D. Heger

Magnetic response of (Cr,Al,Si)N nanocrystallites on the microstructure of Cr—Al—Si—N nanocomposites

Abstract A combination of microstructure analysis and ab initio calculations helped us to describe the interplay between the microstructure of Cr—Al—Si—N thin film nanocomposites and the ordering of the magnetic moments in the chromium-rich phase of (Cr,Al)N. The microstructure of the Cr—Al—Si—N nanocomposites was modified through the degree of ionisation of the deposited species in three physical vapour deposition processes – cathodic arc evaporation, unbalanced magnetron sputtering and high power impulse magnetron sputtering. According to the results of the ab initio calculations, the magnetic ordering was concluded from the expansion of the elementary cell and from the change of the crystal anisotropy of the elastic constants of (Cr,Al)N; these microstructure features were obtained from X-ray diffraction experiments. The microstructure of the Cr—Al—Si—N nanocomposites was furthermore characterised using the combination of X-ray diffraction and transmission electron microscopy with high resolution in order to obtain information about the phase composition of the thin films, distribution of individual elements and the crystallite size.

On the preferred orientation in Ti1 – xAlxN and Ti1– x – yAlxSiyN thin films

Abstract The influence of the deposition geometry and the chemical composition on the form and degree of the preferred orientation of crystallites was investigated in TiN, Ti1–xAlxN, and Ti1–x–yAlxSiyN thin films deposited by cathodic arc evaporation. The deposition geometry was varied by changing the angle between the cathodes and the substrates. The chemical composition of the thin films was modified by the choice of the cathodic materials. In TiN thin films, the crystallites were preferentially oriented with the {111} direction perpendicular to the sample surface, independent of the deposition geometry. Besides, a well-pronounced in-plane texture was observed. Co-deposition of Ti, Al, and Si in nitrogen atmosphere stimulated inclination of the texture direction towards the sample surface, which can be described as a change of the texture direction related to the sample surface perpendicular direction, and reduced the amount of the in-plane texture in the coatings (the preferred orientation of crystalli...

Modification of the Diffusion Process in the Iron-Aluminum System via Spark Plasma Sintering/Field Assisted Sintering Technology

The influence of Spark Plasma Sintering / Field Assisted Sintering Technology applying pulsed direct current up to the root-mean-square current densities of 129 A/cm2 on the interfacial reactions in Al - Fe - Al stacks was investigated at temperatures between 500°C and 600°C. Independently of the current density and current direction, thin Al13Fe4 and wide Al5Fe2 phases were detected in the diffusion couples. The Al5Fe2 phase consisted of columnar grains having a {001}-fiber texture. Al13Fe4 was found in the form of discontinuous spots at the Al/Al5Fe2 interface. The interface between Al5Fe2 and Fe was highly fringed. The layer growth kinetics of Al5Fe2 was parabolic. The growth rate was strongly enhanced in the SPS/FAST experiments as compared to the conventional diffusion experiments, independently, on the current direction. It is suggested that the enhanced growth rates are a result of temperature gradients existing in a typical Spark Plasma Sintering device. Possible effects of thermomigration and electromigration are discussed.

Calculation Of The Interdiffusion Coefficient In The Cu‐Zn Diffusion Couple

A quantitative analysis of multiphase diffusion in Cu‐Zn diffusion couple is presented. The analysis is based in using the concentration profiles provided by electron micro‐beam analyzer. From the dependence of the square of phase thickness from annealing time, the growth constant for each phase in each annealing temperature can be calculated. Knowing the growth constant of γ and e phases one can calculate the activation energy and the diffusion coefficient of the above mentioned intermetallic phases.