Ti1−x Al x N
metastable ceramic phases
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract Metastable, single phase, polycrystalline Ti1−x Al x N hard layers were deposited on HSS-substrates with reactive magnetron sputtering ion plating (MSIP). The substrate temperature was 400 °C, the bias −60 V, the argon pressure 1.2 Pa and the sputter power 6 W cm−2. Compound targets with a Ti:Al ratio of 75/25, 50/50 and 25/75, expressed in at-%, were sputtered. The nitrogen reactive gas pressure during sputtering was 8.4 × 10−2 Pa for the 75∶25 target and 1.08 × 10−1 Pa for the 50∶50 and 25∶75 targets. The Ti1−x Al x N layers grew with x=0.26, 0.54 and 0.75, as determined with EPMA. Thin film XRD and HEED structure analysis showed that the Ti0.74Al0.26N layer had grown as B1 structure (a0∶0.4214 nm) with  texture, the Ti0.46Al0.54N layer likewise as B1 structure (a0∶0.4154) with  texture, but the Ti0.25Al0.75N as B4 structure (a0∶0.317 nm and c0∶0.5014 nm) with  texture. Pronounced columnar growth was observed with HR-SEM in the fractured surface of the cubic layers. The mean grain size, and consequently the surface roughness, diminished with increasing Al-content of the layer.
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