Experimental And Theoretical Study On Hardening Mechanism Of Double Crystal Materials Under Ion Irradiation

Irradiation defects will seriously affect the mechanical properties of materials,and radiation hardening is one of its main forms.The special interface structure of bicrystal materials has good defect absorption,so it is of great significance to explore the radiation damage effect and analyze the hardening behavior and physical mechanism of bicrystal materials.In this paper,the hardness model of bicrystal material is established,the experimental data of bicrystal copper material are compared with the theoretical results,and the rationality of the model is analyzed.The main work includes the following aspects: The main results are as follows:(1)The preparation methods of double crystal materials are compared and the test methods are determined.Firstly,the existing models of ion irradiation hardening are briefly summarized,and the radiation damage effect and the structural characteristics of interface materials are briefly described.Then,according to the preparation of double crystal materials,the advantages and disadvantages of different preparation methods are compared and analyzed.Finally,the double crystal material was prepared by magnetron sputtering method,and the mechanical properties of the double crystal material were tested by nano-indentation method.(2)The hardness model of bicrystal materials without irradiation is proposed.In this model,the influence of grain boundary on the configuration and expansion law of plastic region in the process of nano-indentation experiment is considered,and a theoretical model of hardness varying with indentation depth is established.According to the influence of grain boundary,the whole nano-indentation process is divided into four stages.The related parameters of bicrystal copper samples are fitted by the experimental results of nano-indentation,and the fitting and prediction results of the model are in good agreement with the relevant experimental data,and have good prediction accuracy.(3)A theoretical model for the variation of hardness of bicrystal materials with indentation depth under ion irradiation is proposed.The model systematically analyzes the different hardening mechanisms of bicrystal materials under ion irradiation,and considers the interface effect and irradiation effect at the same time.The evolution of plastic zone,average irradiation defect density and average geometric necessary dislocation density in the whole nano-indentation process is quantitatively analyzed.It is found that the grain boundary affects the dislocation density and defect density by affecting the configuration and expansion rate of the plastic region,and finally affects its contribution to hardness.This method can be used as a reference for the analysis of other mechanical properties of bicrystal materials under ion irradiation.