Crystallization, mechanical and electrochemical behavior of Al-Ce-TM (TM = Fe, Co, Ni and Cu) amorphous alloys

Abstract

Al86Ce10TM4 amorphous alloys (TM=Fe, Co, Ni and Cu) were fabricated using melt-spin fast-quenching method. 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 Tx1 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 Tx2 associated with activation energy E2 and frequency factor Ko2 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 (860~1180 MPa), corrosion resistance (10-8A/cm2 ) and high temperature endurance (284, 300 and 420°C for Al86Ce10Co4 , Al86Ce10Ni4 andAl86Ce10Fe4 , respectively) compared to hardness 500~600 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.