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

Hot-dip aluminizing and interdiffusion treatment were used to develop TiAl3-rich coatings on a Ti3Al–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 Al2O3-rich scales during the high-temperature oxidation. A layered structure of Al2O3/TiAl3/(TiAl3 + TiAl2)/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 Al2O3/TiAl3/(TiAl3 + TiAl2)/(TiAl2 + TiAl3)/TiAl/alloy.

► TiAl3-rich coatings have been prepared on a Ti3Al–Nb alloy by hot-dip aluminizing.
► The coatings can be modified by addition of element Si, Mn, or Ag.
► The modified coatings show better thickness uniformity and fewer cracks.
► The coatings form protective Al2O3-rich scales during high-temperature oxidation.