Pacific National University, Khabarovsk, Russia:

E. H. Ri, Head, Chair of Foundry and Process Metallurgy
Khosen Ri, Professor, Chair of Foundry and Process Metallurgy
A. V. Goncharov, Post-Graduate Student, Chair of Foundry and Process Metallurgy

National University of Science and Technology “MISiS”, Moscow, Russia:

V. B. Deev, Professor, Chair of Foundry Technologies and Artistic Processing of Materials, e-mail: deev.vb@mail.ru

This paper describes the developed technology for obtaining master alloys based on nickel and rare earth (REM) aluminides. There were used a complex modifier AKTse (АКЦе) (composition, % (wt.): 30–33 Al, 28–30 REM, 3–4 Ca, reminder — Ni), produced by Complex Modifiers Ltd, and A7 grade aluminum (impurities sum of Si and Fe <0.3% (wt.)) for master alloys creation. Two methods are proposed for obtaining master alloys. The first one is the saturation of liquid aluminum with a complex AKTse modifier at 1400 ^оC to a content of 60% (wt.) in increments of 10% (wt.). The second one is the saturation of molten complex modifier AKTse with aluminum at 1400 ^оC to a content of 60% (wt.) in increments of 10% (wt.). Regardless of the method for master alloys obtaining with additives of 60% (wt.) AKTse or A7, the content of the main alloying elements which are Al, Ni, REM practically does not vary. The average chemical composition of the master alloy, % (wt.), is the following: 68.1 Al; 1.15 Ca; 20.0 Ni; 12.25 REM (3.82 La, 8.43 Ce). The first method of master alloys A7 — AKTse obtaining can be considered more rational. Intermetallic compounds such as nickel aluminides (Al₃Ni) and REM (Al₁₁REM₃) crystallize in pure argon atmosphere with the addition of 50–60% (wt.) AKTse in liquid aluminum at 1400 ^оC. With the help of electron microscopy and X-ray spectrum analysis, nickel and REM aluminides were identified, their microhardness is determined. It was found that increase of a master alloy (A7 + 60% AKTse (wt.)) addition in molten aluminum leads to increase of the crystallization start temperature to ~825 ^оC, and intermetallic phases τ_cr crystallization time increases in accordance with expansion of the crystallization temperature range. In this case, eutectic crystallization start temperature t_e and the duration of this processe decrease dramatically. Also the synthesized alloying composition influence with Ni and REM aluminides on the structure formation, the character of elements distribution and the microhardness of the structural components of the solid α-solution and eutectic in the AK7ch (AK7ч) alloy was studied in this paper. The increase in the addition of a master alloy leads to an increase in the microhardness of the solid α-solution and the eutectic. The formation features of four types of various chemical compositions of quasi-eutectics are determined:
1) solid α-solution + Si;
2) solid α-solution + Si + Fe + Mn;
3) solid α-solution + Si + Fe, but without Mn;
4) modified eutectic, contains all the components of the master alloy.
The crystallization of Ni and REM aluminides, which have a high microhardness, is possible in the modified eutectic 4. The total eutectic microhardness depends on: the ratio of 1–4 eutectic distribution as well as the amount and dispersity intermetallic compounds.

The research was carried out with the sponsorship of the Ministry of Education and Science of the Russian Federation within the fulfilment of government assignments (No. 11.7208.2017 / 7.8, 11.3014.2017 / 4.6 and 11.7213.2017 / 7.8) on the equipment of the Chair of Foundry and Process Metallurgy and the Centre of Collective Usage for Applied Materials Science, Pacific National University.

