A study on the microstructure and property development of d.c. magnetron co-sputtered ternary titanium aluminium nitride coatings Part II Effect of magnetron discharge power

Abstract

Advanced ternary (Ti,Al)N coatings were produced by reactive magnetron co-sputtering technique with separate titanium and aluminium targets at a 30° magnetron configuration. The aluminium magnetron discharge power was adjusted from 0 to 6.0 W/cm² to investigate the effect of magnetron discharge power on the microstructure and property development of the coatings. It was found that increasing the aluminium magnetron discharge power caused the deposition rate and the aluminium content to increase, and the grain size and surface roughness of the coatings to decrease substantially. Tighter packing of the grain columns occurred and the microstructure changed from a porous zone 1 to a densified zone T structure, resulting in a continuous increase of the coating hardness. The major texture component of the coatings changed from the (111) to (200) orientations. The (101) orientations of the AlN structure also developed. It was found that the microstructure and hardness enhancement of the coatings was associated with an increased formation of the TiAlN and AlN phases and a densified, fine grain structure at higher magnetron discharge powers.