Evolution of the microstructure of Cu–Fe–Co–Ni powder mixtures upon mechanical alloying

• Nanocrystalline (10–30 nm) metastable phase on the base of Cu–Ni solid solution was formed.
• hBN prevents formation of metastable phase on the base of Cu–Ni solid solution under mechanical alloying.
• Addition of hBN particles into Cu–Fe–Co–Ni matrix without MA increases the bending strength and hardness.

Nanocrystalline Cu–Fe–Co–Ni and [Cu–Fe–Co–Ni]-hBN powders composed of segregated particles and with lamellar and homogeneous structure were obtained by means of mechanical alloying. The powders were milled in planetary centrifugal mill and characterized by SEM, EDS, XRD, TEM and HRTEM. The results of investigation indicate that processing leads to formation of single-phase product with fcc lattice — Cu-Ni-based solid solution. Addition of hBN into mixture results in deceleration of fcc solid solution forming and improving of mechanical properties. The hot-pressed samples made of mechanically alloyed at long duration Cu–Fe–Co–Ni and [Cu–Fe–Co–Ni]-hBN powders exhibit low strength due to high volume of nanopores. Mixing in ball mills preventing the occurrence of mechanical alloying is recommended to be used to fabricate binders for diamond- and cubic boron nitride cutting tools.

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