The enhancement of strength and ductility of titanium matrix composites (TMCs) is crucial for lightweighting and expanding their advanced engineering applications. However, it is still a challenge for TMCs to achieve ultrahigh tensile strength with suitable ductility. In this study, a special low-temperature accumulative hot rolling (AHR) process was proposed to regulate the grain/phase boundaries and dislocation structures of TMCs reinforced with networked TiB. Through the AHR process, we have achieved exceptionally tensile strength and yield strength of 1570 MPa and 1460 MPa, respectively, accompanied with a suitable ductility of ∼7.5 %. During the AHRed process, the majority of α-Ti grains rotated towards the favorable orientations, which display high SFs for basal slip in ND and prismatic slip in RD, respectively, resulting in the formation of {0002} texture. The accumulation and recovery of dislocations led to the formation of high-density sub-grain boundaries and geometrically necessary dislocations (GNDs) within α-Ti grains. Specifically, the GNDs rose dramatically from 1.06 × 1014 m−2 to 8.16 × 1014 m−2, whereas the size of α-Ti grains decreased significantly from 6.8 to 1.1 μm. In the β phase grains, secondary phase transformation was induced via the AHR process, resulting in the introduction of high-density nano-scaled secondary α-Ti lamellae (∼4 nm) with a fully coherent interface {110}BCC//{0002}HCP. After the AHR process, the crack nucleation and prolongation along the networked TiB was inhibited, resulting in the enhancement of ductility. This special AHR strategy, combining grain/hetero-phase boundary engineering and dislocation engineering, has great potential and universality for designing TMCs with both ultrahigh strength and suitable ductility.

中文翻译：

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通过核壳粉末的 SPS 烧结和累积热轧，实现网状 TiB 增强的钛基复合材料的高强度和延展性


钛基复合材料 （TMC） 的强度和延展性的增强对于轻量化和扩展其高级工程应用至关重要。然而，TMC 实现超高的抗拉强度和适当的延展性仍然是一个挑战。在本研究中，提出了一种特殊的低温累积热轧 （AHR） 工艺来调控网状 TiB 增强的 TMC 的晶粒/相边界和位错结构。通过 AHR 工艺，我们分别实现了 1570 MPa 和 1460 MPa 的异常抗拉强度和屈服强度，以及 ∼7.5% 的适当延展性。在 AHRed 过程中，大多数 α-Ti 晶粒向有利方向旋转，分别在 ND 和 RD 中表现出高基底滑移的高 SFs，从而形成{0002}织构。位错的积累和恢复导致 α-Ti 晶粒内形成高密度亚晶界和几何必要位错 （GND）。具体来说，GND 从 1.06 × 1014 m-2 急剧上升到 8.16 × 1014 m-2，而 α-Ti 晶粒的尺寸从 6.8 μm 显著减小到 1.1 μm。在β相晶粒中，通过 AHR 过程诱导二次相变，导致引入具有完全相干界面 {110}BCC//{0002}HCP 的高密度纳米级次级 α-Ti 薄片 （∼4 nm）。在 AHR 过程之后，沿网状 TiB 的裂纹成核和延长受到抑制，从而增强了延展性。这种特殊的 AHR 策略结合了晶粒/异相边界工程和位错工程，在设计具有超高强度和合适延展性的 TMC 方面具有巨大的潜力和普遍性。