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用高分辨电子显微镜(HREM)进行了Nb、Cr、Mo、Ni等微合金元素复合微合金化的实用超低碳含Cu钢中时效析出相的形貌观察及晶体结构鉴定,探索将HREM分析技术有效应用于工程材料微观结构研究的新途径。在300万倍以上的放大倍率下清晰观察到了尺寸仅有十个nm左右的细小弥散分布的时效析出颗粒以及其中的孪晶结构,还有大量在局部微区形成的过渡结构。尝试用单个颗粒HREM像上的晶格条纹间距鉴定了钢中除ε-Cu以外的另3类时效析出相的晶体结构。结果表明,时效期间钢中析出Cu、Nb、Cr、Mo、Ni的特殊碳化物(碳氮化物),与ε-Cu共同产生时效强化作用。提出了用HREM像对实用钢材中弥散分布的微细析出相进行晶体结构鉴定的实验方法。
Morphology and crystal structure of the precipitated phases in practical ultra-low carbon Cu-containing steels microalloyed with microalloyed elements such as Nb, Cr, Mo and Ni were investigated by high resolution electron microscopy (HREM) Technology is effectively applied to the study of the microstructure of engineering materials, a new way. At the magnification of more than 3 million times, the precipitated particles with fine and dispersed size of only about 10 nm and the twin structures therein are clearly observed, and a large number of transitional structures are formed in the local micro-regions. Attempts to identify the crystal structure of the other three types of precipitated phases other than ε-Cu in the steel by the lattice fringe pitch on the single particle HREM image were examined. The results show that the special carbides (carbonitrides) of Cu, Nb, Cr, Mo and Ni precipitated in the steel during aging are combined with ε-Cu to produce the aging strengthening effect. In this paper, an experimental method for the crystal structure identification of finely precipitated phases dispersed in practical steel by HREM is proposed.