Cu的析出及其對FeCrMoCu合金阻尼性能和力學性能的影響

Cu的析出及其對FeCrMoCu合金阻尼性能和力學性能的影響CU PRECIPITATION AND ITS EFFECT ON DAMPING CAPACITY AND MECHANICAL PROPERTIES OF FECRMOCU ALLOY

采用掃描透射電鏡（STEM）和動態(tài)機械分析儀（DMA）研究了FeCrMoCu合金（Cu添加量為1.0%和2.0%）在不同冷速條件下Cu的析出行為及其對阻尼性能和力學性能的影響。結果表明：在1.0Cu合金中Cu主要以過飽和的形式固溶在基體，當冷速較慢時會析出少量的富銅bcc-Cu相，該相尺寸較小（< 5 nm），與基體共格；Cu增加到2.0%后，隨著冷速的降低，先析出數量較少、尺寸較小的富銅bcc-Cu相，隨后析出相長大呈球狀（10~15 nm）且數量增多，最后粗化成圓棒狀（100~400 nm）但數量顯著減少，后兩種析出相均為非共格的ε-Cu相。含Cu第二相的析出，明顯增加合金平均內應力，使合金的阻尼性能顯著下降，因此有第二相析出的2.0Cu合金的阻尼性能明顯低于1.0Cu合金。與此同時，合金的強度隨著Cu相的析出而明顯提高，其中富銅bcc-Cu相的析出強化效果較好，且對塑韌性的影響相對較小。含1.0%Cu的FeCrMoCu合金可以同時獲得較好的阻尼性能和力學性能。

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. Recently, a FeCrMo damping alloy with addition of Cu was found to possess higher damping and high mechanical properties. In the present paper, 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) with different cooling rates. The results show that the Cu element in 1.0Cu alloy is fully solid solution in the matrix. When the cooling rate is slow, there will precipitate a small amount of second phases, which are Cu-riched, small in size of < 5 nm and coherent with the matrix. As for 2.0Cu alloy, with decreasing cooling rate there will firstly precipitate a small amount of bcc-Cu with small size. 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 latter two kinds of particles are non-coherent ε-Cu phases. 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 significantly lower than 1.0Cu alloy. Meanwhile, the precipitate will obviously improve strength. Compared with ε-Cu phase, the bcc-Cu 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.

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