Numerical and experimental study of RHEAs surface morphology and defect in selective laser melting

Abstract

Refractory high-entropy alloys (RHEAs) are a new category of high-temperature materials that are high-entropy alloys with refractory metal elements as the major components. SLM technique provides distinct benefits in preparing refractory metals with high melting points. The effects of laser power and scanning speed on the surface morphology and internal defects of VNbMoTaW RHEAs samples were examined using numerical and experimental methods. A DEM-CFD model was created to simulate the process of SLM producing a single-layer, single-track model. The simulation findings show that the melt pool's channel width is 62.31 μm at a scanning speed of 300 mm/s and a laser power of 150 W. The channel width grows to 96.92 μm when the laser power rises to 450 W. When the laser power is increased, the channel becomes flatter. To prepare the VNbMoTaW samples, the process parameters with the highest quality in the numerical simulation were chosen. At a scanning speed of 300 mm/s and a laser power of 450 W, the measured channel width of the high-entropy alloy samples is approximately 104.13 m. Similarly to the numerical simulation results, the channel width of the models generated at the same scanning speed increases as the laser power increases. At low laser power, it was discovered that many unmelted powder particles were dispersed on the surface of the samples. The primary defects found in the samples were pores and fractures. The interlayer non-melting cracks on the sample cross-section vanish at elevated laser power. Whereas the quality of samples created at low scanning speeds is higher at the same laser power, the quality of samples declines as the scanning speed of the laser increases.