Abstract
Iron aluminides based on Fe3Al were produced by extrusion of gas atomised powders. The influence of alloying additions such as Cr, Mo, Nb, Zr, Ti, Si, Mn, and B was studied in order to improve the ductility at room temperature and mechanical strength at elevated temperatures with other properties retained or improved. Examinations were made on extruded material in the as extruded as well as the heat treated condition. Heat treatments were performed in the temperature range 500–850°C. Microstructural studies show a strong extrusion texture and that most of the alloys recrystallise below 750°C. Alloying additions affect the ordering transformation (D03 to B 2) temperature, which has been studied by differential scanning calorimetry. Transformation temperatures from approximately 550°C to 650°C have been obtained. Hot hardness was investigated up to 700°C. At room temperature the hardness values for the different alloys are in the range 280—420 HVO·5. At 300°C the hardness values are in the range 210—330 HVO·5; at 500°C they are 170—250 HVO·5; and at 700°C they are 40—80 HVO·5. Tensile tests were performed in the as extruded condition in air at room temperature and at 600°C. At room temperature the elongation at fracture is in the range 5—10%; 0·2% proof strength R p0·2 470—840 MN m−2; and tensile strength 880—1330 MN m−2. At 600°C R p0·2 varies between 440 and 590 MN m−2 with corresponding fracture elongations of 20–60%. PM/0700
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