Authors: Jenő Gubicza, Magdy Kassem, Tamás Ungár
Abstract: The effect of the nominal Mg content and the milling time on the microstructure of mechanically alloyed Al(Mg) solid solutions is studied. The crystallite size distribution and the dislocation structure are determined by X-ray diffraction peak profile analysis. Magnesium gradually goes into solid solution during ball milling and after 3 h almost all of the Mg atoms are soluted into the Al matrix. With increasing milling time the Mg content in solid solution, the dislocation density as well as the hardness are increasing, whereas the crystallite size is decreasing. A similar tendency of these parameters is observed at a particular duration of ball milling with increasing of the nominal Mg content. At the same time for a long milling period the dislocation density slightly decreases together with a slight reduction of the hardness.
103
Authors: Taha Rostamzadeh, H. Shahverdi, R. Sarraf-Mamoory, A. Shanaghi
Abstract: Mechanical alloying is one of the most successful methods for the manufacturing of metal matrix nanocomposite powders. In this study, Al/SiC metal matrix composite (MMCp) powders with volume fractions of 5, 10, and 15 percent SiC were successfully obtained after milling the powder for a period of 25 hours at a ball to powder ratio of 15:1 using high energy planetary milling. The Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were conducted to investigate the lattice strain of the matrix phase and the microstructure of the nanocomposite powders after 1, 10, and 25 hours of milling time. Also, the morphology of the Al-5%SiC nanocomposite powder was investigated using transmission electron microscopy (TEM). The results show that with the increase of both milling time and the reinforcement phase volume fraction, the lattice strain increases and the average size of aluminum phase crystallites decreases. Eventually, after 25 hours of milling, the nanocomposite powders show a spherical-like morphology and SiC particles were distributed in an aluminum matrix with appropriate order.
764
Authors: H. Kaffash, Ali Shokuhfar, Hamid Reza Rezaie, Ehsan Mostaed, Ali Mostaed
Abstract: Fabrication of alloys in the solid state via mechanical alloying (MA) process has been studied by earlier researchers. The effects of milling time and impact force, defined as the ball-to-powder weight ratio (BPR), on the elemental diffusion during synthesis of nanostructured Fe-50at.%Cu alloy via MA process were evaluated in the current work. X-ray diffraction patterns revealed that increasing the milling time and impact force give rise to increasing the micro-strain, lattice parameter and decreasing the crystallite size during the MA process. Furthermore, scanning electron microscopy (SEM) was utilized not only for evaluating the microstructure of the milled powder particles but also for proving this claim that during MA process, the mutual diffusion of Cu and Fe has occurred. The interpretation of data resulted have been discussed in details.
1262
Authors: Traian Florin Marinca, Ionel Chicinaş, Virgiliu Călin Prică, Florin Popa
Abstract: Nanocrystalline nickel ferrite powder was obtained using high energy reactive ball milling technique. Nickel oxide (NiO) and iron oxide (Fe2O3) powders were used as starting material. Milling was performed in air atmosphere using a planetary ball mill. Milling time was up to 30 hours. The product of milling was annealed at 350 oC for 4 hours in order to eliminate the internal stresses and finish the solid state reaction. X-ray diffraction analysis was used to study the nickel ferrite formation. A nanocrystallite mean size of 10 nm was found after 24 hours of milling. Using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDX) the particle morphology and the chemical homogeneity were studied. It was found that the obtained product has particle size in range of micron and submicron.
145
Authors: Claudinei dos Santos, Alexandre Fernandes Habibe, Durval Rodrigues, José C. Minatti, Jefferson F.C. Lins, Luis Alberto dos Santos
Abstract: In this study, the effect of ball/powder ratios for grinding particles of a dental alloy consisting of 66%Co-28%Cr-6%Mo was investigated. Metal powders were obtained from SPEX mill, with tungsten carbide balls, setting the milling time to 60 minutes, 50% of volume of grinding vessel filled with powder and argon inert atmosphere. The ball/powder ratio was varied between 4:1, 6:1, 8:1, 10:1.The powders were characterized by XRD indicating Co as only crystalline phase present, which indicates that Cr and Mo enter into solid solution with the matrix Co. Measurement of crystallite size conducted using the Scherrer equation indicate the crystallite size about 10 to 6nm, due to the increase of the ball/powder ratio of 4:1 to 10:1. The morphology of the milled powders were analyzed by scanning electron microscopy (SEM) and indicate that the agglomerates created by the grinding process must have average sizes varying between 100μm and 200μm with the modification of the ball/powder.
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