Quantitatively regulated and recognized dual-precipitates of Mg-5Sn alloy through an improved twinning-aging-detwinning and strengthening mechanisms

Abstract

The orientation of precipitates was regulated by an improved twinning-aging-detwinning (TAD) process in Mg-Sn sheets. A structure with specific proportions of dual-precipitates was regulated, significantly enhancing the material's strength. The formation mechanism of the dual-precipitates was investigated, and the evolution of precipitate orientation was confirmed. A combined SEM, EBSD and TEM method was developed to identify the coupling relationship between complex grain orientation and precipitate orientation. The orientation relationship between precipitates and the matrix could be quantitatively analyzed in the same region. Subsequently, the Orowan model was refined to quantify the strength enhancement effect following the orientation regulation of precipitates. The TAD sample containing dual-precipitates exhibited a 99.1 % increase in TYS, equivalent to an increase of 108 MPa, compared to unregulated samples A. According to Orowan calculations, the theoretical strength increment from the three strengthening mechanisms was 113 MPa, closely matching the experimental increment of 108 MPa. Notably, the materials with a specific proportion of the dual-precipitates showed a substantial increase in strength.