Heat treatment, magnetic and mechanical properties of sintered isotropic Fe-32Cr-22Co alloy with various alloying elements

Alloying components have been actively used to improve properties of Fe-Cr-Co hard magnetic alloys. However, in most cases researchers have been used multiple components simultaneously and rarely compared obtained properties with those of the base ternary Fe-Cr-Co alloys. As a result, it is quite difficult to determine the individual contribution of each alloying component into modification of the alloy properties. In this paper individual effects of following alloying components: Mo, Nb, Si, Ti, V, W, on heat treatment and properties of the Fe-32Cr-22Co (wt.%) alloy have been studied. Alloys were obtained using powder metallurgy method, including charge pressing and vacuum sintering. It has been demonstrated that Mo, Si and W increase coercive force and maximum energy product of the ternary Fe-32Cr-22Co alloy up to 57.1 – 63.6 kA / m and 17.1–19.3 kJ / m3, respectively. On the other hand silicon doping significantly changes heat treatment conditions by shifting optimal isothermal holding temperature 20 – 25°C lower compared to other alloys and also leads to formation of non-magnetic σ-phase at 640°C, which is greatly reduce the magnetic properties. It has been noted, that most of the alloying elements, which are partially transited into oxide phase, are not increasing the magnetic properties. It has been demonstrated, that Nb significantly increases the yield strength of the Fe-32Cr-22Co alloy to 2000 MPa. It has been shown, that most of alloying additives with the exception of Ti reduce the ductility of the Fe-32Cr-22Co ternary alloy; fracture strain of most samples was 8 – 9.5 %.

1. Russian Science Foundation - 24-29-00323