7.2.1.5.2.5 Fe-(30-40) wt % Co-Ni-Al-Ti-Cu alloy system

This chapter discusses the properties of Fe-(30···40) wt% Co-Ni-Al-Ti-Cu alloy system. The group of Alnico alloys containing more than 30wt% Co and 5wt% Ti has been developed with the aim of obtaining magnets with higher coercive force. The phase relations and time-temperature transformation curve for (Fe-Co-Ni-Al-Cu)-Ti, Fe-Co-Ni-Al-Cu-Ti-S, Fe-Co-Ni-Al-Cu, Fe-Co-Ni-Al-Cu-C-Ti and (Fe-Co-Ni-Al-Cu)-Ti are illustrated. Mossbauer spectrum for Fe-Co-Ni-Al-Cu-Ti after various heat treatments is shown. Since the phase diagram is rather complex, instead of controlled magnetic cooling, an isothermal heat treatment in a magnetic field MIHT(800,10) is mostly applied in order to obtain optimum magnetic properties. Magnet preparation schemes of Fe-Co-Ni-Al-Cu-Ti are figured out. The dependence of the magnetic properties of equiaxed and columnar samples like Fe-Co-Ni-Al-Cu-Ti-(S + C), Fe-Co-Ni-Al-Cu-Ti-S, Fe-Co-Ni-Al-Cu, Fe-Co-Ni-Al-Cu-Nb and Fe-Co-Ni-Al-Cu-Ti on the chemical composition and measuring temperature are shown. The influence of the various parameters of the preparation technique on the magnetic properties is described in Fe-Co-Ni-Al-Cu-Ti and Fe-Co-Ni-Al-Cu-Ti-S-C.