V-4Cr-4Ti/Ti复合材料界面的辐照损伤特性研究

Characterization of interface irradiation damage in Ti-clad V-4Cr-4Ti composite material

采用透射电子显微镜和纳米压痕技术研究了高能Fe10+离子注入后V-4Cr-4Ti/Ti复合材料界面辐照硬化、辐照缺陷以及微观结构的变化.根据样品成分和微观结构的特征,将该复合材料分成V-4Cr-4Ti基体、界面I、界面II和Ti基体四个区域.纳米压痕结果表明,辐照后样品均发生了辐照硬化,但界面处的辐照硬化远低于两基体,说明异质材料界面表现出了良好的抗辐照硬化能力.透射电子显微镜结果表明,辐照后界面处的辐照缺陷密度较小、尺寸较大、分布较均匀;而在两基体中辐照缺陷密度大、尺寸小且大量缠结.辐照后V-4Cr-4Ti基体、界面I区和界面II区均有一些富Ti析出物,但界面I的析出物数量和尺寸均高于界面II和V-4Cr-4Ti基体.由于Ti的析出改变了样品中局部的V/Ti比,导致界面I部分区域由b-Ti转变为a-Ti,形成a+b Ti共存区.

he development of electrically insulating coatings is extremely important for the lithium/vanadium(Li/V)blanket of the fusion reactor.However,Li/V cladding materials suffer many problems such astritiumpermeation and material corrosion.Thus,it is very important to find suitable insulating,tritium-resistant and corrosion-resistant coatings.So,the“V-alloy/Ti/AlN”bilayer coating was proposed by our groupin previous study for the first time.In this paper,the evolution of the hardness,irradiation defects andmicrostructure of the Ti-clad V-4Cr-4Ti composite material after Fe10+implantation are studied by transmissionelectron microscopy(TEM)and nanoindentation.According to the characteristics of the composition andmicrostructure,V-4Cr-4Ti/Ti composite material can be divided into four zones:V-4Cr-4Ti matrix,interface I(the interface near V-4Cr-4Ti matrix),interface II(the interface near Ti matrix),and Ti matrix.Thenanoindentation results show that radiation hardening occurs in all regions during irradiation.The radiationhardening in the interface is lower than in the V-4Cr-4Ti and Ti matrix.Thus,the interface of heterogeneousmaterial exhibits fine resistance to radiation hardening.The experimental values of hardness are much higherthan the values calculated by the dispersed barrier hardening model.One reason for the discrepancy is that thetheoretical values are calculated under the hypothesis of the uniform loop distribution.Actually,a large numberof dislocation loops accumulate and tangle with each other in the samples.In addition,the formation of theprecipitates is also one of the key factors.The TEM results show that the irradiation defects in the interface arelow in density,large in size,and uniform in distribution.As a contrast,high density,small size and twisteddislocation loops are observed in irradiated V-4Cr-4Ti and Ti matrix.These results indicate that the interfacecan play a critical role in the resistance to irradiation damage.Few tiny Ti-rich precipitates appear in the V-4Cr-4Ti matrix,while there are large quantities of Ti precipitates in the interface after irradiation.Moreover,the number and size of precipitates in the interface I are larger than those in the interface II due to theformation of a few V-rich precipitates in the interface I.The formation of precipitations changes the proportionof V/Ti,which leads to the transformation from b-Ti to a-Ti in the interface.