MoNbTiV high-entropy alloy was in situ alloyed with laser power-blown directed energy deposition additive manufacturing from a mixture of four elemental powders of Mo, Nb, Ti, and V. This study provides a fundamental understanding of the alloying process through in situ high-speed synchrotron X-ray imaging and infrared imaging. High-speed X-ray imaging was used to investigate the in situ alloying process through direct observation. The particle delivery velocities of four different elemental powders under the same processing conditions were studied to reveal the performance of the powders during the in situ alloying process. We found that the Ti and Nb powders showed the greatest and smallest averaged particle-delivery velocities among these four powders, respectively, and the particle delivery velocity would be affected by the particle characteristics, particle size, and density of powders. The velocities of the resulting melt pool flow were measured to show the melt flow dynamics in such a process. The residence time of each elemental powder was also obtained, and Mo powders showed the largest residence time followed by Nb, V, and Ti powders. The porosity induced by unmelted particles and entrapped gas occurred in the alloying process. The Mo powders resulted in the most unmelted particles, and the entrapped gas porosity was mainly induced by the keyhole fluctuation. With the assistance of an infrared camera, we reported the emissivity of the melt pool, the change of thermal properties, and melt pool morphology during alloying.

MoNbTiV 高熵合金采用激光功率吹制定向能量沉积增材制造，由 Mo、Nb、Ti 和 V 四种元素粉末的混合物原位合金化。本研究通过原位高温对合金化过程提供了基本的了解。 -高速同步加速器X射线成像和红外成像。高速 X 射线成像用于通过直接观察研究原位合金化过程。研究了在相同加工条件下四种不同元素粉末的粒子传输速度，以揭示粉末在原位合金化过程中的性能。我们发现 Ti 和 Nb 粉末在这四种粉末中分别表现出最大和最小的平均粒子传输速度，并且颗粒输送速度会受到颗粒特性、颗粒尺寸和粉末密度的影响。测量所得熔池流动的速度以显示这种过程中的熔体流动动力学。还获得了每种元素粉末的停留时间，Mo 粉末的停留时间最长，其次是 Nb、V 和 Ti 粉末。在合金化过程中出现了由未熔化的颗粒和夹带的气体引起的气孔。钼粉产生的未熔化颗粒最多，夹带气孔主要是由小孔波动引起的。在红外相机的帮助下，我们报告了熔池的发射率、热性能的变化以及合金化过程中的熔池形态。测量所得熔池流动的速度以显示这种过程中的熔体流动动力学。还获得了每种元素粉末的停留时间，Mo 粉末的停留时间最长，其次是 Nb、V 和 Ti 粉末。在合金化过程中出现了由未熔化的颗粒和夹带的气体引起的气孔。钼粉产生的未熔化颗粒最多，夹带气孔主要是由小孔波动引起的。在红外相机的帮助下，我们报告了熔池的发射率、热性能的变化以及合金化过程中的熔池形态。测量所得熔池流动的速度以显示这种过程中的熔体流动动力学。还获得了每种元素粉末的停留时间，Mo 粉末的停留时间最长，其次是 Nb、V 和 Ti 粉末。在合金化过程中出现了由未熔化的颗粒和夹带的气体引起的气孔。钼粉产生的未熔化颗粒最多，夹带气孔主要是由小孔波动引起的。在红外相机的帮助下，我们报告了熔池的发射率、热性能的变化以及合金化过程中的熔池形态。和钛粉。在合金化过程中出现了由未熔化的颗粒和夹带的气体引起的气孔。钼粉产生的未熔化颗粒最多，夹带气孔主要是由小孔波动引起的。在红外相机的帮助下，我们报告了熔池的发射率、热性能的变化以及合金化过程中的熔池形态。和钛粉。在合金化过程中出现了由未熔化的颗粒和夹带的气体引起的气孔。钼粉产生的未熔化颗粒最多，夹带气孔主要是由小孔波动引起的。在红外相机的帮助下，我们报告了熔池的发射率、热性能的变化以及合金化过程中的熔池形态。