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M. Lachowicz, K. Haimann, M. Lachowicz, R. Jasionowski and S. Pawlak

Abstract

This paper presents the results of investigation of four cast alloys based on the Fe3Al intermetallic phase. Microstructure tests using light microscopy, electron scanning microscopy and X-ray diffraction methods, have been performed. On this basis, a presence of particles rich in zirconium and molybdenum, and in case of the alloy with 28 at.% aluminium and 5 at.% chromium — the presence of sigma phase (FeCr), has been found. Also, the results of the study of the microstructure influence on the electrochemical corrosion resistance in the 5 % NaCl solution have been presented. The Fe-26Al-2Cr-1Mo-0.1Zr-0.005B at.% and Fe-26Al-5Cr-1Mo-0.1Zr-0.005B at.% alloys exhibited increased corrosion resistance in comparison to the Fe-23Al-1Mo-0.1Zr-0.005B at.% alloy without chromium addition. The appearance of the sigma phase in the alloy of Fe-28Al-5Cr-1Mo-0.1Zr-0.005B at.% chemical composition resulted in lowering the corrosion resistance of this alloy and a change in corrosion character from the pitting to the intercrystalline one.

Open access

J. Kowalski, J. Pstruś, S. Pawlak, M. Kostrzewa, R. Martynowski and W. Wołczyński

Influence of the Reforging Degree on the Annihilation of the Segregation Defects in the Massive Forging Ingots

The structural zones of the forging ingot have been distinguished. Some segregation defects within these zones have been described. An observation of the defects has been carried out with the use of scanning microscopy and scanning acoustic microscopy. Some defects revealed by the scanning acoustic microscopy have been subjected to the 3D computer visualization. A difference between localization and difference between morphology of carbides precipitated in the columnar structure and equiaxed structure has been shown. A given ingot was subjected to the plastic deformation with different reforging degree. The samples were taken from different segments of the reforged ingot. A density was determined for each ingot segment. A degree of consolidation was determined after ingot reforging. Once again the scanning acoustic microscopy was applied to determine the annihilation of the segregation defects in the forging ingot structure. A new definition of the consolidation factor after the reforging has been proposed.

Open access

J.T. Bonarski, L. Tarkowski, S. Pawlak, A. Rakowska and Ł. Major

Abstract

Performed investigations and obtained results concerned the analysis of residual stresses in near-surface areas of coppercorundum (Cu-Al2O3) composite and silicon carbide (SiC) samples. X-ray diffraction and acoustic tomography techniques, as well as the suitable calculation procedures, allowed to locate sample-areas with extreme values of stresses residing in the examined materials. The registered texture-stress characteristics reflects inhomogeneity of the samples structure identified by means of acoustic tomography. Obtained results provide valuable information on anisotropy of physical properties of structural elements produced by the technologies applied to the examined samples.