为了研究W-Ni-Cu合金选区激光熔化技术(SLM)直接成形工艺及其热物理性能, 设计了以激光功率、扫描速度、扫描线长度、搭接率为变量的工艺实验, 研究各参数对致密度的影响, 采用SEM、热分析仪、差式扫描量热仪、热-机械分析仪研究合金的微观组织、导热率与热膨胀系数。结果表明：选择合理的优化工艺参数, W-Ni-Cu(SLM)成形致密度最高达到94.5%; 微观组织为难熔相W发生了桥接与团聚, 基体相CuNi呈网络状包裹于W相周围; 测试试样所加载热流平行于烧结成形方向时, 导热系数与热膨胀系数分别是120.314 0 W/(m·K)及7.16×10-6/K, 加载热流方向垂直于烧结成形方向时, 导热系数与热膨胀系数分别是99.257 2 W/(m·K)及7.02×10-6/K。不同方向成形测试件导热系数和热膨胀系数的差异是由难熔相W在CuNi相中的分布以及孔隙数量决定的。采用选区激光熔化成形技术可以成形性能较好的W-Ni-Cu合金。

To investigate the process and thermal physical performance of W-Ni-Cu manufactured using the Selective Laser Melting (SLM) technique, an experiment of four variables was conducted to study the influence of laser power, scanning speed, length of the scanning line, and overlap rate on the density. Scanning electron microscopy as well as a thermal analyzer, differential scanning calorimeter, and thermal-mechanical analyzer were used to study the microstructure, thermal conductivity, and thermal expansion. The results show that the density of W-Ni-Cu reaches 94.5% with the optimized process. The microstructure is a type of bridging connection, and agglomeration occurs between the W phases and CuNi phase that wraps around the W phase like a network. When the measuring direction is parallel to the processing direction, the thermal conductivity and thermal expansion coefficients are 120.314 0 W/m·K and 7.16×10-6/K, respectively. When the measuring direction is perpendicular to the processing direction, the thermal conductivity and thermal expansion coefficients are 99.257 2 W/m·K and 7.02×10-6/K, respectively. Test pieces form in different directions with different thermal conductivity and thermal expansion coefficients because of the distribution of W in CuNi and the existence of pores. The study shows that the W-Ni-Cu alloy parts exhibiting better performance can be manufactured directly using SLM.