Effect of microalloying with titanium on microstructure and mechanical properties of AZ91 magnesium alloy

Abstract

In the present investigation, the influence of minor Ti addition on the microstructure and mechanical properties of as cast AZ91 magnesium alloy was investigated. The results indicated that the microstructure of the AZ91 alloy with 0·4 wt-% Ti was mainly composed of α-Mg matrix and β-Mg₁₇Al₁₂ eutectic phases. After the addition of 0·4 wt-% Ti to the AZ91 alloy, the average grain size was obviously decreased and the microstructure was drastically refined. The morphology of the β-Mg₁₇Al₁₂ phases was mainly changed from the original partially divorced eutectics to the fully divorced eutectics. A significant enhancement of the tensile properties was found because of titanium addition.

Keywords:

• As cast magnesium alloys
• AZ91
• Titanium
• Mechanical properties

Acknowledgements

This work is supported by the National Natural Science Foundation of China (grant no. 50725413), the Ministry of Science and Technology of China (grant no. 2011BAE22B04), Chongqing Science and Technology Commission (grant no. CSTC2013JCYJC60001) and Doctoral Fund of Ministry of Education of China (grant no. 2013091110018). The authors are also grateful to Dr C. Y. Zhao, Dr H. Lin and Dr J. J. He for their valuable assistance in various aspects of the experimental programme.