MALCHARCZIKOVÁ Jitka VSB-Technical University of Ostrava

Spoluautoři MICHENKA Vít, POHLUDKA Martin, KAŇÁK David, FRIDRICH René

Selected nickel alloys were melted by vacuum induction melting (VIM). Samples were melted and cast under vacuum into the shape of rods with diameter of 10 mm. Thus prepared castings were directionally solidified at the rate of 100 mm/h in order to eliminate casting defects. Flaw detection tests were performed on the samples in the directionally oriented condition. Thus prepared samples did not contain any casting defects and they were used for determination of the basic mechanical properties and fracture characteristics at room temperature. It is evident after comparison of the tensile diagrams of experimental alloys that the alloys based on IC396, IC221M and IC438 and have similar character of failures. The sample based on the alloy IC50 exhibits with comparison with other alloys lower yield strength, the value of which is almost half. The alloy exhibits very high ductility and higher strength than the other alloys, but its low yield strength limits the possibilities of its practical use. The alloy IC396 has, however, significantly improved ductility compared to the alloys IC221M and IC438. Porosity and micro-hardness was also determined in these samples. Porosity and micro-hardness results do not show significant differences at measurements in transverse and longitudinal direction. Evaluation of the phase composition was performed on an analytical scanning microscope. Matrix composition corresponds approximately to the nominal composition of the alloys. The alloys contain furthermore phases with variable content of basic and alloying elements. The obtained results will be used as input information for further laboratory and pilot testing.

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