The Study On High Damping Mn-Cu-Ni-Fe Alloy

In order to improve the damping capacity of Mn-Cu alloys, we designed and chosen Mn77 6Cu19 9Ni6 0Fe2 4(at.%), Mn798Cu193Ni47Fe22(at.%) and Jncramute alloy (Cu-45Mn-2A1 wt.%). In this paper, the changing roles of internal friction, modulus, hardness, intensity of the three alloys in different treatment conditions are studied What this paper studies includes: 1) The influence of cooling rates on the damping behavior of Mn-Cu-Ni-Fe alloy. 2) The effect of the aging temperature on damping capacity of alloys. 3) The change of internal friction during the aging treatment. 4) The influence of heat treatments on mechanical properties of alloys. The results show that: 1) The internal friction of slowly cooled alloys is higher than water quenched alloys. There are no phase transformation in the water quenched materials, which induced the low internal friction; According to the decomposition of Y ~ phase during continuous cooling, large amounts of Mn-riched regions can be formed. The chemical inhomogeneity in alloys induces to the martensite transformation and twin plates are formed, Under the influence of stress, the movement of phase boundaries and twin interfaces causes to a high internal friction. 2) It is out of spinodal curve that aging at 3000C, phase transformation cannot occurs at this temperature, so high damping capacity cannot be reached. 3) Aging at 400æ“Ÿ, large amounts of Mn-riched regions and Cu-riched regions can be formed during the spinodal decomposition. The formation of large Mn-riched regions in alloy is the source of high internal friction; and with the increasing of aging time, the Mn-riched regions become larger, which induce to the improvement of internal friction and transformation temperature. 4) The influence of heat treatment on mechanical properties of alloys is same as II the effect on internal friction. It shows that the mechanisms of them are also same. They are both caused by the martensite transformation and the degree of it. 5) The Mn79 8Cu193Ni4 7Fe22(at.%) alloy that the author designed shows a ideal and a higher damping capacity then Incramute alloy.