ABSTRAK
Pada industri hot chamber diecasting pengunaan scrap bekas gating danproses machining pengunaanya tidak secara optimal untuk didaur ulang agar bisamenjadi raw material . Hal ini dikarenakan adanya unsur pengotor besi yang ikutterlarut kedalam paduan Zn-Al dan membentuk fasa intermetalik yang terlihatpada strukturmikro . Fenomena ini akan mengakibatkan terjadinya cacat danpenurunan sifat mekanisPenelitian ini bertujuan mengetahui pengaruh penambahan modifier Al-5TiB sebagai grain refiner merubah morfologi fasa intermetalik sehinggameningkatkan fluiditas dan kekuatan mekanis dari paduan seng . Untukmengetahui penyebab itu dilakukan penelitian dan pengujian meliputi pengecekankomposisi kimia, fluiditas , pengujian sifat mekanis , pengamatan struktur mikrodengan SEM & EDAX.Dari hasil penelitian ini menunjukkan pengaruh dari pengotor melaluipenambahaan kadar besi (Fe) 0.04% dan 0.19% yang dapat mengakibatkanpeningkatan fraksi fasa intermetalik pada batas butir yang menyebabkanpenurunan kekuatan tarik, impak dan fluiditas pada paduan Zamak 3.Penambahaan grain refiner Al-5TiB dengan 0.5% dan 1% pada master alloyZamak 3 dengan kandungan besi (Fe) 0.19% dapat membuktikan peningkatansifat mekanis dan nilai fluiditas . Akibat terbentuknya fasa intermetalik yangterdistribusi seragam dibatas butir yang lebih halus dapat terlihat dari hasilpengamatan mikrostruktur.

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ABSTRACT
Zamak 3 is one of the many zinc alluminium alloys, as a raw material inthe manufacturing industry with diverse product applications. This alloy has agood combination of mechanical properties, castability, and good dimensionalstability. Therefore, the manufacturing is able to do with the method of die castingwith the production on a mass scale and shape precision. In casting industry, scrapleft over from casting results have not been optimal product use. This is becausethere is an element of excess impurities and reduce castability. Iron (Fe) elementis the element contained impurities that reduce the ability of mechanical andfluidity.As a result of these problems, the research carried out by utilizing thecomposition and nature of the scrap is given modifier to reduce the negativeinfluence of impurity elements are present. This study aims to determine the scrapoptimization with the addition of grain refiner Al-5TiB. Through variation of theaddition of 0.5% and 1%, this study will examine the intermetallic morphologyphase of alloy structure, influence on the mechanical properties and fluidity withvacuum testing. Refined grains will reduce the influence of intermetallic that isbecause the element Fe.The results showed that addition of Fe 0,04% and 0,19% (above standard0,002%) can lead the increasing of intermetallic phases fraction at grainboundaries by microstructure analysis. Therefore, this intermetallic cause adecrease in mechanical properties and fluidity.The modification by added Al-5TiB to the alloy trigger the formation of a new phase with a subtle formintermetallic phase and prove an increase in the mechanical properties andfluidity. It is also a major effect on the value of the fluidity and mechanicalproperties of the alloy. Thus, we can conclude how much influence the grainrefiner in distributing the intermetalic phase as seen in microstructure.