Structure and phase composition transformation in Cr20Ni80 + Ni₂Al₃ + CrAl₇ layered coating under thermal effect

Abstract

The thermal stability of the Cr20Ni80 / (Ni2A13 + CrAl7) layered coating on Ml copper substrate was studied. It is found, that the sequence of phase transformations in layered coating during the heat treatment in temperature range of 700-1000 °C is Ni2Al3 + CrAl7 → Ni2Al3(Cr) + NiAl(Cr) → NiAl(Cr). It is shown, that an increase in temperature and duration of thermal effect leads to the alignment of Al, Ni and Cr content over the coating thickness due to the diffusion redistribution of elements and to the formation of a secondary reaction zone with a high chromium content.