Mn-Fe基合金的反铁磁与高阻尼

On the antiferromagnetism and high damping capacity of Mn-Fe alloys

采用动力学分析 (DMA)和透射电子显微分析 (TEM )等实验方法 ,研究了含锰 45 .9%～ 86 .4% (原子分数 )范围Mn Fe (Cu)合金的反铁磁转变、马氏体相变及高阻尼特性。当锰含量超过 71% (原子分数 )时合金在变温过程中发生顺磁 反铁磁转变引起模量的剧烈变化。在尼尔点 (TN)以下的反铁磁状态～ 2 0 0℃温区内出现一个 10 -1数量级内耗的高阻尼区。随着含锰量的增加该区内逐渐显示出两个分立的内耗峰。确定了其中高温端的内耗峰为马氏体相变的贡献而低温端的内耗峰则纯属孪晶界的弛豫型内耗。文中测定了弛豫过程的激活能 。

The antiferromagnetic transition, martensitic transformation and high damping capacity of Mn-Fe-(Cu) alloys containing (45.9-86.4) at%Mn were studied by dynamic mechanical analysis and transmission electron microscopy. It was found that the elastic modulus is drastically anomalous around the Ne´el temperature TN when manganese content is more than 71 at%. Below the Ne´el point the antiferromagnetic state of the alloys shows itself a high damping capacity where the internal friction reaches the value with 10-1 magnitudes at the temperature range as wide as 200°C. Two distinct internal friction peaks are recorded in this region when further increasing manganese content. It was confirmed that one of the internal friction peaks at the higher temperature is attributed to the martensitic transformation and the other at the lower temperature pertains simply to the relaxation dissipation of micro-twin boundaries. The activation energy of the relaxation process was determined and the relationship between high damping capacity and the two transformations was discussed.