Deformation mechanism and resultant microstructural characteristics in extruded dilute Mg-0.1Bi-0.1Sn alloy with bimodal-sized grain structure under compression

Abstract

In this study, we examine in detail the hot deformation mechanism and dynamic recrystallization (DRX) behavior in a novel precipitate-free Mg-0.1Bi-0.1Sn alloy during hot compression conducted at 200–350 °C, with strain rate of 0.33–10 s−1. The obtained correlation coefficient is 0.98024, indicating that the present constitutive equation can adequately predict the hot deformation behavior of the studied alloy. The calculated average activation energy is 180.427 kJ/mol. According to the processing maps, the ideal processing areas correspond to the conditions of 325–350 °C/0.33–1 s−1. Under the low Z deformation condition, the basal slip dominates at the initial and later stages, while the pyramidal slip is dominate at the intermediate stage. Meanwhile, the continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) processes co-occur during hot compression. More specifically, in the initial stage, DDRX dominates over the DRX mechanism, and is accompanied by twinning induced dynamic recrystallization (TDRX). In the intermediate stage, CDRX, TDRX and DDRX prevail as the dominant DRX mechanisms. Throughout the strain stage, DDRX dominates over the DRX mechanism. The occurrence of TDRX and CDRX is beneficial to weakening the texture intensity and promoting the development of CD-tilted texture.

Keywords

• Dilute Mg alloy
• Hot compression
• Processing map
• Constitutive equation
• Dynamic recrystallization
• Texture