten pure aluminum for 1 h and 4 h. Results have shown that the sintered specimen is mainly composed of Fe2AlCr intermetallic, CrFeB-type boride and Mn2B-type boride uniformly distributed in the γ matrix. The sintered specimen achieves Rockwell Hardness and compressive strength of 59.7 ± 0.2 HRC and 2823 ± 21.0 MPa at room temperature, respectively. Especially, compressive strength of the sintered specimen at 600 °C reaches 902 ± 15.5 MPa. The high hardness and compressive strength can be attributed to solid solution of Al, Cr and Mn, precipitation of CrFeB, Mn2B and Fe2AlCr in the γ-Fe matrix and nanocrystalline microstructure produced by the combine of MA and SPS. The corrosion rate of the sintered Fe-10Cr-2.7B-5.5Al-13Mn in molten aluminum is ～ 36% of that of H13. CrFeB, Mn2B and Fe2AlCr play a key role in improving the corrosion resistance of the sintered specimen in molten aluminum. They are embedded in the corrosion products (intermetallics) and act as roots to capture the intermetallics from falling off.