2021 Volume 68 Issue 8 Pages 311-316
Binder jetting (BJT) holds enormous promise as an additive manufacturing technique due to its high throughput and low-cost equipment. The ability to fabricate geometrically complex parts from aluminum alloy via BJT would have a significant impact on the development of high-performance machine components and heat-dissipation devices. However, processing printed objects by sintering of aluminum alloy is difficult due to the surface oxide layer that covers the powder particles, which prevents the final parts from reaching a sufficiently high density. In order to investigate the sintering mechanism for controlling the quality of sintered parts, we directly observed the sintering behavior of pure Al and Al-10%Si-0.4%Mg (mass%) alloy using an in situ scanning electron microscopy system equipped with a heating stage. It is found that the surface roughness of the powder particles is reduced above their melting or solidus temperature. Subsequently, the liquid ruptures the oxide layer and forms necks between the particles.
