High-temperature oxidation of hot-dip aluminizing coatings on a Ti3Al–Nb alloy and the effects of element additions

Abstract Hot-dip aluminizing and interdiffusion treatment were used to develop TiAl 3 -rich coatings on a Ti 3 Al–Nb alloy. The addition of Si, Mn, or Ag to the coatings improves the thickness uniformity and reduces the formation of the through-thickness transverse cracks. The element additions promote the formation of dense and continuous Al 2 O 3 -rich scales during the high-temperature oxidation. A layered structure of Al 2 O 3 /TiAl 3 /(TiAl 3 + TiAl 2 )/TiAl/Ti-depleted alloy/alloy from the outside to the inside forms after oxidation at 900 °C without changing the main body of the Si- or Mn-modified coating, and the Ag-modified coating develops a layered structure of Al 2 O 3 /TiAl 3 /(TiAl 3 + TiAl 2 )/(TiAl 2 + TiAl 3 )/TiAl/alloy.