纳米晶合金中缺陷总体变化的多普勒湮没能谱初步研究

A Preliminary Study of Evolution of Defects in Nanocrystalline Alloys by Doppler Broadening

用正电子湮没多普勒展宽能谱测量和分析了若干急冷淬火制备的薄带,表明软磁Fe基纳米晶合金中的缺陷(自由体积)远多(大)于其晶化前的非晶态;能够晶化成纳米晶的Fe基非晶制备态材料中的缺陷也多(大)于类似成分但又不能晶化成纳米晶的非晶态材料中的缺陷;Fe_(73.0)Cu_(1.0)Nb_(1.5)Mo_(2.0)Si_(13.5)B_(9.0)合金的急冷淬火制备态在热处理过程中,低温退火时缺陷减少,高于200℃的退火导致缺陷增加,纳米晶化后的进一步退火缺陷基本不增加;Fe_(73.0)Cu_(1.0)Nb_(1.5)Mo_(2.0)Si_(13.5)B_(9.0)合金纳米晶化后,在所选定的测量条件下没有发现正电子湮没参数随时间、温度的变化,说明该材料缺陷结构相当稳定。

A number of the ribbons by the melt spinning technique have been studied using Doppler broadening of positron annihilation. It is shown that the defects (free volumes) in the nanocrystallized ribbons of soft magnetic Fe-based alloys were far more than (greater) those in its as-quenched ribbons. Also, the defects in the as-quenched Fe-based amorphous ribbons which are able to be nanocrystallized were more than those in the amorphous ribbons which are not able to be nanocrystallized, although there is a little difference in their alloying elements. During the annealing of the as-quenched ribbons of Fe_(73.0)Cu_(1.0)Nb_(1.5)Mo_(2.0)Si_(13.5)B_(9.0) alloy, the defects decreased below 200℃, increased at a higher temperatures, and did not increase basically after nanocrystallization. The ribbons of Fe_(73.0)Cu_(1.0)Nb_(1.5)Mo_(2.0)Si_(13.5)B_(9.0) alloy having been nanocrystallized, there was not a remarkable change of S-lineshape parameter with the annealing temperature and time under the selected experimental conditions, indicating that the structural defects are quite stable.