The nacre-like (NL) structure exhibits unique performance in preventing the catastrophic crack growth and improving the strengthening/toughening of the overall structure. In this study, the In718/316LSS bimetallic NL structures were first fabricated by a powder laying-absorption multiple-material additive manufacturing technology based on laser powder-bed fusion, and the stress release mechanism was revealed. The NL structures with optimal geometric parameters was obtained by calculation and simulation: the hard-phase inclination angle of 15 °, the hard-phase volume fraction of 70%, and the lamellar length-width ratio of 2. Due to the remelting effect, the same-layer bimetallic interfaces in NL structures showed strong metallurgical bonding with significantly grain refinement. The interlocking NL structure exhibited superior mechanical properties of 751.82 MPa in tensile strength and 25.14% in elongation, compared with the base alloys and the non-interlocking NL structure. Moreover, abnormal variation of work hardening rate in NL structures attributed to the stress concentration and release behavior, caused by the multi-cracks initiation and cracks deflection during deformation of the interlocking structure. By the stress concentration-release effect, the NL structure not only achieved the strengthening and toughening, but also improved the crack tolerance to avoid the sudden fracture failure.

中文翻译：

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激光粉末床融合双金属珍珠质结构的结构设计、界面行为和机械性能

类珍珠质（NL）结构在防止灾难性裂纹扩展和提高整体结构的强化/增韧方面表现出独特的性能。本研究首次采用基于激光粉末床熔合的铺粉-吸收多材料增材制造技术制备了In718/316LSS双金属NL结构，并揭示了应力释放机制。通过计算和模拟得到了最佳几何参数的NL组织：硬质相倾角为15°，硬质相体积分数为70%，层状长宽比为2。由于重熔作用， NL结构中的同层双金属界面表现出强冶金结合，晶粒显着细化。与基体合金和非互锁NL结构相比，互锁NL结构表现出优异的机械性能，拉伸强度为751.82 MPa，伸长率为25.14%。此外，NL结构加工硬化率的异常变化归因于互锁结构变形过程中多裂纹萌生和裂纹偏转引起的应力集中和释放行为。通过应力集中-释放效应，NL结构不仅实现了强韧化，而且提高了裂纹容忍度，避免了突然断裂失效。