Strain rate effect on the mechanical properties and microstructure of Al_xCr₃₀Fe₃₀Ni₂₀Ti_(20-x) high-entropy alloy

Al_xCr₃₀Fe₃₀Ni₂₀Ti_(20-x) (x = 10, 12, 14 at%) high-entropy alloys with varying Al and Ti contents were prepared to investigate the effects of the element composition on the phase structure, mechanical properties, and fracture morphology of the alloy. Quasi-static compression and dynamic impact tests were performed to examine the mechanical properties and fracture behaviors of the alloy under different strain rates. The results showed that all three alloys had dual-phase FCC/BCC structures. Among them, the Al₁₀Cr₃₀Fe₃₀Ni₂₀Ti₁₀ alloy exhibited the highest yield strength under both quasi-static and dynamic conditions. However, the Al₁₂Cr₃₀Fe₃₀Ni₂₀Ti₈ and Al₁₄Cr₃₀Fe₃₀Ni₂₀Ti₆ alloys showed better ductility. The fracture morphology observations revealed that all the alloys developed a fish-scale-like ductile dimple structure after quasi-static compression fracture. In contrast, under dynamic impact loading, the alloys formed tearing-type ductile dimples and cleavage planes, indicating a significant reduction in ductility at higher strain rates.