Effect of Gas Atmosphere in Aluminobarothermal Synthesis on the Structure of Metal Matrix Composites Based on Fe – Cr – Mn – Mo Alloy

The structures of metal matrix composites based on the Fe – Cr – Mn – Mo system and fabricated by an aluminobarothermal process with the use of argon or nitrogen as the gas atmosphere in the reactor are compared. Chemical analysis for the content of the metals, nitrogen and oxygen in the samples is performed. The structure is studied in different conditions. The total hardness of the samples and the microhardness of their matrixes are determined. It is shown that the morphology of the reinforcing nonmetallic particles depends on the type of the gas atmosphere in the reactor during the synthesis and remains unchanged after a 2-h hold at 1250°C and water cooling. The determined coefficients of recovery of nitrogen from the nitrided chromium and the data of the diffraction analysis are used to show that the aluminobarothermal synthesis under nitrogen pressure is an optimum variant.