Synchronous improvement in mechanical properties and corrosion resistance of Mg-Gd-Ag-Zr alloy through nanoprecipitates
Bangjun Li, Jiapeng Sun, An Xu, Bingqian Xu, Lingling Wang, Jie Yuan, Guosong Wu
Abstract
It is still challenging to synchronously improve mechanical properties and corrosion resistance through one strategy during developing Mg alloys. Introducing high-density precipitates is an effective and popular approach to strengthen Mg alloys, while these precipitates generally degrade the corrosion resistance. In this paper, the nanoprecipitates are developed in Mg-13.4Gd-2.2Ag-0.4Zr wt.% cast alloy through the solution and aging treatment for evading this dilemma. Compared with its as-cast counterpart, the peak-aged alloy with high-density nanoprecipitates exhibits enhanced strength, comparable ductility, and improved corrosion resistance. The nanoprecipitates in the peak-aged alloy are composed of β nanoparticles at grain boundaries, and intragranular γ′′ and β′ nanoplates. These nanoprecipitates are contributed to the improved strength through the Orowan mechanism. The β nanoparticles induce weak galvanic corrosion, and the γ′′ nanoplates have not induced visible galvanic corrosion, thus contributing to the enhanced corrosion resistance of the peak-aged alloy. This result suggests that developing nanoprecipitate is a feasible route to collaboratively optimize the mechanical and corrosion properties of the Mg alloys.