Abstract: Laminated structures consisting of soft and hard components offer significant potential for enhancing the mechanical properties of metals. This study investigates the effect of hard component proportion (ranging from 6 % to 30 %) on the strength and toughness of laminated nanotwinned (LNT) Cu. The LNT Cu exhibits superior yield strength and effective crack growth threshold (ΔK_th,eff) compared to the rule-of-mixture (ROM) predictions, indicating additional strengthening and toughening. The extra strengthening increases monotonously as the hard component becomes more, resulting from the increasing strain gradient due to the weakening constraint between components. However, this weakened constraint disrupts the synchronous deformation of components during crack growth, causing cracks to advance preferentially in the hard component and an extra toughness peak in the sample with a hard component of 20 %. These findings provide valuable insights for optimizing laminated structures for enhanced mechanical performance.

Key words: Laminated nanotwinned, Component proportions, Toughening, Strengthening, Interface constraint