Among various mechanisms responsible for the strength-ductility trade-off in metallic materials, the leading strategy is to delay the onset of necking by improving the work hardening rate via a number of metallurgical approaches such as heterogeneous or gradient microstructures. Recent research activities on high-entropy alloys also witness a wide range of alloy design capabilities that permit these microstructural designs such as the dual-phase lamellar microstructures. This work addresses the contrasting strength-ductility behavior of equiaxed and lamellar microstructures when geometric features are the only tuning parameter. It is found that failures in lamellae are preceded by necking in the hard phase, the growth of which is significantly confined and suppressed by the surrounding soft phase. Detailed finite element simulations reveal various degrees of strength-ductility trade-off and synergy, which mainly depend on the microscopic processes that govern the delayed neck growth and ductile fracture. The upper limit of tensile ductility is theoretically believed to be determined by short-wavelength necking in the hard phase.

在造成金属材料强度-延展性折衷的各种机制中，主要策略是通过多种冶金方法（例如异质或梯度微结构）提高加工硬化率来延迟缩颈的发生。最近在高熵合金方面的研究活动还证明了广泛的合金设计能力，这些能力允许进行这些微结构设计，例如双相层状微结构。当几何特征是唯一的调整参数时，这项工作解决了等轴和层状微结构的对比强度-延性行为。已经发现，在薄层破坏之前，在硬相中出现颈缩，其生长明显受到周围软相的限制和抑制。详细的有限元模拟揭示了强度-延展性和协同作用的不同程度，这主要取决于控制延迟的颈部生长和延性断裂的微观过程。从理论上讲，拉伸延展性的上限由硬相中的短波长颈缩确定。