Qualification of a Ni–Cu Alloy for the Laser Powder Bed Fusion Process (LPBF): Its Microstructure and Mechanical Properties

Abstract

As researchers continue to seek the expansion of the material base for additive manufacturing, there is a need to focus attention on the Ni–Cu group of alloys which conventionally has wide industrial applications. In this work, the G-NiCu30Nb casting alloy, a variant of the Monel family of alloys with Nb and high Si content is, for the first time, processed via the laser powder bed fusion process (LPBF). Being novel to the LPBF processes, optimum LPBF parameters were determined, and hardness and tensile tests were performed in as-built conditions and after heat treatment at 1000 °C. Microstructures of the as-cast and the as-built condition were compared. Highly dense samples (99.8% density) were achieved after varying hatch distance (80 µm and 140 µm) with scanning speed (550 mm/s–1500 mm/s). There was no significant difference in microhardness between varied hatch distance print sets. Microhardness of the as-built condition (247 HV0.2) exceeded the as-cast microhardness (179 HV0.2.). Tensile specimens built in vertical (V) and horizontal (H) orientations revealed degrees of anisotropy and were superior to conventionally reported figures. Post heat treatment increased ductility from 20% to 31% (V), as well as from 16% to 25% (H), while ultimate tensile strength (UTS) and yield strength (YS) were considerably reduced.

Analysis of processing efficiency, surface, and bulk chemistry, and nanomechanical properties of the Monel® alloy 400 after ultrashort pulsed laser ablation

“…Monel ® alloy 400, an alloy of Ni-Cu, is a widely researched material because of its numerous and diverse applications in industries such as aerospace, high steam generators, nuclear, chemical, gas and oil, and food processing [1]. Additionally, due to its unique properties of excellent corrosion resistance to a wide range of corrosive environments and its resistance to a ductile-to-brittle phase transition even at below-zero temperatures, Monel ® alloy 400 is used in marine industries [2].…”

Special Issue on Materials Development by Additive Manufacturing Techniques

“…Recently other alloys belonging to the Ni family have been successfully processed by AM. As an example, in this special issue, results about the Monel Ni-Cu alloy are reported [14]. This alloy, which has been recently processed by LPBF, showed good processability within specific parameters.…”

“…This alloy, which has been recently processed by LPBF, showed good processability within specific parameters. High-mechanical properties were measured thanks to fine microstructure and high residual stresses [14].…”

Influence of heat treatment on microstructure, mechanical and corrosion behavior of WE43 alloy fabricated by laser-beam powder bed fusion

“…As a comparison, fine and uniform equiaxed grains were observed within the molten pool. This characteristic could be partially explained by the nature of localized heating during PBF-LB [35]. Upon melting, the solidification process occurred directionally from the molten pool boundary due to a high ratio of thermal gradients (G) and low growth rate (R) [36,37].…”