The Effect of Annealing Temperature on The Structure and Corrosion Behavior of Nano-Quasicrystalline Al72Ni13Cr15 alloy Synthesized by Mechanical Alloying

In the present effort, the nano quasicrystalline Al-Ni-Cr compounds were successfully synthesized by mechanical alloying and subsequent annealing and quenching. The effect of annealing temperature on the formation of crystalline and quasicrystalline phases was studied by an X-ray diffractometer and a scanning tunneling microscope. The crystallite size of quasicrystalline phase was investigated by high resolution transmission electron microscopy (HRTEM). Furthermore, the corrosion behavior of the produced compounds was evaluated by using 3-electrode potentiodynamic polarization test in both Na2SO4 1M and NaCl 3.5% solutions. It was found that, the structure of the compounds is affected significantly by the annealing temperature in which the quasicrystalline phase can only be created at considerably high annealing temperatures. Accordingly, the ternary ζ-phase (with hexagonal structure), two binary phases designated γ2 and δ (with rhombohedral and hexagonal structures, respectively) and D3 decagonal quasicrystalline phase were formed at 900 ̊C, 1000 ̊C and 1100 ̊C, respectively and it was observed that the nano-quasicrystalline phase developed. It was also found that, the quasicrystalline phase can be improved significantly the corrosion resistance of the produced samples in both NaCl and Na2SO4 solutions.