Characterization of Copper-Nickel Alloys Fabricated using Laser Metal Deposition and Blended Powder Feedstocks

In the current study, the feasibility of fabricating copper—nickel alloys by using laser metal deposition and blended powder feedstocks was investigated through material characterization. Material fabricated from the blended powder mixtures containing elemental nickel was seen to possess large amounts of gas and shrinkage porosity. Due to this porosity, elemental nickel powder was deemed to be an unviable modular feedstock. Instead, Delero-22, a high nickel content alloy, was identified as a viable substitute for elemental nickel. The silicon and boron alloy additions in Delero-22 alloy were identified to be crucial in overcoming the porosity prevalent when using elemental nickel. Counterparts to commercially available copper—nickel alloys were then fabricated using blended elemental copper and Delero-22 alloy powders. Thus, fabricated alloys were characterized using X-ray diffraction, scanning electron microscopy, Vickers hardness testing, energy-dispersive X-ray spectroscopy, and mini-tensile testing. Analyses revealed that the deposited material was formed with homogenous microstructure and the resultant compositions were close to as-blended feedstocks. The results from tensile testing showed an increase in strength caused by solid solution strengthening upon addition of copper to nickel. The addition of copper also increased the ductility of the material. Analysis of the fracture surface revealed changes in the fracture mechanism from transgranular to ductile with an increase in copper content. Variation in scan speed during laser metal deposition resulted in a change in average secondary dendrite arm spacing and variability in tensile performance.