不同速度拉伸变形时高纯铁的正电子湮没研究

本文采用慢拉伸与正电子多普勒展宽方法相结合,研究应变速率对正电子S参数与形变量ε变化规律(S-ε曲线)的影响,获得如下结果:1)高纯铁慢拉伸条件下,其S-ε曲线出现不饱和现象,应变速率越小,不饱和现象越明显;2)高纯铁中S-ε曲线随应变速率变化的原因归结于不同应变速率拉伸所产生的位错组态不同;3)高纯铁拉伸变形时,S参数的增加一部份来源于位错,另一部份来源于空位,空位及其聚合物是导致S-ε曲线不饱和的主要原因。关键词：

POSITRON ANNIHILATION STUDY ON DEFORMATION OF HIGH PURITY IRON UNDER DIFFERENT STRAIN RATE

Variation of S-parameter with the strain (S-ε curve) under different strain rate are investigated by combining Doppler broadening measurement with slow tensile test. Experimental results are as follows:1. Under slow strain rate, the S-ε curve in high purity iron does not tend to saturation. The slower the strain rate is, the more evident the "non-saturation phenomenon".2. Variations of S-ε curve with strain rate are attributed to the different configuration of dislocation distribution under different strain rates.3. As high purity iron is deformed, the increment of S-parameter depends not only on dislocation density but also on vacancy concentration, and we attibute the so called "non-saturation phenomenon" of S-ε curve to the strain induced vacancies.