采用扫描透射电镜(STEM)和动态机械分析仪(DMA)研究了FeCrMoCu合金(Cu添加量为1.0%和2.0%,质量分数)在不同冷速条件下Cu的析出行为及其对阻尼性能和力学性能的影响。结果表明：1.0Cu合金中Cu主要以过饱和的形式固溶在基体,当冷速较慢(炉冷)时会析出少量的富Cu相,该相尺寸较小(<5 nm),Cu含量较低(3.7%);Cu增加到2.0%后,随着冷速的下降(从水冷到空冷,最后到炉冷),合金中先析出数量较少、尺寸较小的富Cu相,随后析出数量较多、尺寸稍大的球状第二相(10~15 nm),最后析出相粗化成圆棒状(100~400 nm)但数量显著减少,后2种析出相的Cu含量明显增加(30%~40%)。含Cu第二相的析出,明显增加合金平均内应力,使合金的阻尼性能显著下降,因此有第二相析出的2.0Cu合金阻尼性能明显低于1.0Cu合金。与此同时,合金的强度随着富Cu相的析出而明显提高,其中尺寸较小的富Cu相析出强化效果较好,且对塑韧性的影响相对较小。含1.0%Cu的FeCrMoCu合金可以同时获得较好的阻尼性能和力学性能。

Fe-Cr based damping alloys have high mechanical properties and good corrosion resistance, which have been applied to reduce vibration and noise. Their high damping behavior is primarily attributed to the stress-induced irreversible movement of 90° magnetic domain walls. Most researches mainly focused on the damping behavior of these alloys. However, little attention has been paid to the mechanical properties, which are the important consideration for engineering applications. Recently, a FeCrMo damping alloy with Cu addition was found to possess higher damping capacity and higher mechanical properties. In this work, scanning transmission electron microscopy (STEM) and dynamic mechanical analyzer (DMA) were used to investigate the Cu precipitation and its influences on damping capacity and mechanical properties of FeCrMoCu alloy (1.0% and 2.0% Cu addition, mass fraction) with dif ferent cooling rates. The results show that the Cu element in 1.0Cu alloy is fully dissolved in the matrix. When the cooling rate is slow (furnace cooling), there will precipitate a small amount of second phases, which are small in size (<5 nm) and contain relatively few Cu atoms (3.7%). As for 2.0Cu alloy, with decreasing cooling rate (from water cooling to air cooling, and to furnace cooling) there will firstly precipitate a small amount of second phase with small size (<5 nm); subsequently, the particles grow into a spherical shape (10~15 nm) and their number increases; at last, the particles transform into round bar with coarse size of 100~400 nm and the precipitate number decreases obviously. The Cu content of the latter two precipitates increased obviously (about 30%~40%). These precipitates will significantly increase the average internal stress of the experimental FeCrMoCu alloy, which will obviously decrease the damping capacity. Therefore, the damping capacity of 2.0Cu alloy is much lower than that of 1.0Cu alloy. Meanwhile, the precipitate will obviously improve the strength. Compared with coarsen Cu-riched phase, the finer second phase has better hardening effect and its influence on ductility and toughness is relatively small. The FeCrMoCu alloy with addition of 1.0% Cu can obtain better damping capacity and mechanical properties at the same time.