Pengaruh Penambahan Nikel (Ni) Terhadap Sifat Kekerasan Dan Struktur Mikro Pada Paduan Aluminum–Silikon (Al-Si) Melalui Proses Pengecoran

Paduan Aluminum-Silikon ini memiliki sifat mekanik yang tinggi, ringan, kemampuan cor, dan ketahanan korosi. Penambahan Nikel dapat meningkatkan kekekerasan dan ketahanan korosi dari paduan aluminium-silikon (Al-Si). Salah satu aplikasi paduan Aluminium-Silikon-Nikel (Al-Si-Ni) adalah blok mesin. Pada penelitian ini, Aluminium-Silikon dengan komposisi Silikon 10,5% (Al-10,5Si) dipadukan dengan nikel sebesar 0,2 , 0,4 , 0,6 dan 0,8 % berat (%b). Proses pemaduan dilakukan melalui peleburan (pengecoran)di dalam tungku gas (gas furnace) pada temperatur 1450 oC dan waktu penahanan selama 1 jam. Paduan didinginkan secara lambat di dalam tungku gas (gasfurnace) hingga mencapai temperatur kamar. Pengujian yang digunakan dalam studi ini adalah spektroskopi dispersi energi sinar -X (EDS/EDX), Difraksi sinar X (XRD), pengujian sifat kekerasan (Hardness Test), dan Metalografi ( metallographic). Hasil pengujian EDS dan XRD menunjukkan terbentuknya paduan Al-Si-Ni. Sifat kekerasan paduan Al-Si-Ni menunjukkan peningkatan nilai kekerasan dengan meningkatnya penambahan Nikel. Pengamatan metalografi menunjukkan struktur mikro fasa Silikon Primer semakin kecil dengan penambahan Nikel. ========== Aluminum-Silicon alloys are said to have high mechanical, light-weight, cast-able, and resist corrosion characteristics. The addition of nickel could increase the hardness and corrosion resistance of an aluminum-silicon alloy (Al-Si). One of the uses of an Aluminum-Silicon-Nickel (Al-Si-Ni) alloy is engine block. In this research, Aluminum-Silicon with Silicon composition of 10,5%wt (Al-10,5Si) were alloyed with nickel varying at 0,2 , 0,4 ,0,6 and 0,8 % weight (%wt). The alloying process was conducted through smelting (casting) inside a gas furnace at 1450oC and held for an hour. The alloy was then slowly cooled down in the furnace until the temperature reached ambient temperature. Tests being conducted in this study were Energy Dispersive X-ray Spectroscopy (EDS/EDX), X-ray diffraction test, hardness test, and metallographic test.. The results of EDS and XRD tests showed that Al-Si- Ni alloy was formed. The hardness of Al-Si-Ni alloy showed improvement as the nickel increased. Metallographic observation indicated smaller silicon primer phase as the nickel’s amount increased