M. Talebian, M. Alizadeh, M. Ehteshamzadeh,
Volume 33, Issue 2 (3-2015)
Abstract
In this study, Al/Steel multilayer composite was produced by accumulative roll bonding (ARB) process using Al-1100 and St-12 strips. Microstructure, mechanical properties and corrosion behavior of the composite were studied by scanning electron microscopy (SEM), tensile test, Vickers microhardness tests, cyclic polarization and electrochemical impedance spectroscopy (EIS) measurement in 3.5 wt% NaCl solution. After one ARB cycle (2 roll-bonding cycles), the multilayer composite of 4 layers of Al and 2 layers of steel was produced. The tensile strength of the Al/steel multilayer composite reached 390.57 MPa after the first ARB cycle, which was 1.29 times larger than that of the starting steel while composite density was almost half the density of the steel. Corrosion behavior of the composite revealed a considerable improvement in the main electrochemical parameters, as a result of enhancing influence of cold rolling. The results indicated that strength and corrosion resistance of Al/steel composite generally decreases and elongation increases after annealing.
A. R. Khanjani, A. Ghasemi,
Volume 35, Issue 2 (9-2016)
Abstract
In this study, nine Nd-Fe-B and FeCe thin films with 10-50 nanometers width were prepared by RF magnetron sputtering on the Si/SiO2 substrate. Then, the films were annealed at 800 oC for 5 sec in rapid thermal annealing furnace. X-ray diffractometry (XRD) was used to analyze the phase composition of layers and existance of Nd2F14 and Fe65Co35 phase was confirmed, without formation of any other secondary phase. The layers surfaces were investigated using Field Emission Scanning Electron Microscope (FESEM). The morphology of layers surfaces was investigated using Atomic Force Microscope (AFM). The magnetic properties of layers were evaluated by vibrating sample magnetometer with maximum applied field of 24kOe, in order to measure coercivity, saturation of magnetization, hysteresis area, rectangular ratio and (BH)max. It was found that all layers have vertical magnetic anisotropy. Increasing thickness of FeCo resulted in increasing saturation of magnetization, coercivity and saturation magnetization. The results indicate that by an increase in thickness of FeCo up to 20nm, exchange interaction strength between hard and soft magnetic layers is enhanced and, consequently, maximum energy induced from this hetero-structure is increased.
