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

Year 2019, Volume: 8 Issue: 2, 1143 - 1152, 31.07.2019

Huseyin Zengın

https://doi.org/10.28948/ngumuh.598092

Abstract

   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.

Keywords

Aluminum alloys, solidification, casting, microstructure, corrosion

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

Abstract

   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.

Keywords

Alüminyum alaşımları, katılaşma, döküm, mikroyapı, korozyon

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