TY - JOUR
T1 - Evolution of the fracture properties of arc evaporated Ti1-xAlxN coatings with increasing Al content
AU - Waldl, Helene
AU - Tkadletz, Michael
AU - Lechner, Alexandra
AU - Czettl, Christoph
AU - Pohler, Markus
AU - Schalk, Nina
PY - 2022/7/16
Y1 - 2022/7/16
N2 - Although the positive effect of an increasing Al content in Ti1-xAlxN hard coatings within the cubic regime is thoroughly investigated, there is a lack of systematic studies on the fracture properties. Thus within the present work, seven Ti1-xAlxN coatings with increasing Al content from x = 0 up to x = 0.78 were deposited by cathodic arc evaporation. Using scanning electron microscopy and X-ray diffraction, a grain refinement with increasing Al content up to x = 0.65 could be observed, while the coating with the highest Al content of x = 0.78 showed again a coarser grain size. The presence of a single phase face-centered cubic (fcc)-structure up to an Al content of x = 0.49 was confirmed by X-ray diffraction. Ti0.44Al0.56N and Ti0.35Al0.65N exhibited a dual phase fcc- and wurtzitic (w)-structure, where for the latter the w-structure is dominating. A single phase w-structure was observed for the Ti0.22Al0.78N coating. Nano-indentation experiments revealed an increasing hardness with increasing Al content up to x = 0.56 and thus, as long as the fcc-phase is dominating, due to decreasing grain size and increasing compressive stress. For the coatings with dominating and pure w-structure a drop in hardness was observed. Similar to the hardness, the micromechanical bending tests also revealed improving fracture properties with increasing Al content up to x = 0.56 and deteriorating fracture properties when the w-structure becomes dominant.
AB - Although the positive effect of an increasing Al content in Ti1-xAlxN hard coatings within the cubic regime is thoroughly investigated, there is a lack of systematic studies on the fracture properties. Thus within the present work, seven Ti1-xAlxN coatings with increasing Al content from x = 0 up to x = 0.78 were deposited by cathodic arc evaporation. Using scanning electron microscopy and X-ray diffraction, a grain refinement with increasing Al content up to x = 0.65 could be observed, while the coating with the highest Al content of x = 0.78 showed again a coarser grain size. The presence of a single phase face-centered cubic (fcc)-structure up to an Al content of x = 0.49 was confirmed by X-ray diffraction. Ti0.44Al0.56N and Ti0.35Al0.65N exhibited a dual phase fcc- and wurtzitic (w)-structure, where for the latter the w-structure is dominating. A single phase w-structure was observed for the Ti0.22Al0.78N coating. Nano-indentation experiments revealed an increasing hardness with increasing Al content up to x = 0.56 and thus, as long as the fcc-phase is dominating, due to decreasing grain size and increasing compressive stress. For the coatings with dominating and pure w-structure a drop in hardness was observed. Similar to the hardness, the micromechanical bending tests also revealed improving fracture properties with increasing Al content up to x = 0.56 and deteriorating fracture properties when the w-structure becomes dominant.
U2 - 10.1016/j.surfcoat.2022.128690
DO - 10.1016/j.surfcoat.2022.128690
M3 - Article
SN - 0257-8972
VL - 444.2022
JO - Surface & coatings technology
JF - Surface & coatings technology
IS - 25 August
M1 - 128690
ER -