Study Of High Formability Of Glass Phase And Crystallization In Al-based Multicomponent Alloy

The material requires higher and higher as the development of the economy is so rapid.The Al-based amorphous alloy has many advantages,such as high strength and good ductility,and the strength can be further increased when nanometer-sized fcc-Al precipitates dispersedly in the amorphous matrix by partial crystallization,so Al-based amorphous alloy has good application prospect.However,low glass-forming ability considerably confines their practical applications.Therefore,to improve the GFA of Al-based amorphous alloys and further understand their crystallization behaviors becomes an urgent subject to be solved in materials science field.In this dissertation,the formation and crystallization behaviors of Al-Y-Ni-Co-Fe-Pd amorphous alloys were investigated by X-ray diffractometer?XRD?,differential scanning calorimetry?DSC?and other instyruments.The main results are as follows:multicomponent Al-Y-Ni-Co-Fe-Pd alloys were found to keep a mixed glassy+Al phases in the relatively large ribbon thickness range up to about200?m for the melt-spun ribbon and in the diameter range up to about 1100?m for the wedge-shape cone rod prepared by injection copper mold casting.The glass transition,followed by supercooled liquid region are observed for most Al-based alloys and the Al-based alloys has different crystallization processes,one is amorphous?fcc-Al+glass?Al+Al₃Y+Al₃Ni?Al+Al₃Y+Al₉?Co,Fe?₂+unknown phase and the other is glass transition,followed by supercooled liquid region,and then Al+cubic Al_xM_y?M=Y,Ni,Co,Fe,Pd?+Am?Al+Am?Al+Al₃Y+Al₉?Co,Ni?₂+unknown phase.In addition,it is noticed that the mixed Al and glassy phases are extended in a wide heating temperature range,and the Vickers hardness increases significantly to about 590 for the mixed Al and glassy phases though annealing which is favorable for the development of high-strength nanostructure Al-based bulk alloys.