Effect of Al on the microstructure and high temperature oxidationperformance of Cu-20Ni-19Fe alloy

Abstract

In order to solve the problem of poor oxidation resistance of Cu-Ni-Fe inert anode at high temperature during aluminum electrolysis,Cu-20Ni-19Fe-xAl alloys (x=0%,6%,8%,10%) with different Al contents were prepared by vacuum melting method,and the alloys were used for the high temperature oxidation experiments which were carried out at 850 ℃ with oxygen partial pressure of 1.013×105 </sup>Pa and oxidation time of 100 h,and the effects of Al addition on the microstructure and high temperature oxidation properties of the alloy were investigated.The results show that the as-cast Cu-20Ni-19Fe alloy is composed of Ni/Fe-rich dendritic phase (γ1) and Cu/Ni-rich matrix phase (γ2);Al was dissolved in the Cu-20Ni-19Fe alloy matrix with 6% content of Al added;The needle-like or blocky NiAl phase was formed in the microstructure of Cu-20Ni-19Fe alloy with 8% and 10% Al added;The content of NiAl phase increases with the increasing addition of Al;The oxidation kinetics of Cu-20Ni-19Fe alloy follow the straight line under 850 ℃ and oxygen partial pressure of 1.013×105</sup> Pa;After the addition of Al,the oxidation kinetic curve of Cu-20Ni-19Fe-xAl alloy follow an exponential law,and the oxidation rate index of the Cu-20Ni-19Fe-xAl alloy was much smaller with more content of Al.The high-temperature oxidation resistance of Cu-20Ni-19Fe alloy was greatly improved by the addition of Al,which proves the Cu-20Ni-19Fe alloy may be used as an alternative anode material for aluminum electrolysis.

Keywords

• nonferrous metals and their alloys; cu-ni-fe alloy; microstructure; high temperature oxidation; aluminium electrolysis