Gas atomization of AA2017 aluminum alloy: Effect of process parameters in the physical properties of powders for additive manufacturing

Close-coupled gas atomization (CCGA) uses pressurized gas jets to atomize molten metals, producing powders suitable for additive manufacturing (AM). Optimization of processing parameters is crucial to achieve powders with good fluidity and high apparent density for laser powder bed fusion (L-PBF) and increase production yield. This study evaluated the influence of melt feed nozzle diameter, superheating temperature, and atomization pressure on AA2017 aluminum alloy powders' physical properties. Parameters variation poorly affected the median particle diameter (d50), while significantly altering the particle size distribution curves width (IDR = d90-d10). Suitable powders for AM/L-PBF were produced using a specific set of parameters (d0= 1.5 mm; ΔT= 150 °C; PG= 20 Bar), presenting appropriate fluidity and apparent density due to an optimal granulometric distribution and morphological characteristics. Mathematical analysis showed a good correlation between experimental and calculated mean particle size, suggesting an equation to predict percentile d90 based on previous correlations

Processing, as-cast microstructure and wear characteristics of a monotectic Al-Bi-Cu Alloy

Ternary Al-based monotectic alloys have a good combination of wear resistance and mechanical strength. While self-lubricating soft elements guarantee an adequate wear resistance, the modification with third elements can increase the ability to support load. In the present investigation, a collection of microstructures is generated through transient directional solidification of the Al-3.2wt.%Bi-3.0wt.%Cu alloy. Samples with different Bi spacing have been subjected to micro-adhesive wear ball tests. A relationship linking the wear volume, V, the microstructural spacing and the test time is proposed for Bi spacing higher than 16m, according to which V decreases with the decrease in Bi spacing. It is observed that wider and deeper grooves emerged on the surface of the samples related to more refined Bi and Al2Cu phases, that is, associated with Bi spacing and Bi diameter lower than 16 and 2.4m, respectively. A reverse trend is noted for these finer microstructures, for which V increases with further decrease in Bi spacing. This can be caused by the detachment of the very fine and less cohesive Al2Cu lamellas as the Al2O3 oxide breaks up forming debris, with the presence of these lamellas as loose debris at the interface acting as third-body abrasives28212011212CNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulosem informação2017/12741-6The authors are grateful to FAPESP (São Paulo Research Foundation, Brazil: Grant 2017/12741-6) and CNPq- National Council for Scientific and Technological Development, for their financial suppor