Sains Malaysiana 42(12)(2013): 1775–1780

Influence of Iron on Phase Stability and Corrosion Resistance of Ti-15%Cr Alloy

(Pengaruh Penambahan Besi terhadap Kestabilan Fasa dan Ketahanan Kakisan Aloi Ti-15%Cr)

JUNAIDI SYARIF*, EKO KURNIAWAN, ZAINUDDIN SAJURI & MOHD ZAIDI OMAR

Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Diserahkan: 23 April 2012/Diterima: 26 Jun 2012

ABSTRACT

In this study, the effect of Fe addition on the phase stability and corrosion resistance of Ti-15%Cr alloys was investigated. The alloying phenomenon in the specimens was also investigated to determine the effectiveness of the application of pure metallic powders as raw materials for the powder metallurgy method. Ti-15%Cr-1%Fe alloys exhibited needle-like structures within equiaxed structures, while Ti-15%Cr-5%Fe and Ti-15%Cr-10%Fe alloys only showed equiaxed grains. XRD results showed that the β phase could be stabilized by the addition of 5% or more Fe to the alloy. Although the pure powders were used as raw materials, the designated chemical composition, i.e. Ti-15%Cr-(1~10)%Fe can be achieved during sintering. The alloying phenomenon occurred upon sintering due to the high diffusivity of Cr and Fe within the β Ti matrix. The corrosion resistance of the newly developed Ti-15%Cr alloys was significantly improved compared with a commercial Ti-6%Al-4%V alloy.

Keywords: Alloying phenomenon; β phase; corrosion resistance; powder metallurgy; sintering

ABSTRAK

Dalam kajian ini, kesan penambahan Fe terhadap kestabilan fasa dan rintangan kakisan pada aloi Ti-15%Cr dikaji. Fenomena pengaloian di dalam spesimen juga telah dikaji untuk menjelaskan keberkesanan penggunaan serbuk logam tulen sebagai bahan mentah untuk kaedah metalurgi serbuk. Aloi Ti-15%Cr-1%Fe mempamerkan struktur seperti jarum di dalam struktur sama paksi. Sebaliknya, aloi Ti-15%Cr-5%Fe dan aloi Ti-15%Cr-10%Fe hanya menunjukkan ira sama paksi sahaja. Hasil XRD menunjukkan bahawa fasaβ akan menjadi lebih stabil dengan penambahan Fe lebih besar daripada 5%. Spesimen boleh mencapai komposisi kimia yang ditetapkan iaitu Ti-15% Cr (1 ~ 10)% Fe selepas proses pembuatan dilakukan, meskipun kajian ini menggunakan serbuk logam tulen. Fenomena pengaloian berlaku pada masa pensinteran kerana kadar peresapan Cr dan Fe pada matriksβ-Ti adalah tinggi. Aloi Ti-15%Cr-Fe juga dikaji dan hasil kajian menunjukkan bahawa ketahanan kakisan aloi tersebut mengalami peningkatan berbanding dengan ketahanan kakisan aloi Ti-6Al-4V yang merupakan aloi komersial.

Kata kunci: Fasaβ; fenomena pengaloian; ketahanan kakisan; metalurgi serbuk; persinteran

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*Pengarang untuk surat-menyurat; email: syarif@eng.ukm.my