Ivan Kohutek

The austenite-ferrite transformation temperatures evaluated by dilatometry using thermo-mechanical simulator Gleeble 1500D are investigated in this paper. The effect of cooling rates 1, 5, 10 and 15°C/s on the upper and lower critical transformation temperatures was evaluated for 30 specimens of six material groups. Considering the cooling rate fro...

The aim of the article was to evaluate the microstructural parameters of Cu–Al2O3 dispersion strengthened materials with different volume fraction of Al2O3 phase. For analyses of dispersoids Al2O3, the extraction carbon replica was used. The distribution of Al2O3 particles in the matrix was estimated by three methods (quadrant count method, polygon...

A review starting from material science trough production technology to testing properties of the CuAl2O3 system, based on several years of research and development in materials research, is presented. Microstructural parameters and strength and plastic properties at higher temperatures are presented and the failure mechanism described. Influence o...

The method of "in-situ tensile testing in SEM" is suitable for investigations of fracture mechanisms because it enables to observe and document deformation processes directly, and so the initiation and development of plastic deformation and fracture can be reliably described. With increasing tensile load, local cracks are formed by rupture of large...

Al-Al4C3 dispersion strengthened material was prepared by a powder metallurgy method of reaction milling. Interparticle distances of Al4C3 particles in the Al-Al4C3 composite materials were evaluated. In this paper, nearest neighbour distribution function, polygonal methods and the quadrate counts method are used for characterization of particle ar...

Microstructural parameters of Cu-Al 2 O 3 dispersion strengthened materials were evaluated in the paper. Using the extraction carbon replica for analyses of Cu-Al 2 O 3 (1-10 vol.%) system, it was shown that the majority phase of dispersoids were the Al 2 O 3 particles of 60 nm average diameter, which were distributed individually or in clusters of...

Metallographic analysis of the primary austenitic grain of carbon steels after various thermal treatment is carried out. Two methods are examined in detail: the ASTM recommended procedure and the recently proposed method based on stochastic simulations of convex space filling systems. The difference between the profile size and 3D grain size estima...

Qualitative and quantitative analyses of two types of unidirectional carbon-carbon composites together with fractographic investigation and room temperature bending strength measurements were performed. Methodical aspects of the quantitative estimation of microstructure parameters were discussed. The reliability of the performed image analysis was...

TEM images of thin foils with quasi-globular particles are examined by means of two methods of spatial statistics. The spatial arrangement of particle reference points is described by means of quadrat count statistics and by polygonal method (the analysis of the Voronoi mosaic generated by patterns of particle reference points). A good agreement be...

TEM images of thin foils with quasi-globular particles are examined by means of two methods of spatial statistics. The spatial arrangement of particle reference points is described by means of its shape with quadrat count statistics and by polygonal method (the analysis of the Voronoi mosaic generated by patterns of particle reference points). A go...

In the contribution possibilities of evaluation of the quantities connected with microstructural grain layouts are discussed in the case of heterogenous grain size distributions. The microstructures of real materials together with the etalon and computer simulated structures were used. The following theoretical models were applied: planar Voronoi t...