EFFECT OF SOLIDIFICATION RATE ON CORROSION RESISTANCE OF CAST Al-10Mg2Si IN-SITU COMPOSITES

Öz

   The hypoeutectic Al-10Mg₂Si (wt%) composites, also denoted as Al-6.3Mg-3.7Si (wt%) alloy, were cast in a steel step mould, in which different solidification rates were obtained. The microstructural characterizations were made by optical microscope and XRD. Corrosion performances were measured by immersion and electrochemical corrosion tests in 3.5% NaCl solution. Microstructure analysis showed that all the alloys consisted of a-Al, Chinese script type Mg₂Si and needle-like Al₅FeSi phases. Increasing solidification rate resulted in a remarkable refinement of Chinese script-like eutectic Mg₂Si phases. Corrosion tests revealed that increasing solidification rate improved the corrosion resistance of Al-10Mg₂Si composites due to the more uniform distribution of Mg₂Si phases and the stabilization of protective oxide films on the sample surface.

Anahtar Kelimeler

• Aluminum alloys,solidification,casting,microstructure,corrosion

DÖKÜM Al-10Mg2Si İN-SİTÜ KOMPOZİTLERİN KOROZYON DİRENCİNE KATILAŞMA HIZININ ETKİSİ

Öz

   Al-6.3Mg-3.7Si (ağ.%) alaşımı olarak da adlandırılan hipoötektik Al-10Mg2Si (ağ.%) kompozitleri, farklı katılaşma oranlarının elde edildiği bir kademeli çelik kalıba dökülmüştür. Mikroyapısal karakterizasyonlar optik mikroskop ve XRD ile yapılmıştır. Korozyon performansları %3.5 NaCl çözeltisinde daldırma ve elektrokimyasal korozyon testleri ile ölçülmüştür. Mikroyapı analizleri, tüm alaşımlarda a-Al, Çin yazısı şekilli Mg₂Si ve iğnemsi Al₅FeSi fazlarının oluştuğunu göstermiştir. Katılaşma hızındaki artış, Çin yazısı şekilli ötektik Mg₂Si fazlarının önemli derece küçülmesine neden olmuştur. Korozyon testleri sonucunda artan katılaşma hızının Al-10Mg₂Si kompozitlerinin korozyon direncini arttırdığı görülmüştür ve bu da Mg₂Si fazlarının daha düzgün dağılımı ve numune yüzeyindeki koruyucu oksit filmlerinin daha kararlı hale gelmesi ile meydana gelmiştir.

Anahtar Kelimeler

• Alüminyum alaşımları,katılaşma,döküm,mikroyapı,korozyon

Kaynakça

1. [1] OKAYASU, M., YOSHIDA, S., "Influence of solidification rate on material properties of cast aluminium alloys based on Al–Si–Cu and Al–Si–Mg", International Journal of Cast Metals Research, 28, 105–116, 2015.
2. [2] NORDIN, N.A., FARAHANY, S., ABU BAKAR, T.A., HAMZAH, E., OURDJINI, A., "Microstructure development, phase reaction characteristics and mechanical properties of a commercial Al–20%Mg2Si–xCe in situ composite solidified at a slow cooling rate", Journal of Alloys and Compounds, 650, 821–834, 2015.
3. [3] GHANDVAR, H., IDRIS, M.H., AHMAD, N., EMAMY, M., "Effect of gadolinium addition on microstructural evolution and solidification characteristics of Al-15%Mg2Si in-situ composite", Materials Characterization, 135, 57–70, 2018.
4. [4] NORDIN, N.A., FARAHANY, S., OURDJINI, A., ABU BAKAR, T.A., HAMZAH, E., "Refinement of Mg2Si reinforcement in a commercial Al–20%Mg2Si in-situ composite with bismuth, antimony and strontium", Materials Characterization, 86, 97–107, 2013.
5. [5] ZHANG, J., FAN, Z., WANG, Y., ZHOU, B., "Microstructural refinement in Al–Mg2Si in situ composites", Journal of Materials Science Letters, 18, 783–784, 1999.
6. [6] CHEN, L., WANG, H.Y., LI, Y.J., ZHA, M., JIANG, Q.C., "Morphology and size control of octahedral and cubic primary Mg2Si in an Mg–Si system by regulating Sr contents", CrystEngComm, 16, 448–454, 2013.
7. [7] WU, X.-F., WANG, Y., WANG, K.-Y., ZHAO, R.-D., WU, F.-F.," "Enhanced mechanical properties of hypoeutectic Al-10Mg2Si cast alloys by Bi addition", Journal of Alloys and Compounds, 767, 163–172, 2018.
8. [8] GUO, E.J., MA, B.X., WANG, L.P., "Modification of Mg2Si morphology in Mg–Si alloys with Bi", Journal of Materials Processing Technology, 206, 161–166, 2008.

