THERMAL STABILITY AND THERMAL EXPANSION BEHAVIOR OF AlFeCoNiCu AS-CAST HIGH-ENTROPY DUAL-PHASE ALLOY

Abstract

This work is devoted to the thermal stability and thermal expansion of dual-phase AlFeCoNiCu as-cast high-entropy alloy of equiatomic composition. The mix FCC + BCC phases is in AlFeCoNiCu high entropy alloy. According to characterized by EDS-analysis, Fe and Co are almost uniformly distributed in both phases in comparison with other elements. The BCC phase is rich in Ni and Al, and the FCC phase is Cu. Our measurement results of hardness and elastic modulus values for inter dendrites (FCC phase) and dendrites (BCC phase) of as-cast AlFeCoNiCu alloy showed the difference between there. Hardness values for inter dendrites and dendrites: 3.4±0.4GPa and 4.1±0.6GPa. Elastic modulus values for inter dendrites and dendrites: 130.5±2.0GPa and 166.5±5.6GPa. The thermal stability of the phases presented in AlFeCoNiCu as-cast high-entropy alloy has been studied with dilatometry and differential scanning calorimetry (DSC). The DSC thermogram shows an endothermic peak at 1000K. The coefficient of thermal expansion (CTE) curve shows linear increment from room temperature up to 1370K from (10.6 ± 0.3)×10^-6K⁻¹ to (27.7 ± 0.3) ×10^-6K⁻¹. The CTE temperature curve also shows the peak at 1000K. The peaks in the CTE temperature and the DSC curve suggest a phase transformation with increasing temperature up to~1000K.