Journal of Advanced Materials in Engineering (Esteghlal)

In this study, microstructure and mechanical properties of diffusion joints between 5754, 6061 and 7039 aluminum alloys and AZ31 magnesium alloy were investigated. Diffusion joints were done between the alloys at 440 °C, for duration of 60minutes, at 29 MPa pressure and under 1×10^-4 torr vacuum. The interface of joints was studied using optical (OM) and scanning electron microscopy (SEM) equipped with EDS analysis and the line scan. According to the results of EDS analysis, the presence of intermetallic compounds including Al₁₂Mg₁₇, Al₃Mg₂ and their mixture was observed at the diffusion zone. Also, according to the results of the line scan, the hardness value of aluminum alloys has a considerable effect on diffusion of the magnesium atoms toward aluminum alloy and the greatest diffusion of magnesium was observed when 6061 aluminum alloy was used. More diffusion resulted in a stronger bond between atoms of magnesium and aluminum, and maximum strength of approximately 42 MPa was obtained when 6061 aluminum alloy was used.

In this research, investigation of the microstructure and magnetic properties of doped barium hexaferrite with cobalt, chromium and tin with BaCo_xCr_xSn_xFe_12-3xO₁₉ (x=0.3,0.5) formula, was performed using solid state method. Phase and structural investigation by X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy respectively, confirmed the formation of barium hexaferrites single phase without the presence of non-magnetic secondary phase after heat treatment for 5 h at temperature of 1000 °C. Also, according to scanning electron microscopy (SEM) images, morphology of particles was perfectly hexagonal with average particle size 200-250 nm. Based on magnetic parameters measured by Vibrating Sample Magnetometer (VSM), both samples were soft magnetic and the highest saturation magnetization was obtained for the sample with composition of BaCo_0.3Cr_0.3Sn_0.3Fe_11.1O₁₉. The values of saturation magnetization (M_s) and the coercivity (H_c) were 42.21 emu/g and 656 Oe respectively for this compound.

In this study, the effect of Fe/Ba molar ratio was investigated on the phase composition, synthesis temperature, microstructure and magnetic properties of barium hexaferrite prepared via mechanical activation. In order to synthesize this compound, Fe/Ba molar ratios of 12 and 6 were used. The effect of Fe/Ba molar ratio, milling time and heat treatment temperature for achieving the optimal conditions in producing this compound was studied. In order to study the phase, morphology and magnetic properties of the final product, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) were used respectively. According to the results, Fe/Ba molar ratio of 6, 10 h milling time and temperature of 800 °C were found to be the optimal conditions for producing this compound in a single phase. Scanning electron microscopy images show the hexagonal morphology and almost spherical particles respectively for samples prepared with Fe/Ba molar ratio equal to 12 and 6. Moreover, according to the magnetic studies, the maximum amount of saturation magnetization (56.48 emu/g) and the coercivity force (5247.2 Oe) were obtained for the sample synthesized with Fe/Ba molar ratio of 6.