Research On Crystallization Behavior And Properties Of Amorphous Aluminum Alloy

The speed of science-developing becomes faster and faster,people have been exploring space.The emergence of aerospace industry has also led to the vigorous development of the field of materials.It’s necessary for people to invent excellent materials which possess the performance of high strength,low quality,high toughness and good corrosion resistance.The amorphous alloy stands out for its excellent mechanical properties,and the aluminum based amorphous alloy is the leader.Aluminum based amorphous alloy fascinated researchers to expand it since it was first prepared by predecki due to its low cost and high performance.However,the disadvantage is that Al based amorphous alloys can not be prepared in large scale like other amorphous alloys,which is still an unsolved problem in the development of Al based amorphous alloys.In this paper,Al₈₆Ce₁₀TM₄ amorphous alloy（TM=Fe,Co,Ni and Cu）is used as the research object.The sample thin strip is made by melt spin rapid quenching method,and all the flat surfaces are smooth after polishing.The amorphous state of the sample was detected by XRD and TEM,The crystallization,mechanical and electrochemical behavior of the as-spun and the post-annealed alloys were investigated by X-ray diffraction（XRD）,differential scanning calorimetry（DSC）,micro-indentation and electrochemical techniques.It was found the completely amorphous Al₈₆Ce₁₀TM₄ alloys（TM=Fe,Co,Ni and Cu）go through two crystallization processes,where the first exothermal peak represents nucleation of nano-crystalline particles and the second exothermal peak signifies growth of the nano-crystalline precipitates.Both the nucleation and growth processes rely on diffusion-controlled mechanism.The first onset crystallization temperature T_x11 associated with activation energy E₁ and frequency factor Ko1 can be used to evaluate the thermal stability of the amorphous alloys while the second onset crystallization temperature T_x22 associated with activation energy E₂ and frequency factor K₀₂2 can be taken to judge the thermal stability of ideal amorphous-nanocrystalline mixed structure in sustaining optimized mechanical and electrochemical properties.The as-spun and post-annealed alloys exhibit higher mechanical hardness（860¹180 MPa）,corrosion resistance(10^-8A/cm²)and high temperature endurance(284,300 and 420°C for Al₈₆Ce₁₀Co₄,Al₈₆Ce₁₀Ni₄ andAl₈₆Ce₁₀Fe₄,respectively)compared to hardness 500⁶00 MPa,corrosion resistance 10^-7A/cm² and high temperature durability 200°C of traditional Al crystalline alloys,manifesting the value on scientific studies and engineering applications of the Al₈₆Ce₁₀TM₄ amorphous alloys.Finally,it is found that annealing in the range between the first and second initial temperatures plays an important role in the manufacture of ideal amorphous nanocrystalline hybrid structure,which not only has the best mechanical hardness,but also has the best corrosion resistance,that is to say,the composite structure has the same or even higher performance compared with the complete amorphous structure.