Soft magnetic Cu–Co–Ni composite materials produced by mechanical alloying, cold compaction and sintering

Abstract

Cu 90 Co 10 and Cu 85 Co 10 Ni 5 soft magnetic alloys were obtained by non-equilibrium phase synthesis. Elemental powder mixtures were mechanically alloyed in a planetary mill to disperse ultrafine Co and (Co,Ni) particles in the copper matrix. Thus, it was possible to modified magnetic properties of these materials. Resulting powders were characterised as a function of milling time by means of X-ray diffraction, SEM, high resolution transmission electron microscopy and electron probe microanalysis. The variation of magnetic properties and its dependence on the structure/ precipitation change with milling time for each alloy are discussed. Magnetic properties of Cu-Co and Cu-Co-Ni powders reached their optimum values after milling for 60 h. On the other hand, superparamagnetic behaviour was observed at 300 K in the Cu-Co-Ni alloys. Both alloys were consolidated after 60 h milling by cold compaction and sintering at 973 K for 1 h. Although this treatment is performed at high temperature, precipitation and coalescence of Co particles on the Ni 5 Co X Cu 952X system was retarded by the presence of Ni in solid solution in Cu matrix.

Microstructure and magnetic properties of Cu90−xCo10Nix–7.5% SmCo5 composite alloys prepared by mechanical alloying and hot pressing

“…It was measured that the physical and mechanical properties of dispersion-strengthened copper alloys are directly related with microstructural features, such as particle volume fraction, size, stability and solubility of these particles in the copper matrix. In addition to very good mechanical properties within a wide range of temperatures, other interesting engineering properties, such as optical, electrical, thermal and magnetic, have been also improved because of the outstanding properties of nanomaterials [13][14][15][16][17][18][19][20][21][22].…”

“…This processing route (mechanical alloying/milling and subsequent annealing) presents a double advantage: (i) control the spatial Co particle arrangement in the copper matrix and (ii) diminution of the internal stresses. In order to improve the magnetic properties in Cu–Co alloys, the addition of elements, such as Cr, Fe and Ni [13,14,22,15,16] has been tried. Among these elements, only Ni gives a prospect with an improved GMR.…”

The effects of mechanical milling on the structural, mechanical, and electromagnetic properties of Cu-8 wt% NdFeB composite alloys

“…6–9 In an attempt to develop new copper composite materials with optimal balance between structural (mechanical) and functional (electrical or magnetic) properties, special attention has been paid to reinforce a copper matrix by MA with functionalized multiwall carbon nanotubes 10 or ferromagnetic or superparamagnetic nanoparticles of Co, SmCo5, and Nb3Sn. 11–13 Since one of the main challenges inherent to MA is to obtain a homogeneous distribution of reinforcement particles in the matrix, 14–16 process parameters were carefully controlled and optimized in these works.…”

Magnetic and structural properties of hot pressed Cu–SmCo5composites obtained by mechanical alloying

“…Recently, we have investigated the magnetic behaviour of copper alloys and studied the effect of milling time and consolidation process on the structural, mechanical, electrical and magnetic properties induced by magnetic cobalt cluster of nanometric size precipitation in Cu-Co and Cu-Co-Ni alloys prepared by mechanical alloying. 8,9 In view of investigating novel industrial applications of copper composite materials, we aimed to synthesise and characterise novel copper intermetallic (Cu-8 wt%SmCo 5 ) composite alloys by mechanical milling and establishing the relationship between structural, mechanical and functional (electrical and magnetic) behaviours applicable to advanced electromagnetic devices. SmCo 5 is a well known compound that exhibits extremely high magnetocrystalline anisotropy and suitable for permanent magnet applications.…”

“…Among them are alloys that exhibit great variations in electrical resistivity when the magnetic field is applied, known as giant magnetoresistance, which varies with the content of precipitated or dispersed magnetic particles in a metastable copper solid solution. Recently, we have investigated the magnetic behaviour of copper alloys and studied the effect of milling time and consolidation process on the structural, mechanical, electrical and magnetic properties induced by magnetic cobalt cluster of nanometric size precipitation in Cu–Co and Cu–Co–Ni alloys prepared by mechanical alloying 8,9…”