Mechanical Properties Test And Numerical Simulation Of Interface Structure In The Chromium Matching Metal Films

With the rapid development of economy and society in the world, the electrical and electronic devices develop to a higher performance, multi-function, higher speed and the information processing ability is improved quickly. All of these must continue the equipment system towards large-scale, large capacity and maximization directions. But, on the other hand, the units, parts and the materials of the system must be designed to light weight, thin structure, short calculating period, small volume and many other characteristics. To meet these requirements, the materials and process of metal nanometer films develop quickly. Among them, the bilayer films which structure is different from the single film have many nice properties. There are higher hardness, friction and wear properties in the bilayer films. And even more, they can improve the toughness, resistance to crack extension and thermal stability of the coating. So, more and more researchers study of the structure and mechanical properties of the bilayer films at the nanometer scale.In this paper, Cu/Cr bilayer films, Cr/Al bilayer films, W/Cr bilayer films and Al/Cr bilayer films are prepared by using the magnetron sputtering. And their microstructure and mechanical properties are also studied. Based on the nano-indenter experiment of Cr/Al bilayer films, the finite element analysis is used to simulate the experiment. Totally, the following parts are investigated:1. Cu/Cr bilayer films, Cr/Al bilayer films, W/Cr bilayer films and Al/Cr bilayer films are studied in the nano-indenter experiment. Their elastic modulus value and hardness value are obtained from the experiment. Test results show that the elastic modulus and hardness of the bilayer films vary with the indent depth in accordance to a certain rule. The structure of the interface in the films and between the films and the substrate are studied according to the rule. Effects of the thermal cycling on the mechanical properties of the Cu/Cr bilayer films and the Al/Cr bilayer films are also studied. To the Cu/Cr bilayer films, the elastic modulus value and the hardness value are higher after the thermal cycling. But the effect is opposite to the Al/Cr bilayer films.2. W/Cr bilayer films and Cr/A1 bilayer films are studied in the nano-indenter experiment. The interfacial binding forces in the films and between the films and the substrate are obtained. Compared to the test results in the nano-scratch before and after the thermal cycling, the interfacial binding forces in W/Cr bilayer films can be decreased. But the interfacial binding forces in Cr/A1 bilayer films can be improved after the thermal cycling which can form a nice interface structure between each composition film.3. Based on the nano-indenter experiment of Cr/Al bilayer films, FEA method is used to simulate the experiment. It can be known that the maximum stress is mainly centralized nearby the indenter. And the stress is mainly centralized in the bilayer films which will protect the substrate. From the simulation, the stress value in the Y direction in the interface and on the surface of the bilayer films is becoming smaller when the distance in the X direction is far away from the indenter. And the stress value in the Y direction below the indenter increases slowly at first and decreases linearly later when the distance in the Y direction increases.