Magnetic and structural properties of hot pressed Cu–SmCo 5 composites obtained by mechanical alloying

Abstract

Cu–8 wt-%SmCo₅ alloys were obtained through mechanical milling for novel industrial applications. Copper and SmCo₅ powder mixtures were mechanically alloyed in a planetary ball mill to disperse SmCo₅ fine particles in the copper matrix with the aim to modify the structural, mechanical, electrical and magnetic properties. The resulting alloyed powders were characterised as a function of milling time. Under the magnetic field, SmCo₅ particles achieved M_s to improve the soft magnetic properties of copper–8 wt-%SmCo₅ to be used in dielectromagnetic components. The magnetic properties of Cu–8 wt-%SmCo₅ powders reached their optimum values after milling time ranging from 10 to 15 h. The consolidation of milled alloy powders was performed by uniaxial hot pressing at 923 K for 2 h under argon atmosphere to obtain dense compacts. The consolidation process resulted in good dense metal matrix composite materials with adequate properties of compression strength >900 MPa, 95 HRB in hardness, electrical conductivity up to 43% of that of the International Annealed Copper Standard (IACS) and magnetic properties such as coercive field, saturation and remanent magnetisation obtained at 218 Oe, 70·23 emu g⁻¹ and 6·09 emu g⁻¹ respectively at 300 K. The existence of a coercive field and a little magnetic memory of the consolidated system is a typical behaviour of magnetically soft materials. The variation of electric and magnetic properties and its dependence on structure strength change with milling time were discussed.