A Review of the Physical Metallurgy and Damping Characteristics of High Damping Cu-Mn Alloys

Abstract

This paper reviews the physical metallurgy and damping characteristics of copper-manganese (Cu-Mn) alloys. Many of the examples given in this paper are based upon the authors' experimental investigations of an alloy with nominal composition (composition in weight percent) of 48Cu-48Mn-1.5Al-0.27 Si-0.072Sn-0.028C-0.05Er. The results for this material were obtained in a bending mode, and the reported strain amplitudes represent the maximum surface strain imposed. Damping in these materials is very sensitive to heat treatment and carbon content. Recent work has shown that carbon in solid solution is detrimental to the damping capacity and results in a strain aging behavior and subsequent loss of damping capacity when stored at room temperature. Copper-manganese alloys can lose more than 50% of their damping capacity during room temperature storage. The role of erbium in the stabilization of the damping capacity is explained in the context of the physical metallurgy of the Cu-Mn system.

Special Features of Formation of the High Damping State in Bimetallic Structural Materials Obtained by Explosion Welding

“…This factor is very important for layered composite materials due to valuable difference between coefficients of thermal expansion of components of the bimetal. The most probably small influence of external static stresses on damping characteristics of the 60%Mn-40%Cu alloy can be observed because this alloy can be characterized by specific structure formed during thermoelastic martensitic transformation [3,4]. Material structure formed during the thermoelastic FCC-FCT (face-centered cubic -facecentered tetragonal) martensitic transformation in Mn-Cu alloys can be characterized by high tetragonal distortions at the room temperature and by high level of internal stresses on the boundaries of tetragonal domains [3,4], providing a good basis for realization of weak dependence of material properties on static stresses applied in the elastic region.…”

High-Damping State in Structural Bimetals Obtained by Explosion Welding

“…Незначительное влияние внешних статических напряжений на демпфирующие характеристики сплава 60Mn-40Cu связано со специфическим характером структуры, образующейся при термоупругом мартенситном превращении [3,4]. В сплавах Mn-Cu в процессе ГЦК-ГЦТ превращения формируется структура, характеризующаяся высоким уровнем внутренних напряжений, возникающих на границах тетрагональных доменов [3,4], что и обуславливает слабую зависимость свойств материала от внешних статических напряжений, приложенных в упругой области.…”