NiAl Deposit Produced by PTA Surfacing Process and Its Oxidation Behavior

Plasma transferred arc (PTA) surfacing process was proposed to produce in-situ intermetallic compound (IMC) surface layers. This process was quite capable of producing NiAl intermetallic composite surface layers on mild steel with physically mixed powder of nickel and aluminum. In the surface layer, the equiaxed and columnar structure of which grain size was 100-150 μm range were formed. The surface deposit was identified as NiAl and Fe3Al by a XRD analysis. The oxidation behavior of the surface deposits has been studied in air with isothermal conditions at 1173-1373 K up to 432 ks. The surface deposit with lower iron contents showed the formation of thin and uniform oxide film, whereas the surface deposit with higher iron contents showed coarse oxide film.