Microchemical Evolution in Alloys by Ion Irradiation and Fundamental Research for Creation of New Materials

用能量色散X射线能谱(EDS)分析了离子辐照合金的微观化学演化。在高温重离子辐照奥氏体钢中，观察到合金元素的非平衡偏聚或贫化。镍和硅在空洞和晶界附近富集区，而铬、锰和钼则在那里贫化。这些都是由这些元素的尺寸系数来解释的。热控材料中未见的富镍相影响着辐照过程中的组织演变。奥氏体钢中的MC析出物在辐照过程中具有很强的稳定性，而Ni和Si在其表面的偏聚可以改变析出物。离子辐照合金的组织和微观化学演化强烈地依赖于注入离子的种类和能量。例如，400HEV P离子辐照奥氏体钢，在离子深度附近产生磷化铁，这些析出物抑制辐照下空洞的形成；离子辐照沉淀硬化铁素体钢，促进马氏体相向奥氏体相的转变，这是热时效所没有的。离子辐照时，各种合金中存在非平衡偏析和析出。从这项研究中提取了大量数据来控制高能离子辐照产生新材料的过程。

Microchemical evolution in ion-irradiated alloys is analyzed by energy dispersive X-ray spectroscopy (EDS). Non-equilibrium segregation or depletion of alloying elements is observed in austenitic steels irradiated with heavy ions at elevated temperatures. Ni and Si are enriched around cavities and grain boundaries, while Cr, Mn and Mo are depleted there. These are explained by size factors of these elements. Ni-rich phases which are not seen in thermally controled material affect microstructural evolution during irradiation. MC precipitates in austenitic steels have strong stability during irradiation, while segregation of Ni and Si to their surface can modify the precipitates.Microstructural and microchemical evolution in ion-irradiated alloys strongly depends on both energy and species of injected ions. For example, 400 HeV P^+ ion irradiation to austenitic steels produces iron-phosphide around the depth of ion range, and these precipitates supress void formation under irradiation.Ion irradiation to precipitation-hardened ferritic steel promotes transition of martensitic phase to austenitic phase, which is not observed by thermal aging.Non-equiliburium segregation and precipitation are found in various kinds of alloys during ion irradiation. Enormous data to control the creation of new materials by irradiation with energetic ions have been extracted from the present study.