Local structure and stability of amorphous CuFeZr alloys

The local structure and stability of amorphous Cu_{60 − x}Fe_xZr₄₀ were investigated by Mössbauer effect and differential scanning calorimetry measurements. The isomer shift decreased with increasing iron concentration for x < 5 and increased for x > 5. The activation energy of crystallization was 5.5–5.8 eV for x < 5 and decreased abruptly with increasing x for x > 5. These results show that copper atoms around an iron atom are substituted by iron atoms for x < 5 and that zirconium atoms around an iron atom are also substituted by iron atoms for x > 5. From the comparison of Mössbauer spectrum parameters for amorphous Cu₅₉Fe₁Zr₄₀ and crystallized Cu₅₉Fe₁Zr₄₀, it was shown that the average local structure of amorphous Cu₅₉Fe₁Zr₄₀ is similar to that of crystallized Cu₅₉Fe₁Zr₄₀ but that the former is more asymmetric than the latter. It was suggested that the asymmetry in local structure and the interatomic spacing are concerned with the stability of amorphous structure.