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The paper presents the results of evaluation of the metallurgical quality of master heat ingots and of the identification of non-metallic inclusions (oxides of Al., Zr, Hf, Cr, etc.), which have been found in the shrinkage cavities formed in these ingots. The inclusions penetrate into the liquid alloy, and on pouring of mould are transferred to the casting, especially when the filtering system is not sufficiently effective. The specific nature of the melting process of nickel and cobalt alloys, carried out in vacuum induction furnaces, excludes the possibility of alloy refining and slag removal from the melt surface. Therefore, to improve the quality of castings (parts of aircraft engines), it is so important to evaluate the quality of ingots before charging them into the crucible of an induction furnace. It has been proved that one of the methods for rapid quality evaluation is an ATD analysis of the sample solidification process, where samples are taken from different areas of the master heat ingot. The evaluation is based on a set of parameters plotted on the graph of the dT/dt derivative curve during the last stage of the solidification process in a range from TEut to Tsol.

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A quantitative description of overlaps on fractures in sialon ceramics, is presented in the paper. A conventional analysis, aiming at the determination of the percentage share of overlaps on the basis of quantitative fractography, was preceded by stereometric/fractal analyses. They enabled the selection of representative sections of samples and then, the production of transverse microsections in those places for an analysis of the fractures’ profiles using the light microscopy method and fractographic image analysis. Based on the compared results from both methods, a successful verification was made of the research methodology developed earlier for sintered carbides and proven for a chromium-molybdenum steel.

The subject matter of the paper is the quantitative evaluation of gaseous and shrinkage porosity in construction elements of a low-pressure aircraft engine turbine using quantitative metallography methods. The research material consisted of blades and blade segments with a polycrystalline structure made of IN 713C and MAR M247 superalloys.One of the major problems that occur in the precision castings is their porosity: gaseous, which is the result of emission of dissolved gases from the superalloy during solidification, and shrinkage, being the result of shrinkage of the superalloy and from a lack of feeding of the interdendritic space.The comprehensive procedure of porosity evaluation includes: an automatic decimal-to-binary conversion of pores, a selective quantitative evaluation of gaseous and shrinkage porosity, the development of measuring conditions of quantitative metallography parameters, and the application of structural maps showing the varied porosity distribution over the cross-sections of castings of blades and blade segments.The developed practical procedure of selective measurement of gaseous and shrinkage porosity in the examination of precision castings made of high-temperature creep resisting nickel superalloys is presented.