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Mn-Cu系阻尼合金兼有较高的阻尼特性和良好的力学性质,因而具有较大的实用前景。这类合金通常经过铸造,塑性加工和热处理来获得要求的性能和组织。加工后的Mn-Cu合金存在一个特定温度,在此温度以上合金的阻尼性能将会消失,因而影响了合金的在较高温度下的使用。该温度和合金的Mn含量有关,然而提高合金的Mn含量有会降低合金的加工性及力学性能。一般Mn-Cu合金的热处理都是利用400℃附近的时效来获得相分解后的局部高Mn组织。但是目前的时效处理后的Mn-Cu阻尼合金的最高使用温度只在80℃以下。为解决Mn-Cu阻尼合金使用温度的局限性,本研究选用凝固过程控制的方法在铸造组织中来获得较大幅度的Mn含量分布,从而在Mn-Cu合金得到较高的高阻尼特性温度。本工作利用铸型温度控制的方法,将M2052(Mn-20Cu-5Ni-2Fe)合金在250~0.1 K/s冷却速度范围内控制凝固。随凝固冷却速度的降低在合金的铸态组织中观察到二次枝晶间距和晶粒尺寸的明显增大。同时还发现缓冷凝固的合金的成分比快冷凝固有较大的分布幅度。铸态下的合金阻尼性能评价也证实了凝固冷却速度对合金的凝固组织有很大的影响。尽管铸态组织的合金的高温阻尼性能并没有很大的改善,然而通过对铸态组织实施时效处理后发现缓冷凝固合金的高温阻尼性能有很大的改善。凝固冷却速度对时效处理后合金的阻尼性能有明显的影响。实验结果表明0.1 K/s的冷却速度下缓慢凝固的合金在时效处理后高阻尼特性可持续高达120℃。
Mn-Cu damping alloy both high damping properties and good mechanical properties, which has a larger practical perspective. These alloys are usually cast, plastically worked and heat treated to achieve the desired properties and texture. The processed Mn-Cu alloy has a specific temperature at which the damping properties of the alloy will disappear, thus affecting the alloy's use at higher temperatures. The temperature and the Mn content of the alloy, however, to improve the alloy Mn content will reduce the alloy's workability and mechanical properties. The general Mn-Cu alloy is the heat treatment is the use of aging near 400 ℃ to obtain phase decomposition of local high Mn organization. However, the current aging treatment of Mn-Cu damping alloy maximum temperature only 80 ℃ below. In order to solve the limitation of the service temperature of Mn-Cu damping alloy, the control method of solidification process is adopted to obtain a large distribution of Mn content in the cast structure, so as to obtain higher high damping characteristic temperature in Mn-Cu alloy. In this work, the M2052 (Mn-20Cu-5Ni-2Fe) alloy was controlled to be solidified at the cooling rate of 250 ~ 0.1 K / s by the method of mold temperature control. As the solidification cooling rate decreases, a significant increase in secondary dendrite spacing and grain size is observed in the as-cast microstructure of the alloy. At the same time, it was also found that the composition of slow-freezing solidified alloy has a larger distribution range than that of rapid solidification. The evaluation of the damping performance of the as-cast alloy also confirms that the solidification cooling rate has a great influence on the solidified structure of the alloy. Although the high-temperature damping properties of the as-cast alloy are not greatly improved, the high-temperature damping properties of the annealed solidified alloy have been found to be greatly improved by the aging treatment of the as-cast structure. The solidification cooling rate has a significant effect on the damping properties of the alloy after aging treatment. The experimental results show that the alloy with slow solidification at a cooling rate of 0.1 K / s has a high damping property up to 120 ℃ after aging treatment.