9. [9] WANG, H., LIU, F., CHEN, L., ZHA, M., LIU, G., JIANG, Q., "The effect of Sb addition on microstructures and tensile properties of extruded Al–20Mg2Si–4Cu alloy", Materials Science and Engineering: A, 657, 331–338, 2016.
10. [10] JIANG, W., XU, X., ZHAO, Y., WANG, Z., WU, C., PAN, D., MENG, Z., "Effect of the addition of Sr modifier in different conditions on microstructure and mechanical properties of T6 treated Al-Mg2Si in-situ composite", Materials Science and Engineering: A, 721, 263–273, 2018.
11. [11] GHANDVAR, H., IDRIS, M.H., AHMAD, N., "Effect of hot extrusion on microstructural evolution and tensile properties of Al-15%Mg2Si-xGd in-situ composites", Journal of Alloys and Compounds, 751, 370–390, 2018.
12. [12] WANG, D., ZHANG, H., GUO, C., WU, H., CUI, J., "Effect of cooling rate on growth and transformation of primary Mg2Si in Al–Mg2Si in situ composites", Journal of Materials Research, 1–8, 2018.
13. [13] XU, C.L., WANG, H.Y., QIU, F., YANG, Y.F., JIANG, Q.C., "Cooling rate and microstructure of rapidly solidified Al–20wt.% Si alloy", Materials Science and Engineering: A, 417, 275–280, 2006.
14. [14] LI, S., ZHAO, S., PAN, M., ZHAO, D., CHEN, X., BARABASH, O.M., BARABASH, R.I., "Solidification and Structural Characteristics of α(Al)–Mg2Si Eutectic", Materials Transactions, 38, 553–559, 1997.
15. [15] AHLATCI, H., "Production and corrosion behaviours of the Al–12Si–XMg alloys containing in situ Mg2Si particles", Journal of Alloys and Compounds, 503, 122–126, 2010.
16. [16] FARAHANY, S., NORDIN, N.A., OURDJINI, A., ABU BAKAR, T., HAMZAH, E., IDRIS, M.H., HEKMAT-ARDAKAN, A., "The sequence of intermetallic formation and solidification pathway of an Al–13Mg–7Si–2Cu in-situ composite", Materials Characterization, 98, 119–129, 2014.
17. [17] KARANTZALIS, A.E., LEKATOU, A., GEORGATIS, E., POULAS, V., MAVROS, H., "Microstructural Observations in a Cast Al-Si-Cu/TiC Composite", Journal of Materials Engineering and Performance, 19, 585–590, 2010.
18. [18] SHABESTARI, S.G., "The effect of iron and manganese on the formation of intermetallic compounds in aluminum–silicon alloys", Materials Science and Engineering: A, 383, 289–298, 2004.
19. [19] MAKHLOUF, M.M., APELIAN, D., "Casting Characteristics of Aluminum Die Casting Alloys", Worcester Polytechnic Institute (US), 2002.
20. [20] BELMARES-PERALES, S., CASTRO-ROMÁN, M., HERRERA-TREJO, M., RAMÍREZ-VIDAURRI, L.E., "Effect of cooling rate and Fe/Mn weight ratio on volume fractions of α-AlFeSi and β-AlFeSi phases in Al−7.3Si−3.5Cu alloy", Metals and Materials International, 14, 307–314, 2008.
21. [21] SEIFEDDINE, S., JOHANSSON, S., SVENSSON, I.L., "The influence of cooling rate and manganese content on the β-Al5FeSi phase formation and mechanical properties of Al–Si-based alloys", Materials Science and Engineering: A, 490, 385–390, 2008.
22. [22] ZENGIN, H., TUREN, Y., AHLATCI, H., SUN, Y., "Mechanical Properties and Corrosion Behavior of As-Cast Mg-Zn-Zr-(La) Magnesium Alloys", Journal of Materials Engineering and Performance, 27, 389–397, 2018.
23. [23] ESCALERA-LOZAN, R., PECH-CANUL, M.I., PECH-CANUL, M.A., MONTOYA-DÁVILA, M., URIBE-SALAS, A., "The Role of Mg2Si in the Corrosion Behavior of Al-Si-Mg Alloys for Pressureless Infiltration", The Open Corrosion Journal, 3, 2010.
24. [24] SRINIVASAN, A., NINGSHEN, S., KAMACHI MUDALI, U., PILLAI, U.T.S., PAI, B.C., "Influence of Si and Sb additions on the corrosion behavior of AZ91 magnesium alloy", Intermetallics, 15, 1511–1517, 2007.
25. [25] KHARITONOV, D.S., DOBRYDEN, I.B., SEFER, B., ZHARSKII, I.M., CLAESSON, P.M., KURILO, I.I., "Corrosion of AD31 (AA6063) Alloy in Chloride-Containing Solutions", Protection of Metals and Physical Chemistry of Surfaces, 54, 291–300, 2018
26. [26] ÖZTÜRK, İ., HAPÇI AĞAOĞLU, G., ERZI, E., DISPINAR, D., ORHAN, G., "Effects of strontium addition on the microstructure and corrosion behavior of A356 aluminum alloy", Journal of Alloys and Compounds, 763, 384–391, 2018.
27. [27] ABDEL REHIM, S.S., HASSAN, H.H., AMIN, M.A., "Chronoamperometric studies of pitting corrosion of Al and (Al–Si) alloys by halide ions in neutral sulphate solutions", Corrosion Science, 46, 1921–1938, 2004.
28. [28] ARRABAL, R., MINGO, B., PARDO, A., MOHEDANO, M., MATYKINA, E., RODRÍGUEZ, I., "Pitting corrosion of rheocast A356 aluminium alloy in 3.5wt.% NaCl solution", Corrosion Science, 73, 342–355, 2013.
29. [29] LI, Z., LI, C., GAO, Z., LIU, Y., LIU, X., GUO, Q., YU, L., LI, H., "Corrosion behavior of Al–Mg2Si alloys with/without addition of Al–P master alloy", Materials Characterization, 110, 170–174, 2015. doi:10.1016/j.matchar.2015.10.028.
30. [30] ZENG, F., WEI, Z., LI, J., LI, C., TAN, X., ZHANG, Z., ZHENG Z., "Corrosion mechanism associated with Mg2Si and Si particles in Al–Mg–Si alloys", Transactions of Nonferrous Metals Society of China, 21, 2559–2567, 2011.