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"Purpose of Research (specific objective and/or statement of hypothesis in around 300 to400 words. Please try to avoid using an additional page). Zry-4 is an alloy of Ziconium (Zr) with alloying elements of Fe,Cr, and Sn with weight percentage of 0.2%, 0.07% and 1.5% respectively. This alloying element addition is intended to improve the mechanical properties as well as Zirconium, that is corrosive resistance at high temperature. Besides the alloying elements, the micro structural morphology of Zry-4, as results of thermomechanic treatment process, also an active role to determine mechanical, physical and corrosion properties. This alloy is used as structure and cladding materials for Pressurized water Reactor (PWR) nuclear fuel element. Zirconium alloy of Zr-702 will also be used for chemical engineering devices due to its high corrosion resistance in acid and alkali liquid as well as at high temperature. Examples of device are : Distillation Column, Reactor, Pump Housing and Heat exchanger and Heating coil due to mechanical properties at high temperature. Some researchs have been done previously to observe changes of mechanical and corrosive properties of Zry-4 with solution treatment 0-phase, but unfortunately they are not continued between deformation degree and grain size with new precipitate is obtained.In this research we plan to carry out a cold deformation process of 0-quenching result and be continued with annealing process. From the process results we will observe the morphology of micro structure of Zry-4. This process will enable to determine the deformation level, time and temperature annealing to obtain a certain microstructure according to the desired mechanical properties (Microhardness). Results of research can hopefully be used as input in the working process of Zry-4.Optical Microscopy, Transmission Electron Microscopy and X-Ray Diffraction will be used in the microstructure observation."

"Pemanfaatan paduan aluminium untuk aplikasi otomotif telah dipertimbangkan karena faktor berat sehingga meningkatkan rasio power to weight dari motor penggerak dan ramah lingkungan. Penggunaan paduan aluminium juga diterapkan pada mesin nasional dua silinder dengan daya maksimum 11,5 kW/3.800 RPM. Efisiensi biaya dapat dicapai dengan peningkatkan yield dari produk cylinder head melalui modifikasi desain pengecoran dan perbaikan sifat mekanis pada daerah ruang bakar melalui penurunan nilai SDAS. Modifikasi casting design dilakukan melalui: pengubahan dimensi dan posisi dari chill dan riser, penggunaan "chill plate" pada daerah ruang bakar, dan penambahan titanium flux. Perangkat lunak simulasi pengecoran "Z-Cast versi 2.6" digunakan untuk membantu modifikasi casting design. Parameter simulasi dan percobaan pengecoran dilakukan pada temperatur tuang 690°C dan 730°C, material AC4B, material cetakannya pasir silika dan resin furan. Proses pengecoran, proses heat treatment T6, dan pengujian kualitas dilakukan sesuai dengan SOP yang sudah berlaku. Yield dari casting design awal dapat ditingkatkan lebih dari 16%. 0,15% berat Ti meningkatkan kekerasan pada permukaan bawah dan dome cylinder head baik pada kondisi pengecoran dan T6. Nilai SDAS lebih ditentukan oleh laju pembekuan yang ditunjukkan dengan penggunaan "chill plate". Peningkatan yield juga diikuti dengan penurunan biaya produksi hingga 7,11%.

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Utilization of aluminum alloys for automotive applications have been considered due weight factors which increased power to weight ratio of engine and environmental friendly. The use of aluminum alloys is also applied to the national two-cylinder engine with maximum power of 11.5 kW/3.800 RPM. Cost efficiency can be achieved by increasing product yield through the cylinder head casting design modifications and improving mechanical properties of the combustion chamber area through reduction of SDAS. Casting design modifications carried out through: changing the dimensions and position of the chills and the risers, using "chill plate" in the combustion chamber area, and adding titanium flux. Casting simulation software "Z-Cast version 2.6" was used to help casting design modifications. Parameters of simulation and experiments carried out at pouring temperatures 690 °C and 730 °C, AC4B ingot, silica sand and furan resin as mold material. The casting process, T6 heat treatment process, and quality testing conducted in accordance with SOPs that are applicable. Yield of the initial casting design can be increased more than 16%. 0,15 wt% of Ti increased the hardness at bottom surface and dome of the cylinder head in both ascast and as-T6. SDAS more determined by freezing rate which indicated by the use of "chill plate". Increased yield also accompanied by decrease in production costs of up to 7.11%."

