论文部分内容阅读
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。
The WCp / Ti-6Al-4V gradient composite (MMC) layer was prepared on the surface of Ti-6Al-4V by LMI, and its formation mechanism was studied. The results show that the distribution of WC particles in the composite layer is related to the initial velocity v0, the minimum critical velocity vmin passing through the weld pool and the viscosity η of the weld pool. Due to the high density of WC ceramic particles, high kinetic energy in the laser melting process, the viscosity of the weld pool is no longer the key factor that determines the formation of the gradient composite material layer. For the WC / Ti material system, the solidification front of the weld pool is an important factor for the formation of the WCp / Ti-6Al-4V gradient composite layer. The number of WC particles in different depths of the composite layer is determined by the length of the solidification front . The WC particle injection location has a great influence on its distribution in the composite layer. In the case of WC particles implanted from the rear of the bath, the depth of the bath is shallower, the front of the pool solidification encountered by the WC particles is located at a higher position, and most of the WC particles are “frozen ”In the upper part of the composite layer, and then formed WCp / Ti-6Al-4V gradient composite layer.