TY - JOUR
T1 - Evolution of microstructure and mechanical properties of a graded TiAlON thin film investigated by cross-sectional characterization techniques
AU - Schalk, Nina
AU - Tkadletz, Michael
AU - Terziyska, Velislava L.
AU - Deluca, Marco
AU - Letofsky-Papst, Ilse
AU - Keckes, Jozef
AU - Mitterer, Christian
PY - 2019/2/15
Y1 - 2019/2/15
N2 - In the last years, quaternary oxynitrides have emerged as a new class of materials due to their tunable properties. Within the present work, a graded TiAl(O)N film was grown by magnetron sputter deposition, using TiAl targets with a Ti/Al atomic ratio of 40/60, constant nitrogen and stepwise increasing oxygen partial pressure over the film thickness. The microstructural evolution of the film was investigated by transmission electron microscopy and synchrotron X-ray nanodiffraction. Complementary, cross-sectional μ-Raman spectroscopy was performed to further validate the phase evolution. The first layer, grown without the addition of oxygen, showed a prevalent wurtzite (w) structure and a subordinate face centered cubic (fcc) phase fraction. The addition of small amounts of oxygen resulted in the stabilization of the fcc-phase and the w-phase vanished. With increasing film thickness and thus, increasing oxygen content, increasing amounts of an additional amorphous phase fraction were observed. In the first layers, tensile in-plain strain was determined, which turns to compressive towards the film surface. Cross-sectional nanonindentation revealed increasing hardness and elastic modulus with increasing oxygen content in the first layers as a result of the w to fcc transition; however, towards the film surface the hardness decreases, which can be related to the increasing amorphous phase fraction.
AB - In the last years, quaternary oxynitrides have emerged as a new class of materials due to their tunable properties. Within the present work, a graded TiAl(O)N film was grown by magnetron sputter deposition, using TiAl targets with a Ti/Al atomic ratio of 40/60, constant nitrogen and stepwise increasing oxygen partial pressure over the film thickness. The microstructural evolution of the film was investigated by transmission electron microscopy and synchrotron X-ray nanodiffraction. Complementary, cross-sectional μ-Raman spectroscopy was performed to further validate the phase evolution. The first layer, grown without the addition of oxygen, showed a prevalent wurtzite (w) structure and a subordinate face centered cubic (fcc) phase fraction. The addition of small amounts of oxygen resulted in the stabilization of the fcc-phase and the w-phase vanished. With increasing film thickness and thus, increasing oxygen content, increasing amounts of an additional amorphous phase fraction were observed. In the first layers, tensile in-plain strain was determined, which turns to compressive towards the film surface. Cross-sectional nanonindentation revealed increasing hardness and elastic modulus with increasing oxygen content in the first layers as a result of the w to fcc transition; however, towards the film surface the hardness decreases, which can be related to the increasing amorphous phase fraction.
KW - Cross-sectional nanoindentation
KW - Graded film
KW - Sputtering
KW - Synchrotron X-ray nanodiffraction
KW - TEM
KW - TiAlON
UR - http://www.scopus.com/inward/record.url?scp=85058775222&partnerID=8YFLogxK
U2 - 10.1016/j.surfcoat.2018.12.058
DO - 10.1016/j.surfcoat.2018.12.058
M3 - Article
AN - SCOPUS:85058775222
SN - 0257-8972
VL - 359
SP - 155
EP - 161
JO - Surface and Coatings Technology
JF - Surface and Coatings Technology
ER -