TC4钛合金表面激光熔覆CoCrNi基合金涂层的温度场模拟

利用COMSOL对TC4表面激光熔覆制备CoCrNiMox及CoCrNi(WC)x高熵合金涂层的熔化与凝固过程的温度场进行模拟，建立了三维多物理场并存的瞬态模型，同时考虑了传热、流体传热、对流以及表面熔覆层生长过程，分析对比了扫描速度、激光功率等参数对添加不同含量Mo及WC的CoCrNi基合金温度场的影响。通过模拟结果可以得知，激光熔覆过程中熔池的主要驱动力为马兰戈尼力，提高Mo含量时会使涂层温度场的最大值降低，但同时速度场和压力场的最大值会上升。此外，使用CoCrNiMo2作为涂层粉末相比于熔覆CoCrNi(WC)2，会在温度场、速度场和压力场均观察到较低的数值；激光功率逐渐升高，激光熔覆产生的熔池的中心温度也随之升高，且熔池的宽度、深度也将有所升高；扫描速度逐渐升高时，熔池中心最高温度显著降低，熔覆层起始位置明显推迟，熔覆层厚度明显减少，熔池的几何尺寸变小且熔池底部形貌对称性变差。

Temperature Field Simulation of High Entropy CoCrNi-based Alloy Coatings on TC4 Titanium Alloy Surface by Laser Cladding

Multi physics field simulation on the temperature field of two CoCrNiMox and CoCrNi(WC)x high entropy alloy coatings prepared by laser cladding on the TC4 surface was conducted by COMSOL. A three-dimensional transient model of multiple physical fields was established, while considering heat transfer, fluid heat transfer, convection, and surface cladding layer growth process. The effects of scanning speed, laser power, and other parameters on the temperature field of CoCrNi based alloys with different Mo and WC contents were analyzed and compared. Through simulation results, it can be concluded that the main driving force of the molten pool during laser cladding is the Marangoni force. For the same coating material, coatings with higher Mo content have lower maximum temperature fields, but higher maximum velocity and pressure fields. When the coating powder is different, the temperature field, velocity field, and pressure field formed by CoCrNiMo2 are all lower than those formed by melting CoCrNi(WC)2. As the laser power gradually increases, the center temperature of the molten pool generated by laser cladding also increases, and the width and depth of the molten pool will also increase. As the scanning speed gradually increases, the maximum temperature at the center of the melt pool significantly decreases, the starting position of the cladding layer is significantly delayed, the thickness of the cladding layer is significantly reduced, the geometric size of the melt pool becomes smaller, and the symmetry of the morphology at the bottom of the melt pool becomes worse.