Formation mechanisms and atomic configurations of nitride phases at the interface of aluminum nitride and titanium

Abstract

Aluminum nitride was bonded with a titanium foil at 1400 degrees C for up to 1 h in Ar. The AlN/Ti interfacial reactions were investigated using analytical electron microscopy. Reaction layers, consisting of delta-TiN, tau(2)-Ti2AlN, gamma-TiAl, alpha(2)-Ti3Al, a two-phase region (alpha(2)-Ti3Al + alpha-Ti), and alpha-Ti (Al, N) solid solution, were observed after annealing at 1400 degrees C for 0.1 h. Among these phases, the alpha(2)-Ti3Al and (alpha(2)-Ti3Al + alpha-Ti) were formed during cooling. Further diffusion of N atoms into the reaction zone precipitates a chopped fiber-like alpha(2)-Ti2AlN in the matrix of gamma-TiAl, with [110](gamma-TiAl)//[11 (2) over bar0](tau 2-Ti2AlN) and (1 (1) over bar(1) over bar)(gamma-TiAl)//(1 (1) over bar0 (3) over bar)(tau 2-Ti2AlN), by substituting N atoms for one-half Al atoms after annealing at 1400 degrees C for 1 h. The released Al atoms, due to the precipitation Of tau(2)-Ti2AlN, resulted in an ordered Al-rich gamma-TiAl or Ti3Al5. Furthermore, the alpha-Ti (Al, N) was nitridized into a lamellar layer (delta-TiN + alpha-Ti) with [110](delta-TiN)//[11 (2) over bar0](alpha-Ti) and (111)(delta-TiN)//(0001)(alpha-Ti).