Influence of small calcium additives on the structure and properties of ML5 (AZ91) alloy
https://doi.org/10.17073/0021-3438-2016-3-65-74
Abstract
The influence of calcium additives (from 0,1 to 1,0 wt.%) on the phase composition and the solidus temperature of ML5 magnesium alloy was studied. During the alloy crystallization in the presence of aluminum, calcium forms an intermetallic compound with a variable composition containing Al (53,4–57,4 %), Ca (42,6–42,8 %) and Mg (0,002–3,8 %). As the temperature decreases, this compound degenerates to Al2Ca combination. The impact of calcium on the number of Mg17Al12 and Al2Ca phases as well as its distribution in the structure of the cast and heat-treated ML5 alloy was analyzed. By means of the electron microprobe analysis, it was found that calcium and aluminum were concentrated along the boundaries of the solid magnesium solution. It was shown that satisfactory mechanical properties of magnesium alloys containing calcium could only be acquired by their smelting and casting according to the process preventing metal contamination with rough inclusions. It was found that small calcium additions (up to 1 wt.%) increased combustion temperature and reduced the oxidation of the alloy at elevated temperatures (up to 715 °C). The effect of sulfur hexafluoride on the loss of calcium in flux-free melting was found.
About the Authors
I. V. Plisetskaya
National University of Science and Technology «MISIS» (NITU «MISIS»), 119049, Russia, Moscow, Leninsky pr., 4
Russian Federation
Russian Federation
Cand. Sci. (Tech.), engineer, Department of foundry technologies and material art working (FT&MAW), NITU «MISIS»
A. V. Koltygin
National University of Science and Technology «MISIS» (NITU «MISIS»), 119049, Russia, Moscow, Leninsky pr., 4
Russian Federation
Russian Federation
Cand. Sci. (Tech.), associate professor, Department of FT&MAW, NITU «MISIS»
References
1. Rokhlin L.L. Aktual’nye problemy v oblasti primeneniya magnievykh splavov [Current problems in the application of magnesium alloys]. Tsvetnye metally. 2006. No. 5. P.62—66.
2. Rokhlin L.L. Budushchee magniya i magnievykh splavov [Future of magnesium and magnesium alloys]. Tekhnologiya legkikh splavov. 2004. No. 3. P. 55—60.
3. Hossein Bayani, Ehsan Saebnoori. Effect of rare earth elements addition on thermal fatigue behaviors of AZ91 magnesium alloy. J. Rare Earths. 2009. Vol. 2. No. 27. P. 255—258.
4. Rzychoń T., Kiełbus A. Effect of rare earth elements on the microstructure of Mg—Al alloys. J. Achiev. Mater. Manufact. Eng. 2006. No. 17. P. 149—152.
5. Moreno I.P., Nandy T.K., Jones J.W., Allison J.E., Pollock T.M. Microstructural stability and creep of rareearth containing magnesium alloys. Scr. Mater. 2003. No. 48. P. 1029—1034.
6. Alan A. Luo. Magnesium casting technology for structural applications. J. Magn. Alloys. 2013. No. 1. P. 2—22.
7. Fan Jianfeng, Yang Changlin, Xu Bingshe. Effect of Ca and Y additions on oxidation behavior of magnesium alloys at high temperatures. J. Rare Earths. 2012. No. 30. P. 497— 502.
8. Cheng Su-ling, Yang Gen-cang, Fan Jian-feng, Li You-jie, Zhou Yao-he. Effect of Ca and Y additions on oxidation behavior of AZ91 alloy at elevated temperatures. Trans. Nonferr. Met. Soc. China. 2009. No. 19. P. 299—304.
9. Cho J., Kim R., Lee K.-W., Son Ch. Low-voltage characteristics of MgO—CaO films as s protective layer for AC plasma display panels by e-beam vaporation. J. Mater. Sci. 1999. No. 34. P. 5055—5059.
10. Polmear A.S. Legkie splavy ot traditsionnykh do nanokristallov [Light alloys from traditional to nanocrystals]. Moscow: Prosveshchenie, 2009. P. 264—327.
11. Kondori B., Mahmudi R. Effect of Ca additions on the microstructure, thermal stability and mechanical properties of a cast AM60 magnesium alloy. Mater. Sci. Eng. A. 2010. No. 527. P. 2014—2021.
12. Chukhrov M.V. Modifitsirovanie magnievykh splavov [Modification of magnesium alloys]. Moscow: Metallurgiya, 1972. P. 16—17.
13. Ravi Kumar N.V., Blandin J.J., Suery M., Grosjean E. Effect of alloying elements on the ignition resistance of magnesium alloys. Scr. Mater. 2003. No. 49. P. 225—230.
14. You B.-S., Park W.-W., Chung I.-S. The effect of calcium additions on the oxidation behavior in magnesium alloys. Scr. Mater. 2000. No. 42. P. 1089—1094.
15. Aljarraha M., Medraj M., Wang X., Essadiqi E., Muntasar A., Denes G. Experimental investigation of the MgAlCa system. J. Alloys Compd. 2007. No. 436. P. 131—141.
16. Cao H., Zhang C., Zhu J., Cao G., Kou S., Schmid-Fetzer R., Chang Y.A. A computational/directional solidification method to establish saddle points on the Mg—Al—Ca liquidus. Scr. Mater. 2008. No. 58. P. 397—400.
17. Manping Liu, Qudong Wang, Zili Liu, Guangyin Yuan, Guohua Wu,Yanping Zhu, Wenjiang Ding. Behavior of Mg—Al—Ca alloy during solution heat treatment at 415 °С. J. Mater. Sci. Lett. 2002. No. 21. P. 1281—1283.
18. Koltygin A.V., Plisetskaya I.V. O povedenii kal’tsiya v liteinykh magnievykh splavakh sistemy Mg—Al—Zn—Mn [The behavior of calcium in casting magnesium alloys of the Mg—Al—Zn—Mn]. Liteinoe proizvodstvo. 2010. No. 8. P.2—6.
19. Koltygin A.V., Bazlova T.A., Plisetskaya I.V. Vliyanie kal’tsiya na protsess polucheniya i strukturu magniya, vyplavlennogo v usloviyakh besflyusovoi plavki [Effect of calcium on the process of production and structure of magnesium melted by f lux-free method]. Metallovedenie i termicheskaya obrabotka metallov. 2012. No. 10(688). P.50—54.
20. Koltygin A.V., Plisetskaya I.V. Perspektivy razvitiya magnievykh liteinykh splavov, svyazannye s primeneniem kal’tsiya v kachestve legiruyushchei dobavki [Development prospects of magnesium casting alloys connected with application of calcium as an alloying element]. Liteishchik Rossii. 2012. No. 1. P. 38—41.
Review
For citations:
Plisetskaya I.V., Koltygin A.V. Influence of small calcium additives on the structure and properties of ML5 (AZ91) alloy. Izvestiya. Non-Ferrous Metallurgy. 2016;(3):65-74. (In Russ.) https://doi.org/10.17073/0021-3438-2016-3-65-74
Views:
1002
Email this article 