Control of Microstructure and Texture in Nanocrystalline Transition -Metal Nitride Coatings by Ion Beam Assisted Deposition Method

In this study, titanium nitride (TiN), chromium nitride (CrN) and vanadium nitride (VN) were prepared by ion-beam-assisted deposition method (IBAD). The film microstructure was observed using scanning electron microscopy (SEM). The results showed that the microstructure was controlled by homologous temperature (TS/TM), and mostly followed by the structure zone diagram summarized by Thornton and Messier. The ion beam assistance could accelerate the transition from Zone 1 to Zone T, and Zone T to Zone 2. In addition, the ion beam increased the packing density and the reactivity of Cr and N. The grain sizes, determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), were in nano-scale (∼15nm) when ion to atom ratio (J I/JM) = 2. Results of XRD pole figures showed that the films were highly textured. By the control of ion beam energy, JI/J M ratio, incident angle, and the deposition temperature, seven kinds of textures were observed. Four parameters, (1) surface energy, (2) strain energy, (3) adatom mobility, (4) preferential sputtering and differential damage, were identified and used to explain the texture evolution of the films. Results of nanohardness, measured by nanoindentation, indicated that the hardness of the films is not related to the film texture, which suggested that the dislocation theory is not applicable for the nano-sized grains. The minimum grain size required for the activation of slip systems in grains, was estimated to be ∼100nm. The grain rotational deformation and grain boundary sliding followed by mass transfer could be two possible mechanisms of deformation in the nanocrystalline films.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Materials Science and Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Ma, Cheng-Hsin

Contributors dc:contributor

• Chen, Haydn

• Engineering, Materials Science

Language dc:language

eng

Identifier

(MiAaPQ)AAI3070027

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/82722