Particulate-reinforced metal matrix composites (PRMMCs) are difficult to machine due to the inclusion of hard, brittle reinforcing particles. Existing experimental investigations rarely reveal the complex material removal mechanisms (MRMs) involved in the machining of PRMMCs. This paper develops a three-dimensional (3D) microstructure-based model for investigating the MRM and surface integrity of machined PRMMCs. To accurately mimic the actual microstructure of a PRMMC, polyhedrons were randomly distributed inside the matrix to represent irregular SiC particles. Particle fracture and matrix deformation and failure were taken into account. For the model’s capability comparison, a two-dimensional (2D) analysis was also conducted. Relevant cutting experiments showed that the established 3D model accurately predicted the material removal, chip morphology, machined surface finish, and cutting forces. It was found that the matrix-particle-tool interactions led to particle fractures, mainly in the primary shear and secondary deformation zones along the cutting path and beneath the machined surface. Particle fracture and dilodegment greatly influences the quality of a machined surface. It was also found that although a 2D model can reflect certain material removal features, its ability to predict microstructural variation is limited.

采用激光熔注技术在Ti-6Al-4V表面制备了ZrO_2p热障涂层,利用X-射线衍射、电子背散射衍射及扫描电镜技术,研究了激光熔注过程中ZrO₂颗粒的组织演变规律。结果表明:通过原子固态扩散,团聚态ZrO₂颗粒内的微粒尺寸增大,并由球状变为多面体状;激光熔注后,ZrO₂颗粒中未发现单斜相(m-ZrO₂);35%的稳定四方相(t'-ZrO₂)转变为立方相(c-ZrO₂);内应力降低,导致90%的正交相(o-ZrO₂)转变为c-ZrO₂。单个微粒内同时存在块状和纳米颗粒状t'-ZrO₂和c-ZrO₂,残留的o-ZrO₂集中分布于微粒界面。ZrO₂的组织演变使得微粒间的结合强度降低,促使ZrO₂大颗粒离散成细小颗粒,提高了涂层的防热性能。

对连续纤维增强铝基、镁基和钛基复合材料的制备方法、微结构与性能进行了综述，指出了存在的问题,提出了激光熔覆纤维增强金属基复合材料的新方法，即将纤维预置包埋在合金粉末中，然后进行快速激光熔覆。该方法能精确控制过程参数，大幅减少制备时间，可获得性能优异的复合材料。

采用激光熔注(LMI)技术在Ti-6Al-4V表面制备了WCp/Ti-6Al-4V梯度复合材料(MMC)层，对其形成机制进行了研究。研究结果表明，WC颗粒在复合材料层中的分布与其初始速度v0、穿越熔池表面最小临界速度vmin以及熔池粘度η有关。由于WC陶瓷颗粒密度大，在激光熔注过程中具有较高的动能，熔池粘度不再是决定梯度复合材料层形成的关键因素。对于WC/Ti材料体系，熔池凝固前沿是形成WCp/Ti-6Al-4V梯度复合材料层的重要因素，复合材料层不同深度范围内WC颗粒的数量由这一深度熔池凝固前沿长度所决定。WC颗粒注入位置对其在复合材料层中的分布有很大影响。在WC颗粒由熔池后部“拖尾”注入的情况下，该区域熔池深度较浅，WC颗粒遇到的熔池凝固前沿位于较高的位置，大多数WC颗粒被“冻结”在复合材料层的上部，进而形成了WCp/Ti-6Al-4V梯度复合材料层。

采用激光熔注(LMI)技术在Q235钢表面制备WC颗粒增强的金属基复合材料(MMC)层。在激光熔注工艺特性和熔注层宏观特征分析的基础上, 采用X射线衍射(XRD)和扫描电镜(SEM)对激光熔注层微观组织结构进行了分析。结果表明, WC颗粒注入到熔池的整个深度和宽度范围内, 并且在熔注层中的分布比较均匀。WC颗粒的加入改变了熔池的化学成分, 熔注层中出现了新相Fe3W3C。在熔注层上部存在较多Fe3W3C枝晶和少量枝晶间共晶, 在熔注层下部枝晶数量减少, 共晶数量明显增多。激光熔注层中不同WC颗粒周围反应层的尺寸和形貌存在很大差别。WC颗粒注入位置是决定反应层尺寸的重要因素。