α-Ti晶粒尺寸的EBSD技术测定方法及分析

Determination and analysis of α-Ti grain sizes by EBSD technique

用EBSD技术中的自动晶粒尺寸计算方法测定了六方结构α-Ti的晶粒尺寸。结果表明,对EBSD技术获取的数据,用面积法测量时能准确测出晶粒的平均尺寸。但EBSD方法测量晶粒尺寸时会受到标定率及误标的明显影响。影响最大的是伪对称性,即当因大量误标造成小"晶粒"出现时,平均晶粒尺寸明显降低。通过调整测试参数和后续处理可以去除该影响。比较不同级别降噪后的数据可知,标定率越高,降噪前后结果越接近;标定率越低,降噪前后差别越大。

Average grain sizes and grain size distributions of hexagonal α-Ti were determined by means of automatic calculation method in EBSD technique.The results showed that,Ti grain sizes can be effectively determined by the area-based method for grain size determination.However,grain sizes may be strongly influenced by indexing rate and mis-indexing due to pseudo-symmetry in EBSD measurement.The latter may lead to a large number of artificial mis-indexed small grains and significant reduction of average grain size.This phenomenon can be eliminated by setting proper measurement parameters in software or by post data processing.By comparing the original data with the data after noise reduction of different levels,it was observed that,when the indexing rate was high,the data before and after noise reduction were close to each other;when indexing rate was low,the data before and after noise reduction differed much.