Structural features of a composite material produced by electric pulsed pressing from iron‑based multi‑component powder mixtures

Abstract

The study is dedicated to the electric pulse pressing use for the composite materials production from diffusion‑alloyed iron powders. It is shown that the addition of a low–melting metal component, tin, has a positive effect on the compaction of the composite iron powder during electric pulse pressing. The density of samples from Dystaloy AB iron powder with the addition of 10 % tin reaches 7.3–7.5 g/cm3. It is impossible to obtain such a density in the conventional cold pressing process at a pressure of 100– 120 MPa. It is established that due to the short duration of thermal exposure during electric pulse pressing, diffusion processes do not have time to pass and the distribution of alloying elements in the iron base is uneven. A short thermal exposure causes oxidation of the surface of the powder particles, which also negatively affects the diffusion processes. Therefore, when obtaining alloyed powder materials by electric pulse pressing, the process must be carried out in a protective atmosphere. The revealed presence of a nanoscale substructure formed due to the effects of intense plastic deformation and temperature indicates the hardening of the powder composite material during electric pulse pressing. These features can be useful in the development of technologies alternative to the warm pressing of plasticized powders.