Effect of hot isostatic pressing on nanoparticles reinforced AlSi10Mg produced by selective laser melting

Abstract

Additive manufacturing (AM) technologies are being rapidly adopted for producing high-performance components in industry, and selective laser melting (SLM) is the predominant AM process for producing metal alloy parts. To improve the mechanical properties of additively manufactured metallic materials, various approaches have been proposed in literature. Among them, adding nano reinforcement and applying hot isostatic pressing (HIP) are regarded as two effective methods. This research investigates the combined effect of the two methods on the microstructure and mechanical properties of SLM produced AlSi10Mg. The results show that both nano reinforcement and HIP have significant effect in enhancing the microstructure and the resulted tensile properties. Under the as-built condition, 3% of nano TiC particles in weight leads to significantly refined grain size and dendrite arm spacing. The yield strength increases by 39.8% under the as-built condition as compared to the unreinforced sample. However, the addition of nanoparticles decreases the flowability of powder and increases the porosity of solidified material, which in turn causes a significant reduction in material ductility. Further, HIP is found to be able to reduce internal defects effectively. Nanoparticles are effective in preventing the microstructure from coarsening during the HIP. As a result, HIP processed nano TiC particles reinforced AlSi10Mg have homogenized defect-free microstructure and significantly enhanced tensile properties, without an obvious sacrifice of material ductility. Compared to unreinforced materials, the increases of yield strength and ultimate tensile strength are 14.9% and 33.9%, respectively. The elongation at fracture reaches 11%.