| The purpose of this research is to develop a high-damping,high service temperature Mn-Cu damping alloy,and a Mn-19Cu-5Ni-2Fe alloy rod with a diameter of 80 mm was prepared byvacuum induction melting technology.By means of optical microscope,scanning electronmicroscope,transmission electron microscope,X-ray diffractometer,dynamic mechanics analyzer,universal material testing machine,hardness tester and other testing instruments,the effects of solid solution and aging process on the microstructure,martensitic transformation,precipitated phase,mechanical and damping capacity of the alloy were studied systematically,and the relationship between microstructure and properties was established.The main results are as follows:?1?the solution temperature has a significant effect on the properties of Mn-19Cu-5Ni-2Fe alloy,which can reduce the resistance of amplitude modulation decomposition and promote the formation of thermoelastic martensite.High solution temperature can easily lead to the formation of?-Mn after aging,and a small amount of?-Mn can reduce the mechanical and damping properties.Based on the change of Q-1 with solution temperature,the optimum solution temperature is determined as 900?.?2?the alloy was aged at different temperature?385535??and different time?124 h?after solid solution treatment at 900?×1 h.It was found that with the increase of aging temperature or aging time,the internal friction,strength and hardness increased first and then decreased.The main reason is that aging treatment promotes spinodal decomposition,which makes the alloy obtain a large number of martensite and martensite twin interface.And during the over aging period,?-Mn was easy to precipitate and grow,leading to the deterioration of damping and mechanical properties.?3?the alloy was cooled in different ways?air cooling,furnace cooling and step-cooling?after aging.It is found that the step-cooling sample has the best damping capacity,the Q-1 can reach 0.130 and the MS can reach 76.4?.Step-cooling significantly improves the damping capacity,which is attributed to the further increased Mn content in the Mn-rich zones due to the aging at the low temperature side,and the smaller cooling rate inhibits the nucleation and growth of?-Mn. |
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