The interfacial binding interactions in fiber–reinforced metal matrix nanocomposites (MMNC) are involved with sophisticated physico-chemical​ phenomena that are sensitive to their commonly encountered high-temperature processing and/or working environments. The resulting interfacial load transfer characteristics, which play a vital role in achieving the anticipated bulk mechanical properties enhancements, remain elusive. Here we investigate the effect of thermal processing on the interfacial strength of carbon nanotube (CNT) reinforced titanium (Ti) nanocomposites by conducting in situ nanomechanical single-nanotube pull-out measurements inside a high resolution scanning electron microscope. Our nanomechanical measurements reveal that thermal annealing at 400 °C for two hours results in a 40% decrease of the interfacial load-carrying capacity. The measurements were analyzed using a micromechanics shear-lag model, and the results show that the thermal annealing reduces the maximum interfacial shear strength by about 42% from about 231MPa to about 135 MPa. The observed weakening of the CNT–Ti interface caused by thermal annealing is attributed to the formation of newly grown titanium oxide on the CNT–Ti binding interface. The findings reported here are useful to better understand the impact of thermal processing on the reinforcing efficiency of nanotubes in metal matrices, which is essential to the design and manufacturing of nanotube-reinforced MMNC with superior high-temperature performance.

纤维增强金属基质纳米复合材料（MMNC）中的界面结合相互作用涉及复杂的物理化学现象，这些现象对其常见的高温加工和/或工作环境敏感。所产生的界面载荷传递特性在实现预期的整体机械性能增强方面起着至关重要的作用，目前仍难以捉摸。在这里，我们通过原位传导研究热处理对碳纳米管（CNT）增强的钛（Ti）纳米复合材料界面强度的影响高分辨率扫描电子显微镜内的纳米机械单纳米管拉出测量。我们的纳米力学测量表明，在400°C下进行两个小时的热退火会使界面承载能力降低40％。使用微力学剪切滞后模型对测量进行了分析，结果表明，热退火将最大界面剪切强度从约231MPa降低到约135 MPa，降低了约42％。观察到的由热退火引起的CNT-Ti界面的减弱归因于CNT-Ti结合界面上新生成的氧化钛的形成。此处报道的发现有助于更好地了解热处理对金属基体中纳米管增强效率的影响，