Effect of Samarium on the Microstructure and Corrosion Resistance of AZ91 Magnesium Alloy Treated by Ultrasonic Vibration

• Main Authors: Yang Chen, Zheng Yin, Hong Yan, Guo-Hua Zhou, Xiao-Quan Wu, Zhi Hu
• Format: Article
• Language: English
• Published: MDPI AG 2018-11-01
• Series: Materials
• Subjects: AZ91 magnesium alloy; Sm; microstructure; corrosion resistance; ultrasonic vibration
• Online Access: https://www.mdpi.com/1996-1944/11/11/2331

The effects of samarium (Sm) on the microstructure and corrosion behavior of AZ91 magnesium alloy treated by ultrasonic vibration were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and electrochemical measurements. The results showed that the addition of Sm resulted in the formation of Al₂Sm, which reduced the volume fraction of the β-Mg₁₇Al₁₂ phase and changed its morphology to fine granular. The AZ91⁻Sm alloys treated by ultrasonic vibration revealed relatively lower weight loss, hydrogen evolution, and corrosion current density values compared to the ultrasonic-treated AZ91 alloy prepared without Sm. Locally, a coarse β phase in the ultrasonic-treated AZ91 alloy accelerated the possibility of micro-galvanic corrosion growing into the matrix. In the prepared AZ91⁻Sm alloys treated by ultrasonic vibration, the fine β and Al₂Sm phases reduced the probability of micro-galvanic corrosion growth and, therefore, formed a uniform corrosion layer on the surface of the alloys.