Characterization of $Ni_3Al$ and $Ti_3Al$ Coatings Produced by Electric Current Activated Sintering Method

The present study reports on $Ni_3Al$ and $Ti_3Al$-based intermetallics coated on AISI 1010 steel substrate by one-step pressure assisted electric current activated sintering method. Ni, Ti, and Al elemental powders were mixed in the stoichiometric ratio corresponding to the $Ni_3Al$ and $Ti_3Al$ intermetallics at molar proportion of 3:1. The mixed coating powders were placed onto the steel substrate in a mold, and pressed with compressive stress of 100 MPa and then, electric current: 1100-1200 A, voltage 2.9-3.4 V was applied for 15 min during coating. As-synthesized coatings seem to have good adherence with many small porosities. The phases formed in the $Ni_3Al$ coating layer were $Ni_3Al$ as a major phase beside NiO and $NiAl_2O_4$ trace phases, which were confirmed by X-ray diffraction analysis. However, TiAl and Ti trace phases besides major $Ti_3Al$ phase were detected in the $Ti_3Al$ coating. The hardness of the $Ni_3Al$, $Ti_3Al$ coatings and AISI 1010 substrate was approximately 321 ± 18, 445 ± 13 and 157 $HV_{0.5}$, respectively.