Synergistic strengthening mechanism of cryogenic treatment for mechanical properties and damping characteristics of Mn–Cu alloy

Abstract

Mn–Cu alloys are widely used as shock absorption and noise reduction materials in engineering fields. However, the strengthening of their mechanical properties often leads to a decrease in damping performance, which limits the further application of these alloys. To overcome this limitation, this paper systematically investigated the effects of different cryogenic treatment times (−196 °C) (0 h, 12 h, 24 h, 36 h) on the microstructure, mechanical properties and damping behavior of the Mn–Cu alloy. The results show that cryogenic treatment can effectively increase the internal dislocation density of the alloy, promote the refinement of the α -Mn phase, increase the proportion of the Mn-rich region, and induce the FCC→FCT martensitic phase transformation to improve the formation of twinning. As the cryogenic time increases, the tensile strength and hardness of the alloy increases, but the elongation decreases slightly. Cryogenic treatment introduces a large number of dislocations in the alloy, which makes the damping performance of the alloy exhibit a synergistic strengthening effect of twinning damping and dislocation damping mechanisms at different temperatures, providing a new method for the development of high-performance of Mn–Cu alloys.