Formation of Fe-Cu-Ni-Sn-VN Nanocrystalline Matrix by Vacuum Hot Pressing for Diamond-Containing Composite. Mechanical and Tribological Properties

The processes of structure formation, mechanical and tribological properties under vacuum hot pressing of a blend of powders of iron, copper, nickel and tin with a dispersion of 5–50 µm with the addition of a nanopowder of vanadium nitride depending on temperature are described. It was found that an increase in sintering temperature from 800 to 1000°C leads to grinding of ferrite grains to 20–400 nm, the release of primary (d = 10–100 nm) and secondary (d ≤ 10 nm) VN grains and an increase in hardness from 3.75 to 5.37 GPa and H/E parameters from 0.021 to 0.043 and H3/E2 from 1.70 to 9.91 MPa, a decrease in the elastic modulus from 176 to 125 GPa and a friction force from 250 to 180 mN, a decrease in speed wear from 8.15 × 10−4 to 1.79 × 10−4 mm3·N−1·m−1. The mechanism of grain refinement and the improvement of physical and mechanical properties is due to α → γ → α transformations occurring under conditions of VN dissolution in α-Fe and subsequent cooling.