A comprehensive model to quantify the effects of additional nano-particles on the printability in laser powder bed fusion of aluminum alloy and composite

Abstract

At present, it is recognized that nanoparticles can improve the printability of many metals in fusion additive manufacturing, obtain finer microstructures and higher mechanical properties. However, it is unclear how nanoparticles affect the printing process and the extent of the effect. Numerical simulation can realize such a quantitative study. Here, we developed a method to quantify the effects of nano-particles on the printability in laser powder bed fusion with multiple physics simulation model, with the consideration of surface tension, Marangoni effect, phase transition and recoil force via volume of fluid method. The influence of nanoparticles as well as thermal properties on the molten pool morphology, temperature distribution and cooling rate were studied. The results showed that TiB2/AlSi10Mg possessed higher cooling rate and larger melt pool depth, which is consistent with single track experimental result. The G-R solidification map indicated that for the specific points in the mush zone, percentages of them in equiaxed, mixed and columnar region for TiB2/ AlSi10Mg are 14.29%, 76.19% and 9.52%, respectively, revealing that TiB2 can lead to the transition from the columnar region to the equiaxed one, which was also confirmed by the experimental EBSD map. The study on thermophysical properties indicated that thermal conductivity had the largest influence on the characteristic of molten pool, which can be used as a strategy to optimize the quality in practical application. By introducing the printability factor F, we determined that the printability of AlSi10Mg and different particles decorated AlSi10Mg is in the following order: TiB2/AlSi10Mg > TiC/AlSi10Mg > SiC/AlSi10Mg > AlSi10Mg. This work provides a theoretical framework to predict the printability and efficiently screen for promising metal materials with good printability.