Nano-scale precipitation and phase growth in Mg-Gd binary alloy: An atomic-scale investigation using HAADF-STEM

作者：Zheng, Jingxu Kent; Luo, Ruichun; Zeng, Xiaoqin; Chen, Bin^*

来源：Materials and Design, 2018, 137: 316-324.

DOI：10.1016/j.matdes.2017.10.042

• Rare earth-containing Mg alloys
• Precipitation
• Age hardening
• High angle annular dark field

In the present study, nanoscale precipitation and phase growth in Mg-15Gd(wt%) binary alloy are comprehensively studied by atomic-resolution high angle annular dark field -scanning transmission electron microscopy (HAADF-STEM). Various nanoscale precipitate structures, including beta(H), beta, beta(T)', beta(M) and beta''-like structure, assembled by the "basic unit" as building block, are observed, reconstructed and discussed in detail. In the early stage of precipitation, the precipitate growth basically follows y (nm) = 1.53x-2.68 (nm) and protrusions start to grow when the size of a precipitate reaches a threshold value. Long-range diffusion of Gd solute preferentially proceeds along < 1010 > Mg directions and protrusions are formed. A large number of fine beta' precipitates exist and act as the key strengthening structures. The formation of precipitate-free zones in the over-age condition is attributed to the intertwining of precipitates.

• 出版日期2018-1-5
• 单位上海交通大学