Nickel Alloys in Directionally Solidified State – Characterisation of Microstructure and Phase Composition of the Alloys

Abstract:

The paper deals with the characterisation of the structure and phase composition of selected types of nickel alloys. Experimental alloys were prepared by vacuum induction casting. Castings were directionally solidified in corundum tubes with specified apex angle in the two-zone crystallisation furnace. Rate of directional solidification was 100 mm/h. Observation was carried out on the samples in the as-cast and directed state. Influencing of the structure by the process of directional solidification is evident. Porosity and micro-hardness were determined in transverse and longitudinal sections of individual samples and character of the formed structures was evaluated. Microstructural characterisation of materials was performed with use of scanning electron microscope. Distribution of individual elements was captured on X-ray maps, which documented significant chemical heterogeneity of investigated samples. Matrix composition corresponds approximately to the nominal composition of the alloys. The alloys contain moreover with variable content of primary and alloying elements. In the alloys with molybdenum and zirconium the phase enriched by these alloying elements were detected. On the other hand chromium is evenly dispersed in the basic matrix and it does not accumulate in the phases.

• Periodical: Materials Science Forum (Volume 782)
• Pages: 441-444
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.782.441
• Online since: April 2014
• Authors: Jitka Malcharcziková*, Miroslav Kursa, Martin Pohludka
• Keywords: Directional Solidification, Nickel Alloy, Phase Composition, Structure

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