A synergetic approach to nullify tension to compression yield asymmetry of Mg matrix composite by in-situ TiB2 reinforcement and microstructural modification

Abstract

Designing heterogeneous microstructure is a promising way to overcome the tensile/compressive yield asymmetry in light weight Magnesium metal matrix composites (Mg MMCs) for load bearing capabilities. Herein, we have adopted an innovative strategy to engineer TiB2 reinforced ZE41 matrix composite with varying microstructural features, including uniformly dispersed sub-micron sized in-situ TiB2 reinforcements, β-phase, rare-earth content T precipitates and equiaxed grain structures. This leads to prominent strength and ductility with negligible yield asymmetry in TiB2/ZE41 (1.06) as compared to unreinforced ZE41(1.38). The suppression of {10–12} extension twinning mode of deformation due to the back stress imposed by the simultaneous action of in-situ TiB2 particles and precipitates almost nullifies the yield asymmetry in TiB2/ZE41 composite. Further, the scientific knowhow on yield asymmetry behavior of ZE41 Mg alloy with/without in-situ TiB2 particles and precipitates have been established via understanding the dominant twinning mechanism, strain hardening behavior under tension and compression, Schmid factor, and {10–12} twinning interaction with particles and/or precipitates.