Effect of silver addition in copper-silver alloys fabricated by laser powder bed fusion in situ alloying

Abstract

In this study copper-silver (CuAg) structures with varying Ag content were fabricated by in situ alloying and Laser Powder Bed Fusion (L-PBF) Additive Manufacturing (AM). Powder morphology, distribution and elemental analysis were conducted using Scanning Electron Microscopy (SEM) and dynamic imaging for CuAg10, CuAg20 and CuAg30 atomised powder. The resultant pore defect morphology and distribution for each as built and annealed CuAg alloy structure was investigated and reported using X-ray Computed Tomography (XCT) and 3D visualisation. The atomic crystal structure for each as built and annealed CuAg alloy is reported through X-Ray Diffraction (XRD) analysis. Yield strength, Young’s Modulus, failure strain and Ultimate Tensile Strength (UTS) of as built and annealed AM CuAg structures are reported and sample fracture surfaces were analysed using SEM and Energy Dispersive X-Ray (EDX) techniques. Increased Ag content from CuAg10% to CuAg30% is shown to decrease the number of pore defects by 87% and 83% for as built and annealed samples with average pore size decreasing by 40% and 9.5%. However, the annealing process was found to increase the porosity by up to 164%. Furthermore, the annealing process resulted in atomic lattice contractions resulting in increased yield strength, Youngs Modulus and Ultimate Tensile Strength (UTS) for CuAg30%.