材料期刊网

报道了从测量氧扩散峰高度的变化,来追踪氧在钼中的应变时效过程及其对屈服应力的影响。 含氧的钼丝无论是淬火时效或应变时效过程中内耗峰都逐渐降低以至消失。如对样品施以轻微的形变,则内耗峰又复出现。在交替进行形变和时效过程中,内耗峰可以更迭地消失和再现。 系统地研究了应变时效动力学及形变对内耗峰的影响,结果指出:(1)氧在钼中的应变时效动力学遵循由Harper修改过的Cottrell-Bilby的t~(2/3)关采式;(2)内耗峰高度随形变度的变化在2.5％伸长时具有一极大值;(3)在应变时效过程中,内耗峰的降低与屈服应力的提高相对应。 根据以上所得试验结果及分析,可以认为,内耗峰的降低与氧原子向位错周围分聚有关。基于这个假定,约略计算了位错密度及气团浓度。

Investigations have been carried out to study the process of strain ageing caused byoxygen in molybdenum by measuring the variation of the height of the internal frictionpeak with ageing-time. It was found that the peak height decreascs gradually and even-tually disappears with ageing-time both in quench-aged and in strain-aged specimens. Ifthe fully aged specimens were re-strained, the peak reappears immediately and its heightis higher than that of the quenched specimen. These processes may be repcatcd if thespecimens were further aged and strained. Systematic studies have been made on the kinetics of strain ageing and on the effectof deformation on the peak height. The results show that (1) the kinetics of strainageing follows Cottrell-Bilby's t~(2/3) relation; (2) the peak height increases with deforma-tion up to about 2.5％, and then decreases; (3) the decrease of the peak height cor-responds to an increase of yield stress. According to the above experimental results, it is believed that the decrease of thepeak height is associated with the segregation of oxygen atoms to dislocations duringageing. On the basis of this assumption, the dislocation density and the atmosphere con-centration were estimated.