Preparation of phosphor bronze powders by arc erosion of wires: Microstructure and mechanical properties

Abstract

The rapid development of the new-energy industry has placed increasing demands on connectors. Additive manufacturing provides an effective strategy for fabricating complex connector contact components, for which phosphor bronze powder is a promising feedstock owing to its excellent mechanical strength and electrical conductivity. To meet these requirements, high-quality phosphor bronze powders were prepared in this study using the arc erosion of wires (AEW) method. Spherical QSn6–0.1, QSn7–0.2, and QSn8–0.3 powders with smooth surface and low satellite content were successfully produced. Their solidification structure and mechanical properties were systematically examined using X-ray diffraction, scanning electron microscopy, and single-powder compression testing. All powders consist primarily of α-Cu and δ-Cu₄₁Sn₁₁ phases despite the difference in composition. The ultrahigh cooling rate during AEW promotes uniform solidification structure without apparent defects and effectively suppresses Sn inverse segregation. Powder diameter, rather than composition, dominates the solidification behavior: smaller powders experience faster cooling, resulting in finer solidification structures and smaller secondary dendrite arm spacing. Single-powder compression tests reveal that powder hardness increases with decreasing diameter. Analysis of the strain-hardening rate indicates a size-dependent deformation mechanism: larger powders exhibit a pronounced hardening peak associated with the formation of stacking faults due to the alloy's low stacking-fault energy, whereas this effect is suppressed in smaller powders. This study presents a novel method for producing phosphor bronze powders, and the findings offer valuable insights into tailoring their solidification and mechanical behavior for additive manufacturing applications.