Changes to the microestructure during thermal aging treatment at 610 ºC in Fe-xMo-5Ni-0.05C alloys were studied for different aging times with different Mo concentrations. The heat treatment at 610 ºC induces carbide precipitation into the metallic matrix near Fe2Mo phase. The X-ray diffraction studies revealed a more intense precipitation of α-FeMo, Fe3Mo, R(Fe63Mo37) phases and MoC, Fe2MoC carbides for the alloys containing 15 and 11% Mo, respectively. This work shows that hardness and coercive force changes are function of the molybdenum content and aging time variation. Vickers hardness and coercive force both increase with the increase of molybdenum content and reach maximum values at 4 and 1h of aging, respectively.
Fe-Mo-Ni-C alloys; magnetic aging; mechanical aging; magnetic hardness
