Heterogeneous nucleation of β-type precipitates on nanoscale Zr-rich particles in a Mg-6Zn-0.5Cu-0.6Zr alloy
1 School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640, China
2 Australian Centre for Microscopy and Microanalysis, The University of Sydney, New South Wales, 2006, Australia
3 School of Mechanical Engineering, University of South China, Hengyang, 421001, China
4 Center of High Resolution Electron Microscopy, School of Materials Science and Engineering, Hunan University, Changsha, 410082, China
Nanoscale Research Letters 2012, 7:300 doi:10.1186/1556-276X-7-300Published: 8 June 2012
Zirconium (Zr) is an important alloying element to Mg-Zn-based alloy system. In this paper, we report the formation of the β-type precipitates on the nanoscale Zr-rich particles in a Mg-6Zn-0.5Cu-0.6Zr alloy during ageing at 180°C. Scanning transmission electron microscopy examinations revealed that the nanoscale Zr-rich α rods/laths are dominant in the Zr-rich core regions of the as-quenched sample after a solution treatment at 430°C. More significantly, these Zr-rich particles served as favourable sites for heterogeneous nucleation of the Zn-rich β-type phase during subsequent isothermal ageing at 180°C. This research provides a potential route to engineer precipitate microstructure for better strengthening effect in the Zr-containing Mg alloys.