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低合金铁素体钢样品经880℃加热0.5 h后水淬,再在660℃调质处理10 h,最后在400℃进行等温时效处理11000 h后,利用高分辨透射电镜(HRTEM)和能谱仪(EDS),分析低合金铁素体钢中析出的纳米富Cu相的复杂晶体结构。观察到长轴约13.3 nm,短轴约8.9 nm的具有典型鱼骨状条纹特征的两单斜9R结构,且互为孪生关系,密排面(009)与孪晶界()的夹角约为62.7°,同时9R孪晶结构内部存在严重的晶格扭曲和大量的层错,且有向9R多重孪晶结构转变的趋势,说明单斜9R孪晶结构是一种不稳定的过渡相;还观察到另一个单斜9R孪晶结构的纳米富Cu相中,局部区域存在非孪晶的单斜9R结构,且9R非孪晶结构的密排面(009)是由9R孪晶结构的孪晶界()转变而来,这可能是由9R孪晶结构内部严重的晶格扭曲和大量的层错产生较高能量导致。说明纳米富Cu相在不同晶体结构演化过程中的复杂性。
Low-alloyed ferritic steel samples were quenched by heating at 880 ℃ for 0.5 h, then quenched and tempered at 660 ℃ for 10 h, and finally isothermal-treated at 400 ℃ for 11,000 h. High-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) to analyze the complex crystal structure of nano-Cu-rich phase precipitated in low-alloy ferritic steel. Two monoclinic 9R structures with a typical fishbone-like stripe pattern with a long axis of about 13.3 nm and a short axis of about 8.9 nm were observed and mutually twinned. The included angle between the cataract surface (009) and the twin boundary Is 62.7 °. At the same time, there is a serious lattice distortion and a large number of faults in the 9R twin structure, and the tendency of the 9R twin structure changes. It shows that the monoclinic 9R twin structure is an unstable transition phase. It is also observed that in the monoclinic 9R twinned nano-Cu-rich phase, the non-twinned monoclinic 9R structure exists in the localized region and the close-packed plane (009) of the 9R non-twinned structure is composed of 9R twins The twin boundary () transition, which may be caused by the severe internal lattice distortion in 9R twins and the high energy generated by a large number of faults. Explain the complexity of nanocrystalline Cu-rich phases in the evolution of different crystal structures.