高温淬火Co72.7C11.8Si15.5磁性合金 的结构和相转变

摘要

The structure and phase transformation were inv estigated for Co72.7C11.8 Si15.5 alloy homogenized at 1000 ℃ for 7d, then qu enched in water by means of X- ray diffraction， TEM， FESEM and EP. The alloy consists of both hcp-Co as ma trix (a=0.2505nm，c=0.4073nm) and hexag on al graphite as the second phase(a=0.2465nm， c=0.671 1nm). No (200) reflection of fcc-Co high temperature phase is det ect ed， which shows that the phase transformation from fcc to hcp has been complet ed, an d the transformation temperature in equilibrium is over 1000℃. Stable hcp-Co alloy is readily obtained by adding C and Si elements into Co metals.%用X射线衍射、透射电子显微镜、场致发射 扫描电镜和电子探针研究了Co72.7C11.8 Si15.5合金在1000℃均匀化退火7d后，水淬至室温的相变和相结构。结果表明：合金由两个相组成，一个是具有密排六方(hcp)结构的基体Co固溶体，其晶格常数a=0.2505nm，c=0.4073nm；另一个是具有六方(hex)结构的第二相石墨，其晶格常数a =0.2465nm，c=0.6711nm。X射线衍射没有探测到高温fcc-Co相的(200)衍射峰，表明fcc-Co相已完全转变为hcp- Co相，平衡转变温度在1000℃以上。在Co金属中复合添加C和Si元素可 以容易地获得室温稳定的hcp结构。