Effect Of High Magnetic Field On The Crystallization Of Al-Y-Fe Amorphous Alloys

Al-based amorphous alloys containing≥85at.%Al and transition metals and rareearth elements have attracted much attention due to a combination of high specificstrength and good ductility. These excellent mechanical properties make this new familyof Al-based amorphous alloys well studied for using as an advanced engineeringmaterials candidate for industrial application. Till now, the Al-based amorphous alloyswere prepared normally in the form of either thin ribbons or powders, since the synthesisof these glassy alloys requires high cooling rates from melts. Furthermore, thecrystallization temperature of Al-rich glassy alloy is mostly lower than250℃. The lowthermal stability against crystallization further restricts their application. Thereforeimprove the glass formation ability of Al-based alloy is to be solved currently, andanalysis its thermal stability also has important significance.This study mainly analysis the effect of high magnetic field on crystallization andthermal stability of Al-based amorphous alloy, The influence of high magnetic fielddiffusion of solute elements. Al-Y-Fe alloy ribbons were prepared by melt spinning. Thestructures of as-quenched ribbons were characterized by X-ray diffraction (XRD) andtransmission electron microscope (TEM), and the glass transition and crystallizationbehavior of the alloys were analyzed with differential scanning calorimeter (DSC).Al88Y5Fe7amorphous alloys were isothermal annealing at different temperature in steadymagnetic field, and the structures of samples after annealing were characterized by XRDand TEM.The results show that the as-quenched Al88Y6Fe6, Al84Y7Fe7, Al89Y5Fe6, Al88Y5Fe7ribbons are fully amorphous. High magnetic field reduces the thermal stability ofAl88Y5Fe7amorphous alloy, meanwhile high magnetic field may reduce the thermalstability of unidentified phase（2θ=21.5°）, which lead to precipitate under high magneticfield at280℃environment and no precipitation phase without magnetic field. However,the unidentified phase will vanish under the circumstance of high magnetic field at370℃,and precipitated phase will happen without magnetic field at370℃. The precipitatedphase of Al88Y5Fe7amorphous alloy becomes Nano-sized block of aluminum crystalsannealed at280℃for30min. It evenly distributed on amorphous matrix. The effect of high magnetic field on amount of precipitation, size and distribution of Al nanoparticlesis not distinct, and Al grain growth and formation of intermetallics occur at370℃. Inaddition, high magnetic field have important influence on the diffusion of soluteelements. Each interplanar distance of Al crystal under high magnetic field at280℃becomes smaller than without magnetic field, but under high magnetic field at370℃, itleads to the contrary results.