The influence of various titan-containing grain refiners on an AlZn20-alloy was examined using thermal analysis, light microscopy and scanning electron microscopy, and evaluation of grain size. The aim of this study was to determine microstructural features. The study showed that the magnitude of the melts undercooling, initial temperatures of primary nucleation and grain refinement are highly influenced by the grain refiner used.
PL
W pracy badano wpływ różnych zapraw modyfikujacych, zawierających tytan, na strukturę stopu AlZn20. W badaniach stosowano techniki analizy termicznej, mikroskopii świetlnej i elektronowej oraz analizę wielkości ziarna. Badania wykazały, że wielkość przechłodzenia i cechy struktury stopu zmodyfikowanego silnie zależą od rodzaju użytego modyfikatora.
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The paper brings information about inoculation process of the sand-cast binary Al-20 wt% Zn (AlZn20) alloy, inoculated with Ti-containing grain-refiners, i.e. AlTi5B1, AlTi3C0.15 and (AlZn)-Ti3 master alloys (MA). During the experiments thermal analyses (TA) and differential scanning calorimetry (DSC) were used. Macrostructure observations were performed using light microscopy (LM). On the basis of the performed examinations it was found that all the MAs used in this work caused significant grain refinement, which initiates via a heterogeneous nucleation mode. The obtained structure fineness of the inoculated AlZn20 alloy should positively influence its ductility, which is of great importance for the practical application of this group of foundry alloys.
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Purpose: The main purpose of this paper is presenting the results obtained in years 2007 – 2010 in frame of the project Marie Curie Transfer of Knowledge – CastModel. The project was focused, among others, at elaborating new, environmentally friendly cast alloys based on the Al-Zn system. Particularly, efforts were aimed at improving ductility of the sand cast high-zinc aluminium alloys (HZnAl) by using the newly elaborated master alloys, based on the Al-Zn-Ti system. Design/methodology/approach: The presented work is focused on the nucleation of the high-zinc Al-20 wt% Zn (HZnAl AlZn20) alloy, known as the high damping one, aiming at improving plastic properties of the sand castings. The melted alloy was nucleated with AlTi5B1 (TiBAl) and AlTi3C0.15 (TiCAl) refiners as well as with the newly introduced ZnAl-Ti3 one. During the research the following experimental techniques were used: LM, SEM-EBSD, EDS, TA, DSC, Quantitative Metallography, UTS, Elongation and Attenuation coefficient measurements. Findings: During the performed examinations it was found out that significant increasing of the grain population of the inoculated alloy increases plasticity represented by elongation. The attenuation coefficient of the nucleated alloy, measured using an Olympus Epoch XT device, preserves its high value. The results obtained allow to characterize the examined AlZn20 alloy as promissive, having good strength and damping properties as well as the environmentally friendly alloy because of its comparatively low melting temperatures. Practical implications: The grain-refined high-zinc aluminium alloys can be used as the high damping substitutes of the traditional, more energy consumable Fe-based foundry alloys. Originality/value: The newly elaborated ZnAl-Ti based master alloys show high refining potency and quick dissolution in low melting temperatures of about 500°C, and are the promissive alternatives of the traditional AlTi-based ones.
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