Damping Properties of Selective Laser-Melted Medium Manganese Mn-xCu Alloy

In this work, selective laser melting (SLM) technology was applied to directly realize the in situ synthesis of medium manganese Mn-xCu (x = 30-40 wt.%) alloys based on the blended elemental powders. The effects of heat treatment on the microstructural evolution and damping properties of the SLMed Mn-xCu alloys were investigated. The metastable miscibility gap was studied by thermodynamic modeling and microhardness measurement. The results showed that gamma-(Mn, Cu) phase with dendritic arm spacing (DAS) of 0.9-1.2 mu m was the main constituent phase in the as-SLMed alloys, which was one to two orders of magnitude finer than those of the as-cast samples. Aging at 400-480 degrees C for the Mn-30%Cu or 430 degrees C for Mn-40%Cu alloys can induce spinodal decomposition, martensitic transformation, and alpha-phase precipitation, whose direct evidence was provided for the first time by transmission electron microscopy and 3D atom probe tomography in the work. The miscibility gap obtained from thermodynamics calculation was basically consistent with the microhardness results for the SLMed Mn-xCu alloys. Solution and aging (SA) treatment can improve the microstructure, tensile and damping properties of the SLMed Mn-xCu alloys more obviously than aging treatment. A 2.3-2.8 and 4.3-4.5 times increase was produced in damping capacity in the aged SLMed and SLMed+SAed Mn-xCu samples, respectively.

Automated summary

In this study, the selective laser melting technology was used to synthesize medium manganese Mn-xCu alloys directly from blended elemental powders. The effects of heat treatment on the microstructure and damping properties of the alloys were investigated. The results showed that solution and aging treatment significantly improved the damping capacity of the alloys.