高碳和低碳马氏体回火分解产物的共格性所引起的内耗峯

已往的研究结果指出,高碳和低碳马氏体在回火分解过程中分别在130℃和150℃出现一个内耗峯。本文根据内耗峯的出现和消逝的条件,较有系统地研究了高碳和低碳马氏体的回火分解和分解产物的形成和破坏,从而指出了这内耗峯确与分解产物与母体的共格性有密切联系。研究结果指出,无论在高碳或低碳马氏体的情形,这个内耗峯(内耗表示为温度的函数)的位置并不随测量频率的改变而改变,内耗峯的高度随着测量内耗时的应变振幅的增大而升高。这说明内耗峯并不是由于一种弛豫过程所引起的,这可能是所有的共格性内耗峯的一个特点。根据这一特点,认为内耗峯可能是由于共格界面在应力感生下的移动所引起来的。对于产生内耗峯的机构提出了初步看法。

INTERNAL FRICTION PEAKS ASSOCIATED WITH THE COHERENCY OF THE DECOMPOSITION PRODUCTS OF HIGH-CARBON AND LOW-CARBON MARTENSITE

Previous studies showed that internal friction peaks appear around 130℃ and 150℃ in the process of tempering of high-carbon and low-carbon martensite respectively. These peaks have been assumed to be associated with the coherency existing between the decomposition product and the parent phase. In the present work, systematic studies are made on the appearance and disappearance of the respective internal friction peaks in correlation with the formation and the destruction of the coherent decomposition products of high-carbon and low-carbon martensite.Results show that these peaks are definitely related with the coherency of the decomposition products.Experimental results show further that, in the case of high-carbon as well as low-carbon martensite, the position of the internal friction peaks (when expressed as a function of temperature) does not change with a change of the frequency of measurement, but the height of the peaks increases with a raise of the stress amplitude used in the measurement. This indicates that the observed internal friction does not involve a relaxation process, and this may be characteristic for all internal friction peaks associated with a coherency phenomenon. On the basis of the behaviour of the peaks, we may assume that the peaks are associated with the stress-induced movement of the coherent boundaries. The origin of the temperature variation of this internal friction is discussed.