1. Shalin R. E. High-temperature alloys for gas turbines. Moscow : Metallurgiya, 1981. 480 p.
2. Povarova K. B. Physical-and-chemical principles for the development of thermally stable alloys based on transition metal aluminides. Materialovedenie. 2007. No. 12. pp. 20–27.
3. Dobatkin V. I., Elagin V. I., Fedorov V. M. Rapid crystallized aluminum alloys. Moscow : VILS, 1995. 341 p.
4. Belov N. A., Alabin A. N. Perspective aluminum alloys with increased heat resistance for valve industry as possible alternative to steels and cast irons. Materialy v mashinostroenii. 2010. No. 2 (65). pp. 50–54.
5. Hyde K. B., Norman A. F., Prangnell P. B. The effect of Ti on grain refinement in Al – Sc alloys. Material Science Forum. 2002. Vol. 396–402. pp. 39–44.
6. Min Song, Yuehui He, Shanfeng Fang. Effect of Zr content on the yield strength of an Al – Sc alloy. Journal of Materials Engineering and Performance. 2011. Vol. 20, No. 3. pp. 377–381.
7. Dalen M. E., Dunand D. C., Seidman D. N. Effects of Ti additions on the nanostructure and cree properties of precipitation-strengthened Al – Sc alloys. Acta Materialia. 2005. Vol. 53, No. 15. pp. 4225–4235.
8. Norman A. F., Prangnell P. В., McEwen R. S. The solidification behavior of dilute aluminium-scandium alloys. Acta Materialia. 1998. Vol. 46, No. 16. pp. 5715–5732.
9. Marquis E. A., Seidman D. N. Nanoscale structural evolution of Al₃Sc precipitates in A1 (Sc) alloys. Acta materialia. 2001. Vol. 49. pp. 1909–1919.
10. Royset J., Ryum N. Scandium in aluminium alloys. International Materials Review. 2005. Vol. 50, No. 1. pp. 19–44.
11. Harada Y., Dunand D. C. Microstructure of Al₃Sc with ternary transition-metal additions. Materials Science and Engineering: A. 2002. Vol. 329–331. pp. 686–695.
12. Ri Khosen, Ri E. Kh., Zernova T. S., Kalaushin M. A., Ri V. E. Conditioning Agent. Patent RF, No. 2521915. Applied: 28.11.2011. Published: 10.06.2014. Bulletin No. 16.
13. Belov N. A., Naumova E. A. Structure and properties of alloys based on the aluminum-cerium system. Perspektivnye materialy. 1999. No. 6. pp. 47–56.
14. Belov N. A., Khvan A. V. Structure and mechanical properties of eutectic composites based on the Al – Cu – Ca system. Tsvetnye Metally. 2007. No. 2. pp. 91–94.
15. Akopyan T. K., Belov N. A. Approaches to the design of the new highstrength casting aluminum alloys of 7xxx series with high iron content. Non-ferrous Мetals. 2016. No. 1. pp. 20–27.
16. Belov N. A., Akopyan T. K., Mishurov S. S., Korotkova N. O. Effect of Fe and Si on the microstructure and phase composition of the aluminiumcalcium eutectic alloys. Non-ferrous Мetals. 2017. No. 2. pp. 37–42.
17. Belov N. A., Batyshev K. A., Doroshenko V. V. Microstructure and phase composition of the eutectic Al – Ca alloy, additionally alloyed with small additives of zirconium, scandium and manganese. Non-ferrous Мetals. 2017. No. 2. pp. 49–54.
18. Srirangam P., Chattopadhyay S., Bhattacharya A., Nag S., Kaduk J., Shankar S., Banerjee R., Shibata T. Probing the local atomic structure of Sr-modified Al – Si alloys. Acta Materialia. 2014. Vol. 65. pp. 185–193.
19. Chengwei Liao, Jianchun Chen, Yunlong Li et al. Modi+cation performance on 4032 Al alloy by using Al – 10 Sr master alloys manufactured from different processes. Progress in Natural Science Materials International. 2013. Vol. 24, No. 2. pp. 87–96.
20. Li Zhenghua, Yan Hong. Modification of primary α-Al, eutectic silicon and β-Al₅FeSi in as-cast AlSi₁₀Cu₃ alloys with (La + Yb) addition. Journal Of Rare Earths. 2015. Vol. 33, No. 9. P. 995.
21. Aguirre-De la Torre E., Pérez-Bustamante R., Camarillo-Cisneros J., Gómez-Esparza C. D., Medrano-Prieto H. M., Martínez-Sánchez R. Mechanical properties of the A356 aluminum alloy modified with La/Ce. Journal Of Rare Earths. 2013. Vol. 31, No. 8. pp. 811–816.
22. Berngardt V. A., Fedorova O. V. Investigation of the influence of zirconium and REM on the structure and properties of aluminum rod. III International Scientific School for Youth “Material Science and Metal Physics of Light Alloys”. Ekaterinburg, December 8–12, 2014. Ekaterinburg : UrFU, 2014. pp. 50–55.
23. Ibrahim M. F., Alkahtani S. A., Abuhasel Kh. A., Samuel F. H. Effect of intermetallics on the microstructure and tensile properties of aluminum based alloys: Role of Sr, Mg and Be addition. Materials and Design. 2015. No. 86. pp. 30–40.
24. Belov N. A. Cast Aluminum-Base Alloy. Patent RF, No. 2001145. Published: 15.11.1993. Bulletin No. 37/38.
25. Belov N.A. Structure and hardening of casting alloys of aluminumnickel-zirconium systems. Metal Science and Heat Treatment. 1993. No. 10. pp. 19, 20.
26. Belov N. A., Alabin A. N. Perspective aluminum alloys with additives of zirconium and scandium. Tsvetnye Metally. 2007. No. 2. pp. 99–106.
27. Belov N. A. Aluminium Casting Alloys with High Content of Zirconium. Proceedings of 5^th International Conference on Al-alloys and Their Physical and Mechanical Properties (ICAA5). Grenoble, France : Materials Science Forum, 1996. Vol. 217–222. pp. 293–298.
28. Lae L., Guyot P., Sigli C. Cluster dynamics in AlZr and AlSc alloys. Proceedings of ICAA9. Brisbane : Materials Science Forum, 2004. pp. 281–286.
29. Lyakishev N. P. Diagrams of the double metal systems state. Vol. 1. Moscow : Mashinostroenie, 1996. 996 p.