Sains Malaysiana 49(1)(2020): 179-188

http://dx.doi.org/10.17576/jsm-2020-4901-22

Kebolehbentukan-tikso Aloi 2014 dengan Penambahan Si dan Pengurangan Cu

(Thixoformability of 2014 Alloy with the Addition of Si and Decreasing of Cu)

M.A.M. ARIF*, M.Z. OMAR & Z. SAJURI

Centre for Materials Engineering and Smart Manufacturing (MERCU), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

Diserahkan: 11 Mei 2019/Diterima: 12 Oktober 2019

ABSTRAK

Dalam kajian ini, kebolehbentukan-tikso aloi aluminium (Al) 2014 dengan penambahan unsur silikon (Si) dan pengurangan unsur kuprum (Cu) dikaji. Kandungan Si dan Cu dalam aloi 2014 diubah suai supaya kriteria kebolehbentukan-tikso dapat dipenuhi. Kebolehbentukan-tikso aloi 2014 dan aloi Al-terubah suai diukur secara termodinamik dengan menggunakan pakej perisian JMatPro dan seterusnya dibuktikan secara uji kaji melalui analisis terma dan analisis fasa. Hasil kajian ini mendapati bahawa sifat kebolehbentukan-tikso aloi 2014 dapat dipenuhi dengan penambahan Si dan pengurangan Cu. Apabila kandungan Si dalam aloi 2014 bertambah, kandungan fasa eutektik pada titik 'lutut' tertinggi yang terbentuk di atas lengkung pecahan cecair meningkat dengan ketara, manakala julat suhu pemejalan pula semakin mengecil. Di samping itu, pengurangan Cu pula menyebabkan julat suhu pemprosesan untuk pembentukan-tikso menjadi semakin luas lalu mengakibatkan sensitiviti pecahan cecair pada titik 'lutut' tertinggi menurun. Selain pembentukan fasa Al₂Cu dan fasa θ-Al₅Cu₂Mg₈Si₆, kemunculan fasa π-Al₈FeMg₃Si₆ dengan struktur yang padat hasil daripada pengurangan Cu juga dijangka menyumbang kepada peningkatan sifat mekanik aloi Al-terubah suai. Akhir sekali, aloi Al-terubah suai tersebut dijangka mampu digunakan untuk menghasilkan komponen otomotif seperti rod penyambung, aci sesondol dan aci engkol melalui proses pembentukan-tikso. 

Kata kunci: Aloi aluminium; JMatPro; kebolehbentukan-tikso

ABSTRACT

In the present study, the thixoformability of aluminium (Al) alloy 2014 with the addition of silicon (Si) and the reduction of copper (Cu) was studied. The contents of Si and Cu in 2014 alloy were modified in order to fulfil the thixoformability criteria. The thixoformability of 2014 alloy and Al-modified alloy were measured thermodynamically using JMatPro software package and validated experimentally via thermal and phase analysis. The study found that the thixoformability behaviour of alloy 2014 had improved with the addition of Si and Cu reduction. When Si content in the alloy was increased, the amount of eutectic phase at the highest 'knee' on the liquid fraction curve increased significantly, while the solidification temperature range decreased. In addition, the reduction in Cu had increased the temperature range for thixoforming process and lowering the liquid fraction sensitivity at the highest 'knee'. In addition to the existence of Al₂Cu and θ-Al₅Cu₂Mg₈Si₆ phases, the emergence of π-Al₈FeMg₃Si₆ phase with compact structure resulting from Cu reduction is expected could be contribute to the improvement of the Al-modified alloy mechanical properties. Finally, the modified Al alloy is expected to be suitable to produce automotive components such as connecting rod, camshaft and crankshaft by using thixoforming process.

Keywords: Aluminium alloy; JMatPro; thixoformability

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*Pengarang untuk surat-menyurat; email: anifarif@gmail.com