激光熔覆NbC 颗粒复合镍基非晶涂层结构调控及其强韧化机理

针对镍基非晶涂层硬度相对较低、裂纹敏感性高等问题，提出通过激光熔覆技术制备具有优异力学和摩擦学性能的NbC颗粒相增强镍基非晶复合表面涂层。研究内容和目标为：利用混合焓、归一化错配熵及深共晶等非晶形成理论并结合激光熔覆技术特点设计和优化镍基合金体系的成分比例范围，并进行高压氩气雾化粉末制备；借助数值模拟和熔池动态实时观测，重点突破激光熔覆参数对瞬时微区熔体流动特性、凝固行为对NbC颗粒相分布的影响，实现涂层微结构的有效调控，设计和构筑出具有协同增强微、纳摩擦效应的非晶复合涂层；以非晶剪切带与NbC颗粒相之间的交互作用行为为切入点，揭示颗粒/基体协调变形与细观损伤演化之间的规律，探讨非晶复合涂层的强韧化机制；研究涂层相组成、微结构与摩擦学性能之间的关联，建立颗粒复合非晶涂层的抗磨机制和物理模型。预期成果将为颗粒增强非晶涂层的激光制备及其在关键机械部件上的应用提供理论依据和技术储备。

The relatively low microhardness and high cracks sensitivity are two important factors gauging the performance of Ni-based amorphous coating. In this study, NbC particles are introduced to deposit high mechanical and wear resistance properties Ni-based amorphous composite coating on mild steel substrate by laser cladding process. The study details and aims are: The calculated mixing enthalpy and mismatch entropy, deep eutectic theory and experimental results are used to design and optimize the Ni-based alloy system composition. Then, the powders are fabricated by high pressure atomization process. With the helping of numerical simulation and melted pool real time observation, the effects of process parameters on flow characteristics, solidification behavior and NbC particles distribution are studied to accurately control the coating microstructure. In order to design and build a synergistic strengthened amorphous composite coating with micro, nano-wear effect. The interaction between shear-bands and NbC particles are studied to learn the rule of particle/matrix compatible deformation and meso-damage evolution. Then the strengthening and toughening model of the coating is build. Finally, the correlation among phase, microstructure and wear resistance tests is conducted to study the wear resistance mechanisms and its physical model. The findings of the project can provide theory evidence and technical guidance for the fabrication of particles strengthened amorphous composite coating using laser processing and its application in key mechanical components.