Effect of Cu and Cr addition on the structure, anticorrosion and nanomechanical properties of new Al-Ni-Fe-(Cr,Cu) alloys

This work used a thermodynamic approach to design and investigate new complex compositional Al-Ni-Fe-(Cr,Cu) alloys based on aluminum. This work tends to understand the change in microstructure during the rapid solidification process and to evaluate the anticorrosion and nanomechanical properties of the developed alloys. Optimizing thermodynamic parameters such as configurational entropy and Gibbs free energy was used to predict the chemical composition of the studied alloys. The samples were cooled in two ways. The ingots were slowly cooled, while the plates were cast using fast cooling by the high-pressure die-casting method. The presence of a quasicrystalline decagonal phase D-Al71Ni24Fe5 was identified together with crystalline Al3Ni, Al3Ni2, and Al9Ni1.3Fe0.7 phases for the rapidly solidified Al72Ni24Fe4 alloy. The best electrochemical parameters were observed for the Al72Ni24Fe2.5Cr1.5 alloy. The local galvanic microcells were formed in the studied alloys due to large potential differences (>50 mV) between the Al-Ni and Al-Ni-Fe phases. The highest average indentation hardness values were observed for Al72Ni24Fe4 (9.98 ± 1.75 GPa) after normal and rapid solidification. The higher ductility of the Al72Ni24Cr1.5Fe2.5 alloy compared to Al72Ni24Fe4 and Al72Ni24Cu1.5Fe2.5 could be confirmed by the lowest average hardness and Young's modulus values.