Mirza F A, Chen D L
Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada.
Materials (Basel). 2015 Aug 10;8(8):5138-5153. doi: 10.3390/ma8085138.
Lightweighting in the transportation industry is today recognized as one of the most important strategies to improve fuel efficiency and reduce anthropogenic climate-changing, environment-damaging, and human death-causing emissions. However, the structural applications of lightweight alloys are often limited by some inherent deficiencies such as low stiffness, high wear rate and inferior strength. These properties could be effectively enhanced by the addition of stronger and stiffer reinforcements, especially nano-sized particles, into metal matrix to form composites. In most cases three common strengthening mechanisms (load-bearing effect, mismatch of coefficients of thermal expansion, and Orowan strengthening) have been considered to predict the yield strength of metal matrix nanocomposites (MMNCs). This study was aimed at developing a unified model by taking into account the matrix grain size and porosity (which is unavoidable in the materials processing such as casting and powder metallurgy) in the prediction of the yield strength of MMNCs. The Zener pinning effect of grain boundaries by the nano-sized particles has also been integrated. The model was validated using the experimental data of magnesium- and titanium-based nanocomposites containing different types of nano-sized particles (namely, Al₂O₃, Y₂O₃, and carbon nanotubes). The predicted results were observed to be in good agreement with the experimental data reported in the literature.
如今，交通运输行业的轻量化被认为是提高燃油效率以及减少人为造成气候变化、环境破坏和致人死亡排放的最重要策略之一。然而，轻质合金的结构应用常常受到一些固有缺陷的限制，比如刚度低、磨损率高以及强度较差。通过向金属基体中添加更强、更硬的增强材料，尤其是纳米尺寸颗粒，以形成复合材料，可以有效改善这些性能。在大多数情况下，三种常见的强化机制（承载效应、热膨胀系数不匹配以及奥罗万强化）已被用于预测金属基纳米复合材料（MMNCs）的屈服强度。本研究旨在通过在预测MMNCs屈服强度时考虑基体晶粒尺寸和孔隙率（这在铸造和粉末冶金等材料加工过程中是不可避免的）来建立一个统一模型。纳米尺寸颗粒对晶界的齐纳钉扎效应也被纳入其中。该模型利用含有不同类型纳米尺寸颗粒（即Al₂O₃、Y₂O₃和碳纳米管）的镁基和钛基纳米复合材料的实验数据进行了验证。观察到预测结果与文献报道的实验数据吻合良好。
