抗菌时效处理对含Cu双相不锈钢组织和性能的影响 Ⅰ.富Cu相的微观结构及演变规律

EFFECTS OF ANTIBACTERIAL AGING TREATMENT ON MICROSTRUCTURE AND PROPERTIES OF COPPER-CONTAINING DUPLEX STAINLESS STEELⅠ.Microstructure and Evolution of Copper-Rich Phase

采用SEM,XRD以及TEM对经抗菌时效处理后的含Cu双相不锈钢中抗菌富Cu相的微观结构及析出演变规律进行了研究.结果表明,在540 - 580℃温度范围内.双相不锈钢中的铁素体基体及α/γ相界上均有抗菌富Cu相析出,奥氏体内没有新相的析出;随时效时间的延长,析出相逐渐粗化,并由球形颗粒状转变为棒状或长条状;随着时效温度的提高,富Cu相析出速率加快,较快地由颗粒状转变为棒状;时效处理过程中,富Cu相会随时间的延长及温度的提高从亚稳态过渡到稳定的ε-Cu相;ε-Cu相具有复杂的多层孪晶结构,与铁素体基体满足Kurdjumov- Sachs取向关系:(111)_(ε-Cu)∥(110)_(α-Fe),[011]_(ε-Cu)∥[001]_(α-Fe),(111)_(ε-Cu)∥(121)_(α-Fe),[011]_(ε-Cu)∥[012]_(α-Fe).

Nowadays, the events of bacterial infection are increasingly arising. It is urgent to develop new antibacterial material to fight against the bacteria having resistance to drug. Because the antibacterial stainless steels have both antibacterial property and other excellent combination ones, their development has been obtained rapidly. At present, the copper-containing antibacterial stainless steels are the research focus. It has been reached that the antibacterial effect of those materials is due to the copper-rich phases precipitated from the matrix by aging treatment. Most of studies were performed at single-phase stainless steels, but rarely at duplex stainless steels. It is necessary to study the precipitation process of copper-rich phases in duplex stainless steels for the development of antibacterial duplex stainless steels. In this work, the microstructure and precipitating evolution law of copper-rich phases in the copper-containing duplex stainless steels during antibacterial aging treatment has been analyzed in detail by SEM, XRD and TEM. The results indicate that antibacterial copper- rich phases are precipitated from ferrite and α/γ interfaces, no precipitation in austenite when the duplex stainless steels are aged at temperature ranging from 540 to 580℃. The technique parameters of the aging treatment have important effect on the volume fraction and morphologies of precipitated phase. With aging time increasing, the precipitates coarsen, and their morphologies gradually change from spherical particle to rod-like or long-stripe like grain. When the aging temperature is raised, precipitation speed of copper-rich phases accelerates and they make the change like before. At the same time, the copper-rich phases gradually turn from metastable state to steady ε-Cu phase with the composition close to pure copper, which has complicated multilayer structure with twisting layers. The Kurdjumov Sachs orientation relationships between ε-Cu phases and the ferrite matrix followed： （111）ε-Cu//（110）α-Fe,（011）ε-Cu//（001）α-Fe,（111）ε-Cu//（121）α-Fe,（011）ε-Cu//（012）α-Fe.