On the mechanochemical activated synthesis of nanocrystalline in-situ Ti(Al)N

This paper reports on our study of the synthesis of titanium nitride solid solution by the reduction of aluminum nitride with titanium by mechanical alloying (MA) using a planetary ball mill. A nanostructure composite of in-situ titanium nitride solid solution was produced through exchange reaction between Ti and AlN. X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe micro analysis (EPMA), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and particle size analysis (PSA) were used to characterize the product. It was found that, with increased milling time, Al resulted from decomposition of aluminum nitride dissolved in the Ti lattice, leading to the formation of Ti(Al) solid solution and a reduction of the Ti lattice interplanar distance. Consequently, the Ti(Al) solid solution reacted with nitrogen to form in-situ Ti(Al)N nano particles. The milled powder had a spheroid shape and a very narrow size distribution of about 1 μm at the end of milling. In-situ Ti(Al)N particles with an average size of 10 nm were attained at a ball-to-powder weight ratio of 10:1 and a Ti:AlN molar ratio of 1:1.

► In-situ Ti(Al)N nanocrystalline particles synthesized by reduction of AlN through a exchange reaction mechanism during MA. ► Determination of the lattice parameters revealed that Ti(Al) solid solution formed during MA. ► With increased MA time, the solid solution reacted with N to form Ti(Al)N nanocrystalline particles.