Titanium (Ti) alloy metal has been used for permanent implant in the human body. Its high strength and hardness take place due to the β phase formation at room temperature. Ti-6%Al-6%V alloy is most popular, of which vanadium (V) content is used as the β phase stabilizer. However V can induce allergic reaction from the body. V can be substituted by other element, such as Mo and Nb. Microstructure observations for Ti-6%Al-6%Mo and Ti-6%Al-6%Nb alloys show that β phase exists as matrix having good workability at room temperature. After preheat at 1000°C, no cracking failure occurs during forging and rolling treatment. Thermal spray method is used for CaPO4 surface treatment. A CaPO4 layer on the alloy substrate forms after the molten CaPO4 is hot sprayed on to the alloy substrate surface. Corrosion test results indicate that the increase in Mo or Nb content up to 6% leads to the increase in corrosion resistance.

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MgB2 superconductor is a superconductor with a critical temperature of around 39K and has the potential to replace Nb3Sn and NbTi as superconducting coils to produce high magnetic fields. In this study, monofilament wires have been made to analyze the doping effect of SiC and Carbon Nanotubes (CNT) in its manufacture using Powder-In-Tube (PIT) method. Stainless Steel (SS-316) tube was used as a tube filled with powders of starting materials of Mg, B, SiC and CNT. A total of 8 samples were prepared with variations in the addition of SiC, and CNT as much as 5, 10, and 15 wt %, and also the variations in the addition of Mg composition by 0 and 10 mol % from normal stoichiometric values. The samples were rolled and sintered at 800°C for 3 hours. The samples then were analyzed using SEM (Scanning Electron Microscopy) to analyze the surface morphology, XRD (X-Ray Diffractometer) to analyze the formed phases and crystal structures, and then resistivity versus temperature using cryogenic systems to analyze their superconductivity properties. Based on the results of the XRD analysis, the MgB2 phase is the major phase in the samples and the SiC doping causes the formation of minor phases of Mg2Si and Fe3C. The addition of SiC causes a decrease in crystalline properties of the MgB2 phase due to reaction with SiC, while the addition of CNT does not cause the formation of a new phase. Based on the results of the analysis of resistance versus temperature, it is seen that the addition of SiC causes a decrease in TC value. While the addition of CNT causes the improvement in the nature of superconductivity, but it also causes the decrease of its TC values.

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Titanium alloys are very interesting for biomedical applications due to excellent biocompatibility, corrosion resistance, lower density, and lower young modulus compared to cobalt and stainless steel alloys. However, compared to bone, young modulus of pure titanium and Ti-6Al-4V are still relatively high and the mechanical properties are still insufficient to meet the needs of biomaterials replacing the hard tissues. In this paper, a newly Ti-Mo-Nb based alloys were designed and the effect of Sn content in Ti-6Mo-6Nb-xSn alloys (x = 0,4,8 and 12 wt%) after homogenized on microstructure, hardness, and young modulus were investigated. The alloys were produced by electric vacuum arc furnace with non-consumable tungsten electrode then homogenized at 1100 °C for 7 under controlled argon atmosphere. Optical microscope, scanning electron microscopy, x-ray diffraction hardness test and ultrasonic test were used for alloys characterization. The results showed that Ti-6Mo-6Nb-xSn has equiaxed structure and Sn addition could promote the formation of β phase. The elasticity modulus of Ti-6Mo-6Nb-xSn alloy with the addition of 12% Sn was 88 GPa, this is better since it is below the elastic modulus of Ti6Al4V implant material.

Lateritic ore is one of the raw materials for the steel industry. Lateritic ore processed into laterite steel has more advantages than steel in the market. It has better tensile strength, hardness, corrosion resistance, and welding properties. Lateritic steel is made by performing a casting process. This research aims to investigate the effect of reduction percentage on mechanical properties and microstructure of the lateritic steel after the hot rolling process. The specimens were heated to austenitization temperature at 1000 0 C for 1 hour before the rolling process. The reduction percentage varies by 10%, 15%, and 20%. Hardness and impact test was conducted using a Rockwell Hardness and Charpy method. The microstructure was observed using an optical microscope. The results showed the optimum hardness of 58 HRC in a hot rolling sample with 20% reduction. The highest impact strength of 46 Joule and ductile fracture took place in this sample. The microstructure of this sample showed a bainitic phase causing lower hardness.

This research was aimed to do heat treatment of austemper carburization and investigate the effect of various cooling media on mechanical properties and microstructure of Cr-Mo alloy lateritic steel. Heat treatment was conducted to austenisation temperature at 950o C for 1 hour and austemper carburization at 400o C for 1 hour. Variation of cooling media included air blowing for 1 hour, water, and furnace cooling for 24 hours. Hardness and impact test were done using Hardness Rockwell and Charpy methods. Microstructure was observed using optical microscope. Fracture surface characterization was using SEM-EDX. The results showed the highest hardness of 65.48 HRC in sample that cooled by air blowing for 1 hour. The microstructure of this sample showed phases of ferrite, pearlite and martensite which causing higher hardness. The highest impact strength of 20 Joule took place in the furnace cooled sample. Characterization of the fracture surface using SEM-EDX showed dimple of ductile fractures.Penelitian ini bertujuan untuk melakukan proses perlakukan panas karburisasi austemper dan mempelajari pengaruh media pendinginan terhadap sifat mekanik dan struktur mikro baja laterit paduan Cr-Mo. Perlakuan panas yang dilakukan yaitu pemanasan sampel pada temperatur austenisasi (950o C) selama 1 jam dan proses karburisasi austemper dengan media serbuk arang halus pada temperatur 400o C selama 1 jam. Variasi pendinginan yang digunakan yaitu air blowing (semburan udara) selama 1 jam, air dan tungku selama 24 jam. Pengujian kekerasan dilakukan dengan metode Rockwell Hardness dan pengujian impak dilakukan dengan metode charpy. Karakterisasi struktur mikro dilakukan dengan proses metalografi dan mikroskop optik. Karakterisasi permukaan patahan pengujian impak dilakukan dengan SEM-EDX. Hasil penelitian ini menunjukkan nilai kekerasan tertinggi yaitu 65,48 HRC terjadi pada sampel dengan air blowing selama 1 jam. Struktur mikro sampel tersebut menunjukkan adanya fasa ferit, perlit dan martensit yang membuat sampel menjadi keras. Nilai kekuatan impak tertinggi sebesar 20 Joule terjadi pada sampel dengan pendinginan di dalam tungku selama 24 jam. Karakterisasi permukaan patahannya menggunakan SEM-EDX menunjukkan adanya dimple dari patah ulet.