碳在面心立方系合金钢与金屬中微扩散所引起的内耗峰

用扭摆作内耗测量,发现了几种面心立方系合金钢(18/8型不锈钢及高锰钢)中含碳可以引起内耗峰。当振动频率约为每秒1周时,峰的巅值温度在200-300℃之间。当钢中固溶体的碳量增多时,内耗峰升高而峰的位置移向低温,当钢中所含的碳因回火而发生沉淀时,内耗峰降低而峰的位置移向高温。把内耗方法所测得的激活能、弛豫时间和由此计算所得的扩散系数与资料上所载的碳在面心立方系的钢中宏观扩散的数据相比较,指出所观测的内耗峰确是由于碳在钢中的微扩散所引起来的。用同样的实验方法也发现了碳在镍铝合金及在纯镍中由于微扩散而引起的内耗峰。这些实验指出,碳在面心立方系晶体中微扩散而引起内耗峰这件事实,可能是一种普遍的现象。

INTERNAL FRICTION PEAKS ASSOCIATED WITH THE STRESS-INDUCED DIFFUSION OF CARBON IN FACECENTERED CUBIC ALLOY-STEELS AND METALS

Internal friction peaks asscciated with the presence of carbon in several types of f.c.c. alloy-steel (18/8 type stainless steel and high manganese steel) have been observed from measurements with a torsion pendulum. The temperature for maximum internal friction lies between 200-300℃with a frequency of vibration of about I cycle per second. The height uf the peak rises and the position of the peak shifts to a lower temperature with an increase of the carbon content. When the amount of carbon in solid solution is reduced by tempering the specimen at an elevated temperature, the height of the peak lowers and the peak shifts to a higher temperature. A comparison of the activation energy and the diffusion ccefficients determined by internal friction methods with those measured in conventional macro-diffusion experiments reveals that the observed internal friction peak is associated with the stress-indused diffusion of carbon in these face-centered cubic steels.Internal friction peaks associated with the stress-induced diffusion of carbon in a Ni-Al alloy and in pure nickel have also been observed. These experiments show that the appearance of an internal friction peak associated with the diffusion of carbon in f.c.c. metals may be a general phenomenon.