Magnetic properties of nanocrystalline Ni3Fe compacts prepared by spark plasma sintering

Nanocrystalline Ni3Fe compacts were successfully prepared by spark plasma sintering starting from wet mechanically alloyed powders. The influences of the sintering conditions: sintering temperature, sintering time and particle size on the compact magnetic properties are investigated. It is found that high sintering temperature, increased sintering duration and larger particle size leads to compacts with improved soft magnetic properties. A contamination with carbon of the compacts during the sintering processes has been found to reduce their magnetic properties. It is found that a heat treatment at the temperature of 450 °C during 4 h, in hydrogen atmosphere, leads to an improvement of the compact coercivity and of the maximum relative permeability of the compact to up to 600% and 50% respectively. Spark plasma sintering can consequently be considered as promising compaction technique for processing Ni3Fe nanocrystalline powder in particular and nanocrystalline soft magnetic alloys in general. [Display omitted] ► Nanocrystalline Ni3Fe compacts successfully obtained by spark plasma sintering. ► Magnetic properties explained by compacts density and initial recrystallization. ► A decarburizing heat treatment leads to improving soft magnetic properties. ► A protocol to obtain magnetic compacts from nanocrystalline powder was proposed.