马氏体时效钢的时效结构

本文利用透射电子显微相和电子衍射相对18Ni马氏体时效钢中沉淀强化相和时效结构的结晶学性质进行了研究。利用数个不同晶带的衍射相,一致地鉴别出同时存在Ni₃Mo,Ni₃Ti沉淀相和弥散的逆转变奥氏体,并且确定了它们相对马氏体基体的取向关系。证明了沉淀相、逆转变奥氏体与基体之间,密排面和密排方向都相互平行。指出在透射电子显微相中看到的魏氏型沉淀结构,实际上是由棒状沉淀相构成的三维空间格条结构,其中棒状沉淀相的长度方向平行于基体的四个〈111〉型方向。所观察到的扩张位错和位错塞积的真实性需要更多的实验证实。从结构观点,讨论了沿位错线的沉淀过程,并提出了钴钼交互作用的可能机制。

AGING STRUCTURE OF MARAGING STEEL

Transmission electron microscopy and electron diffraction studies were carried out in order to clarify the crystallographic properties of strengthening precipitates and aged structure in an 18Ni maraging steel.By using various zonal diffraction patterns, the co-existence of the precipitates Ni₃Mo, Ni₃Ti and the dispersed reverted austenite was identified, and their orientation relation-ships with respect to the martensite matrix determined.It was shown that the close-packed plane and direction of the precipitates and the reverted austenite are parallel to those in the matrix. The Widmanst?ttentype morphology in the transmission electron micrographs of the aged structure is in fact a three-dimensional skeleton structure in which the length direction of the rod-like precipitates is parallel to one of the four <111> directions of the matrix. The true existence of the observed extended and piled-up dislocations needs further experimental verifications.The process of precipitation along dislocation lines is discussed and a possible mechanism of the cobalt-molybdenum interaction is proposed from the structural point of veiw.