"ABSTRAKMaterial badan pelindung kendaraan tempur umumnya terbuat dari baja yang memiliki kekerasan dan kekuatan impak yang tinggi. Namun karena densitasnya yang tinggi, dilakukan pengembangan material dengan densitas yang jauh lebih rendah namun tetap dapat menahan penetrasi peluru. Salah satunya adalah dengan mengembangkan metal matrix composite dengan matriks aluminium. Pada penelitian sebelumnya pelat komposit aluminium berpenguat SiC telah berhasil menahan peluru tipe III, namun masih mengalami retak dibagian belakang. Oleh karena itu, pada penelitian ini dilakukan penambahan unsur Ti dengan tujuan untuk meningkatkan ketangguhan matriks komposit melalui mekaisme penguatan batas butir.Komposit dengan matriks Al-11Zn-8Mg berpenguat 10 vol.% SiC dengan variasi kadar Ti sebesar 0, 0.018, 0.029, 0.224 wt.% difabrikasi menggunakan proses squeeze casting. Pelat komposit diberi laku pelarutan pada temperatur 450 oC selama 1 jam, dilanjutkan dengan laku penuaan pada temperatur 130 oC selama 102 jam untuk meningkatkan ketangguhannya. Karakterisasi yang dilakukan pada pelat komposit yaitu, pengujian komposisi kimia menggunakan Optical Emission Spetroscopy (OES), pengujian kekerasan menggunakan metode Rockwell B, pengujian impak menggunakan metode Charpy, pengamatan struktur mikro menggunakan mikroskop optik dan Scanning Electron Microscope (SEM) yang dilengkapi dengan Energy Dispersive X-Ray Spectroscopy (EDS).Hasil pengujian tersebut menunjukkan bahwa dengan peningkatan kadar Ti akan meningkatkan kekerasan pelat komposit melalui mekanisme penghalusan dendrit. Seiring dengan meningkatnya nilai kekerasan pelat komposit, harga impaknya menurun yang menunjukkan penurunan ketangguhan komposit. Penuaan meningkatkan kekerasan komposit secara signifikan dengan pembentukan endapan MgZn2. Adanya kandungan Ti menurunkan solute-vacancy-complexes sehingga menghambat mobilitas Mg dan Zn untuk membentuk presipitat.

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ABSTRACT

Materials for military vehicle are usually made of steel which has high hardness and high impact properties. Because of its high density, development of lighter materials with high hardness and high impact energy such as aluminium composites is done. Previous research has successfully produced SiC-strengthened aluminium composites that were able to withstand type III bullets, but cracks remained at the back of the plate. Therefore, in this research, Ti was added in order to increase the toughness of the composite matrix by grain boundary strengthening.

This research used Al-11Zn-8Mg as matrix and 10 vol.% SiC as reinforcement with Ti addition of 0, 0.018, 0.029 and 0.224 wt.% which were fabricated by squeeze casting method. The composites were solution treated at 450 oC for 1 hour, then aged at 130 oC for 102 hours. Material characterization consisted of chemical composition test by using Optical Emission Spectroscopy (OES), hardness test by using Rockwell B method and impact test using Charpy method, microstructural analysis by using optical microscope and Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS).

The results showed that addition of Ti increased the hardness by grain refining mechanism. The increase in hardness was followed by the decrease in toughness. The hardness significantly increased by aging process due to the formation of MgZn2 precipitates. Addition of Ti lowered the number of solute-vacancy-complexes which decreased the mobility of zinc and magnesium to form precipitate."