Sharif Digital Repository

In this study, Cu-TiC nanocomposites were produced by high energy ball milling of elemental powders and in situ formation of TiC in the copper base. Cu and 5,10,20 and 40 wt% Ti powder blend were milled for 60 h, then graphite powders were added and milling was continued for 10 h again and Finally Cu-TiC composite powders with 10.68, 20.16, 36.24 and 60.25 vol% of reinforcements (6.18, 12.2, 23.82 and 45.47 wt%) were produced. The effect of time on the solution of titanium in the copper was studied by X-Ray diffraction analysis (XRD). crystallite size and lattice strain of copper were determined 12nm and 1.04% subsequently for Cu-40wt%TiC after 60 h milling. to ensure the formation of... 

In this project formation of MgO & Mg2Cu reinforcement particle in Magnesium matrix was investigated. Firstly Mg & CuO powders mixture in different weight percentage (4, 8%wt CuO) in 20:1 and 30:1 BPR were milled. Finally, according to XRD result 30:1 BPR was selected for milling. Variations in powders morphology, particles size, crystallite size, lattice strain and phase transformation were investigated by X-ray diffraction, scanning electron microscopy and laser particle size analyzer in different milling time. Result showed that during reaction between Mg and CuO, MgO & Mg2Cu reinforcement particles were formed in matrix. Matrix crystallite size was determined about 35-40 nm. Mg-6.3%wt Cu... 

This research focused on mechanical properties of Al-TiB2 composite in as cast, heat treated and extruded condition. The composites were produced by mixing Al-Ti and Al-B master alloyes. Since some engineering parts during service are supposed to tolerate severe wear conditions, in this research abrasive wear condition was wxamined using pin on disk method. In a fixed load and abrasive disk, composites showed better resistance against wear in comparison with matrix alloy. Furtheremore, T6 heat treatment made composites more resistant against abrasive wear. Finally the best wear resistance was accompolished when composite was extruded and then heat treated. While increase in reinforcement... 

A study has been carried out on the formation of TiB2 particles in an aluminum based in-situ metal matrix composite by mixing master alloys containing Ti and B i.e., Al-10Ti and Al-8B with a Ti:B weight ratio of 5:2. It was shown that the microstructure of the composite was greatly affected by the controlling factors of the in-situ reaction like temperature, reaction time and stirring of the melt. An increasing reaction time leads to the dissolusion of the primary phases (AlB2 and Al3Ti) and the increase in TiB2 volume fraction. Optical microscope and SEM images were used to study these changes and XRD analysis was applied to confirm these observations. The act of melt stirring in short... 

For application such as electrical contacts and spot welding electrodes, both high electrical conductivity and wear resistance are required. Additionally, such parts should have structural stability at evaluated temperature. Copper based composites containing carbides or oxides reinforcement can be the good choice for production of such parts. In present work, in-situ Cu/NbC composite via mechanical alloying with homogenous distribution of nano reinforcement particle has been produced. For this purpose, in first stage, copper powder was milled with 5, 8, 10 and 12 wt. % of niobium powder in two types of mills, i. e. vibratory dicky mill and planetary ball mill for 5 and 32 h respectively. At... 

In this study, Aluminium based nanocomposite with Al3Ti and Al2O3 nanoparticles have been elaborated by mechanical alloying. For this purpose, Al and TiO2 powders have been blended with weight ratios of 10, 20 and 30 percents and were milled using a planetary mill. Morphological variations in different timing periods of mechanical milling process was investigated by Scaning Electron Microscopy (SEM) and The optimal times for alloying were determined for each combination. The pure Aluminium and the powder with 10, 20 and 30%wt reinforcement had coax morphology after respectively for 44, 30, 24 and 14 hours. after studing phase transformations by XRD analysis, the final powders were cold...