The gradient layered structure is beneficial to improve both strength and fracture toughness of tungsten. In this study, a series of W/(Ti/Ta/Ti) multilayer composites with gradient layered structure are prepared by field activated sintering technique (FAST) with bonding temperatures ranging from 1000 °C to 1400 °C. The results show that both the microstructure and mechanical properties vary with bonding temperatures. Both W and Ta diffuse into Ti layer to stabilize β phase, resulting in the Ti layer with α/β phase. The W/(Ti/Ta/Ti) composites bonded at 1200 °C exhibited the highest flexural strength (1700 MPa) attributed to excellent microstructure combination in the different layers, which are elongated grains and fine recrystallized grains in the W layer, and the martensite basketweave microstructure in Ti layer. Shear bands can be seen in the Ti layer with planar slip-bands and Ta layer with wavy slip-bands. These plastic deformation behaviors cannot be observed in the W layer because it is inherently brittle, similar to ceramic. The toughening mechanism of the W/(Ti/Ta/Ti) composites is as follows: crack deflection and delamination between the interface, multi-crack propagation in the W layer, and local shear deformation in the toughened layer. The bending properties of W/(Ti/Ta/Ti) multilayer composites are related to the interface and the gradient structure of the toughened layer (Ti/Ta/Ti), which can guide the design of the microstructure of the composites and improve its mechanical properties.

梯度层状结构有利于提高钨的强度和断裂韧性。在这项研究中，通过场激活烧结技术（FAST）制备了一系列具有梯度层状结构的W /（Ti / Ta / Ti）多层复合材料，其粘结温度范围为1000°C至1400°C。结果表明，微观结构和机械性能均随粘结温度而变化。W和Ta都扩散到Ti层中以稳定β相，导致Ti层具有α/β相。在1200°C下粘结的W /（Ti / Ta / Ti）复合材料表现出最高的抗弯强度（1700 MPa），这归因于不同层中优异的微观结构组合，这是W层中的拉长晶粒和细微再结晶晶粒，而Ti层中的马氏体网状组织。在带平滑带的Ti层和带波滑带的Ta层中可以看到剪切带。在W层中无法观察到这些塑性变形行为，因为它固有地易碎，类似于陶瓷。W /（Ti / Ta / Ti）复合材料的增韧机理如下：界面之间的裂纹偏转和分层，W层中的多裂纹扩展以及增韧层中的局部剪切变形。W /（Ti / Ta / Ti）多层复合材料的弯曲性能与增韧层（Ti / Ta / Ti）的界面和梯度结构有关，可以指导复合材料微观结构的设计并改善其微观结构。机械性能。在W层中无法观察到这些塑性变形行为，因为它固有地易碎，类似于陶瓷。W /（Ti / Ta / Ti）复合材料的增韧机理如下：界面之间的裂纹偏转和分层，W层中的多裂纹扩展以及增韧层中的局部剪切变形。W /（Ti / Ta / Ti）多层复合材料的弯曲性能与增韧层（Ti / Ta / Ti）的界面和梯度结构有关，可以指导复合材料微观结构的设计并改善其微观结构。机械性能。在W层中无法观察到这些塑性变形行为，因为它固有地易碎，类似于陶瓷。W /（Ti / Ta / Ti）复合材料的增韧机理如下：界面之间的裂纹偏转和分层，W层中的多裂纹扩展以及增韧层中的局部剪切变形。W /（Ti / Ta / Ti）多层复合材料的弯曲性能与增韧层（Ti / Ta / Ti）的界面和梯度结构有关，可以指导复合材料微观结构的设计并改善其微观结构。机械性能。