在线翻译

A typical optical microstructure of plasma nitrided specimen is shown in Fig. 6(a). It consisted of an internal nucleus of bainite plus martensite and a nitrided layer on the external surface. The nitrided surface consisted of two layers: a compound layer at the top, being very thin, and a diffusion layer beneath. In the diffusion layer a dispersion of nitride precipitates in the matrix enriched in nitrogen was observed; the layer, as delineated by the chemical etching, was homogeneous. The thickness of the diffusion layer increased with increasing nitriding temperature due to the higher diffusion rate of nitrogen at higher temperature. Fig. 6(b)−(d) shows the detail crosssectional images of plasma nitrided specimens revealed by scanning electron microscopy. In all the specimens, a compound layer was observed at the upper surface. As revealed by XRD, the compound layer was mostly comprised of the ε-nitride- and γ'-nitride phases. Nitriding at 475 °C resulted in the formation of a thin compound layer (Fig. 6(b)). On the specimens nitrided at 500 °C and 525 °C 更多：https://www.bmcx.com/ , the compound layer grew thicker and more homogeneous (Fig. 6(c) and (d)). The average thickness of the compound layers was measured to be about 2.8 μm, 4.2 μm, and 5.0 μm for the specimens nitrided at 475 °C, 500 °C, and 525 °C, respectively.