铁/镍元素粉末的选区激光熔化过程扩散动力学研究

Diffusion Dynamic Analysis on Selective Laser Melting Process of Fe/Ni Powder

异质粉末3D打印,即采用纯元素或简单合金粉末混合进行3D打印,可以省略冶炼和制粉流程,在打印中直接完成冶金过程,相比传统基于均质金属粉末的3D打印,该法流程缩短、粉末种类减少,具有重要的发展价值。本文针对选区激光熔化(SLM)打印过程,提出了异质金属粉末直接3D打印冶金的技术原理,并以Fe基合金为例分析了各类元素的扩散动力学。计算表明,通过提高SLM脉冲峰值温度、延长熔态时长、减小合金粉末粒径、增加后续高温热处理等方法可以大幅提高打印过程中的元素扩散效率,实现成分均匀化。SEM和EDS实验结果显示,提高SLM脉冲峰值温度、延长熔态时长能有效提高扩散效率,与计算结果吻合。

Heterogeneous powder 3D printing technology uses mixed powder of pure element or simple alloy as raw material.It can omit the melting and milling process,complete the metallurgical process directly during printing.Compared with traditional 3D printing method,it can be one of the most important directions in the future as the production process is greatly shortened and the type of metal powder is dramatically reduced.This article proposed the technical principal on SLM process of heterogeneous metal powder.The feasibility of the technology was confirmed by diffusion simulation of Fe-based alloy systems during their molten state.The results show that the improvement of element diffusion efficiency and the composition homogenization can be achieved substantially by increasing the laser peak temperature,extending the melting time,reducing the size of metal powder and adding a subsequent high-temperature heat treatment.The results of SEM and EDS experiments show that the diffusion efficiency can be improved significantly by increasing the laser peak temperature and extending the melting time,which is consistent with the calcula-ted results.