Institute of Metallurgy of Ural Branch of Russian Academy of Sciences, Ekaterinburg, Russia:

P. V. Kotenkov, Post-Graduate Student, e-mail: p.kotenkoff@mail.ru
E. A. Popova, Senior Researcher
E. A. Pastukhov, Head of Laboratory, Correspondent Member of Russian Academy of Sciences
A. S. Bykov, Senior Researcher

There is researched the “Survivability” of Al – Zr – Sc master alloy or stability of grain size refinement effect of Al – 4% Cu alloy by additions of 0.5% (Sc + Zr), entered with experimental master alloy. The Al – 1.1% Zr – 1.1% Sc master alloy (received earlier) is characterized by complex aluminides Al₃(Sc_xZr_1–x), which have the cubic lattice of the structural L12 type, coinciding with α-Al-type lattice. Usage of master alloys for grain refinement of aluminium alloys is an important factor for matching of nucleating phases and matrix regarding dimensional and structural lattices. Sc replacement by Zr in aluminides reduces their dimensional discrepancy and moves the eutectic point in ternary system towards smaller Sc + Zr values, which allows to save expensive Al – Sc master alloy with preservation of scandium positive influence on strength and plastic properties. The knowledge about stability of performance of the master alloys (particularly, the invariance of modifying effect during soaking of melt with master alloy), is also required. The Al – 4% Cu alloy was used for the study of modifying performance of experimental master alloy via the method of sampling during soaking and metallographic analysis of samples. The structure of the Al – 4% Cu model alloy during soaking in a liquid state during 6 hours is characterized by large grain sizes (1–5 mm). It is shown that addition of Al – Sc – Zr master alloy (0.5% Sc + Zr in alloy) results in significant decrease of grain size. The modifying effect is appeared even after 30 min of soaking (the grain size is 300–350 μm) and peaks at 1 hour soaking (the grain size is 13–35 μm). Stability of master alloy performance is more than 6 hours of soaking at 700–720 ^oC. It means that it is possible to provide the pouring of melt without loss of modifying effect. The results can be used in plants that produce high-quality aluminium alloys.

1. Goldshteyn Ya. E., Mizin V. G. Inokulirovanie zhelezo-uglerodistykh splavov (Inoculation of iron-carbon alloys). Moscow : Metallurgiya, 1993. 416 p.
2. Popova E. A., Shubin A. B., Kotenkov P. V., Bodrova L. E., Dolmatov A. V., Pastukhov E. A., Vatolin N. A. Rasplavy — Melts. 2011. No. 1. pp. 11–15.
3. Zakharov V. V., Rostova T. D. Metallovedenie i termicheskaya obrabotka metallov — Metal Science and Heat Treatment. 1995. No. 2. pp. 23–27.
4. Knipling K. E., Karnesky R. A., Lee C. P., Dunand D. C., Seidman D. N. Precipitation evolution in Al – 0.1Sc, Al – 0.1Zr and Al – 0.1 Sc – 0.1 Zr (at.%) alloys during isochronal aging. Acta Materialia. 2010. Vol. 58. pp. 5184–5195.
5. Royset J., Ryum N. Scandium in aluminium alloys. International Materials Reviews. 2005. Vol. 50, No. 1. pp. 19–44.
6. Brodova I. G., Popel P. S., Barbin N. M., Vatolin N. A. Rasplavy kak osnova formirovaniya struktury i svoystv alyuminievykh splavov (Melts as a base of formation of structure and properties of aluminium alloys). Ekaterinburg : Ural Branch of Russian Academy of Sciences, 2005. 372 p.
7. Maltsev M. V. Modifitsirovanie struktury metallov i splavov (Modification of structure of metals and alloys). Moscow : Metallurgiya, 1964. 214 p.
8. Bykov A. S., Popova E. A., Kotenkov P. V., Pastukhov E. A. Kalorimetricheskoe opredelenie soderzhaniya neravnovesnoy evtekticheskoy fazy v medsoderzhashchikh splavakh na osnove alyuminiya (Calorimetric definition of the content of nonequilibrium eutectic phase in copper-containing alloys on the basis of aluminium). Kompyuternoe modelirovanie fiziko-khimicheskikh svoystv stekol i rasplavov: Trudy XI Rossiyskogo seminara (Computer modeling of physical-chemical properties of glass and alloys: proceedings of the XI Russian seminar). Kurgan : Publishing House of Kurgan State University, 2012. pp. 64–67.
9. Napalkov V. I., Makhov S. V. Legirovanie i modifitsirovanie alyuminiya i magniya (Alloying and modification of aluminium and magnesium). Moscow : MISiS, 2002. 376 p.