Influence of Annealing on the Structural-Phase State and Properties of Gas-Thermal Al-Fe-Cr-Ni Pseudoalloy Coating Obtained by the Method of High-Speed Spraying of Wire Materials

Abstract

The structural-phase state and durometric properties of gas-thermal Al-Fe-Cr-Ni pseudoalloy coatings have been studied. It is found that the sprayed coating is characterized by low porosity (up to 5 vol.%), low content of the austenite phase and iron and aluminum oxides. It is shown that the pseudoalloy hardness is HV10, and its microhardness is 450 HV0.025. The subsequent annealing of the composite coating in the temperature range of 350–550 °С leads to the precipitation of a large amount of strong intermetallic phases Fe13Al4 and Al5Fe2 in it. At the same time, the maximum hardness (220–230 HV10) of the Al-Fe-Cr-Ni coatings is recorded after annealing at 450 and 500 °C for 3–4 h, the maximum microhardness values (580–620 HV0.025) — after annealing at 500 and 550 °C for 2 h. Long-term exposure of coatings at elevated temperatures (500 and 550 °C) leads to a significant increase in their porosity (up to 20–50 vol.%).

Keywords

• pseudoalloy
• annealing
• structural-phase state
• porosity
• durometric properties