J. Mater. Sci. Technol. ›› 2018, Vol. 34 ›› Issue (12): 2246-2255.DOI: 10.1016/j.jmst.2018.05.003

• Orginal Article • Previous Articles     Next Articles

Microstructure evolution, mechanical properties and diffusion behaviour of Mg-6Zn-2Gd-0.5Zr alloy during homogenization

Lei Xiao, Guangyu Yang*(), Yang Liu, Shifeng Luo, Wanqi Jie   

  1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
  • Received:2017-11-07 Revised:2017-12-19 Accepted:2018-02-08 Online:2018-12-20 Published:2018-11-15
  • Contact: Yang Guangyu

Abstract:

The microstructure evolution and mechanical properties of Mg-6Zn-2Gd-0.5Zr alloy during homogenization treatment were investigated. The as-cast alloy was found to be composed of dendritic primary α-Mg matrix, α-Mg + W (Mg3Zn3Gd2) eutectic along grain boundaries, and icosahedral quasicrystalline I (Mg3Zn6Gd) phase within α-Mg matrix. During homogenization process, α-Mg + W (Mg3Zn3Gd2) eutectic and I phase gradually dissolved into α-Mg matrix, while some rod-like rare earth hydrides (GdH2) formed within α-Mg matrix. Both the tensile yield strength and the elongation showed a similar tendency as a function of homogenization temperature and holding time. The optimized homogenization parameter was determined to be 505 °C for 16 h according to the microstructure evolution. Furthermore, the diffusion kinetics equation of the solute elements derived from the Gauss model was established to predict the segregation ratio of Gd element as a function of holding time, which was proved to be effective to evaluate the homogenization effect of the experimental alloy.

Key words: Mg alloy, Homogenization, Segregation, Diffusion kinetics