Effect of heat treatment on microstructure and damping properties of MnCu-based damping alloy prepared by laser powder-bed-fusion (LPBF)

Abstract

MnCu alloys are widely recognized for their high damping performance and strength, making them ideal for aerospace and marine applications. This study aims to explore the effects of solution aging on the microstructure, phase transformation, mechanical properties, and damping characteristics of MnCuNiFe alloys fabricated via Laser Powder Bed Fusion (LPBF). A series of advanced characterization techniques, including EDS, high-resolution imaging, and XRD, were employed to analyze microstructural evolution and its impact on performance. The results reveal that increasing solution temperatures generally enhances the strength and ductility of the alloy compared to conventionally cast alloys, while "strip-like" Fe enrichment becomes more prominent near phase boundaries. Heat treatment enhances damping capacity threefold compared to as-deposited samples, primarily due to spinodal decomposition, which promotes the formation of tweed-like microstructures, nano-twin layers, and fct ordered structures. Additionally, the development of Cu-rich nanodomains (50–85 nm thick), spherical Al oxides, and strip-like Mn oxides surrounding α-Mn precipitates contributes to improved energy dissipation. These microstructural changes, confirmed by EDS and high-resolution imaging, facilitate internal friction mechanisms that enhance damping performance. The study showcases LPBF as a promising method to fabricate high-performance damping MnCu alloys, providing insights into microstructural design and optimization through heat treatment.