Fe-Ni合金马氏体相变缺陷的正电子湮没研究

本文中用正电子湮没技术研究了Fe-Ni系合金的马氏体相变。实验结果表明,含镍量28.22—31.30wt％的六种退火态合金,正相变后,产生了大量的缺陷,使正电子湮没平均寿命及多普勒加宽线型参数S值分别约增加30％和20％。对28.93wt％Ni和31.30wt％Ni两种马氏体亚结构不同的合金,观测了正电子湮没参数与处理温度之间的关系,发现:缺陷主要产生在爆发马氏体形成阶段;在等时退火曲线上形成两个明显的台阶,是由于空位和位错恢复引起的。 关键词：

POSITRON ANNIHILATION STUDY OF DEFECTS IN MARTENSITIC TRANSFORMATION OF Fe-Ni ALLOYS

The martensitic transformation in thirteen Fe-Ni alloys has been studied by positron annihilation technique. The experimental results show that the values of the average lifetime f and the lineshape parameter S increase by about 30% and 20% respectively in six annealed and liquid nitrogen quenched alloys (28.22-31.30 wt% Ni). This confirms that the direct transformation produces a great number of defects in these alloys. The changes of the positron parameters with treating temperature have been determined in two different martensitic substructure alloys. It has been detected that the defects are chiefly produced in the stage of the burst martensitic transformation. Two distinct stages in the isochronal annealing curve confirm that the defects formed in the direct transformation mainly consist of vacancies and dislocations.