Ultrasonic characterization of recrystallized microstructure evolution for Al_0.26CoCrFeNiMn high-entropy alloys

Abstract

Al0.26CoCrFeNiMn high-entropy alloys were prepared by vacuum induction melting and casting method, and processed by homogenized annealing, rolling and recrystallized annealing. The microstructure evolution of the alloys during thermomechanical treatment was investigated based on ultrasonic method. The results show that the microstructure is coarse equiaxed grain after homogenized annealing, retaining deformed grain when recrystallized annealing temperature is 800℃, forming fine equiaxed grain when recrystallization is completed at 900℃, and then the grain grows at 1000℃.Besides, the grain size decreases with the increase of rolling ratio at the same recrystallized annealing temperature. At the aspect of ultrasonic characterization, the attenuation coefficient for probe testing with nominal frequency of 5MHz increases with the increase of grain size, and the attenuation coefficient with average grain size is corresponded in a cubic relationship, having a strong correlation. In order to further verify the feasibility of the method, the probe with nominal frequency of 7.5MHz was used to test, and the similar correlation was acquired. The attenuation coefficient can reveal the microstructure evolution of high-entropy alloys during thermomechanical treatment, especially for the relationship between grain size and thermomechanical treatment process.

Keywords

• high-entropy alloy
• rolling
• recrystallization
• grain
• ultrasonic attenuation coefficient