Texture-related strength-ductility trade-off in Mg alloys: New insights from an accurate and efficient semi-analytical relaxed constraint model

A novel semi-analytical model combining relaxed constraint theory and the Sachs hypothesis was proposed to describe the plastic deformation of magnesium (Mg) alloys. The model stands out by its ability to efficiently and accurately calculate the strength-ductility of Mg alloys influenced by texture using a constitutive equation. The proposed model effectively captures the changes in tensile flow curves during the weakening process from strong basal to fiber texture. It explains how divergence weakening promotes twinning and inhibits slip, leading to reduced yield strength and increased uniform elongation. The strength-ductility relationship for the two main texture adjustment methods, divergence and deviation, is shown to vary with adjustment angles. The model emphasizes that non-basal slip dominance during early deformation significantly enhances strength, while twinning contributes the least. Conversely, basal slip dominance is optimal for improving ductility, whereas non-basal slip proves the least effective. By adjusting model parameters, the impact of alloying on strength-ductility trade-off is evaluated, revealing that reducing the activation differences in deformation mechanisms can improve the overall material performance. These findings provide valuable insights for optimizing process design to achieve a balanced strength and ductility in Mg alloys. • Developed a microstructure-based constitutive model using single-slip RC. • Modified the semi-analytical model with Hall-Petch and Voce hardening. • Introduced Schmid factor evolution in the modified model for enhanced prediction. • Semi-HVM-RC clarifies strength-ductility relation across texture adjustment angles. • Alloying effects with reduced activation gaps improve strength-ductility balance.