Effect of compositions on the microstructure and properties of plasma clad NiAl coating

NiAl intermetallic coating was in-situ synthesized by the plasma cladding process. The effect of atomic ratio of Ni to Al atoms 1 (coating 1), 2 (coating 2) and 3 (coating 3) on the microstructure and mechanical properties of plasma clad was studied by combining microstructural analysis and wear-resistant test. The obtained results indicated that the microstructure of the synthesized NiAl coating was compact and uniform in addition to few porosities and the NiAl coating well metallurgically bonded with the substrate. Coating 1 is mainly composed of NiAl and the solid solution γ-(Fe,Ni) phases. Coating 2 contains of NiAl, Ni3Al and γ-(Fe,Ni). Coating 3 is mainly composed of Ni3Al, γ-(Fe,Ni) and NiAl. Coating 3 has excellent wear-resistance property owing to high hardness and low friction coefficient. Ni3Al phase has great influence on wear-resistance property of coating 3. The main wear mechanism of coating 1 is multi-plastic deformation wear and adhesion wear. Grain abrasion is the main wear mechanism of coating 3. The main wear mechanism of coating 2 is grain abrasion and partly adhesive wear.