Analysis of hardness of nanocrystalline coatings of aluminum-rich Ti1−ð�?�¥Al𝑥N

[摘要] Titanium aluminum nitride coatings were fabricated by a d.c.magnetron sputtering system from a Tiâ€�?�Al (60/40wt%) target. Coatings were deposited on steel substrates, at a substrate temperature of 250 °C and a bias voltage of â€�??80 V. The nitrogen flow was varied from 1.5â€�??6 sccm and the Ar flow was kept constant at 20 sccm. The morphology and microstructure of the coatings were analysed by X-ray diffraction and scanning electron microscopy. The results of X-ray diffraction showed the presence of two cubic crystalline phases, TiN and AlN, which were confirmed by X-ray photoelectron spectroscopy. The Vicker hardness was obtained by the effective model of indentation. It was observed that the hardness of the coatings decreases from 22.8â€�??9.5 GPa with an increased nitrogen content from 1.5â€�??4.5 sccm. Subsequently, the hardness increased to 22.1 GPa by increasing nitrogen to 6 sccm. The behavior of hardness with grain size variation is consistent with the Hall-Peth relationship. The high value in the hardness of the coatings is mainly attributed to small grain sizes and the compressive stress present.

[学科分类] 材料工程

[关键词] Hard coatings;hardness;fracture toughness;Tiâ€�?�Alâ€�?�N.