Preparation And Characterization Of Al-Mg-B Thin Films By Magnetron Sputtering

AlMgBi4composite is a kind of nanometer materials, which possesses many excellent properties, such as high hardness, low density, low friction coefficient and so on. These excellent properties suggest that AlMgB14is an excellent candidate for protective coatings which can apply to cutting tools and micro-device components. It has a widespread application and prospect. At present work, the magnetron sputtering technology is employed to prepare Al-Mg-B thin films and the influences of deposition pressure and substrate negative bias voltage on the properties of thin films is studied. Otherwise, Al-Mg-B thin films were deposited on the soft metal aluminum and investigated the effect of boron sputtering power on the properties. The samples were investigated by electron microprobe analysis (EPMA),3D surface profiler, atomic force microscope (AFM), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nanoindentation to obtain the elemental contents, thickness, surface morphological structures, crystal structures and mechanical properties. The main research contents and results are as follows:(1) Al-Mg-B thin films were deposited by magnetron sputtering technology at different deposition pressure. After a set of test, we found that all the samples were stable amorphous structure. As the deposition pressure increased from0.3Pa to1.5Pa, the elemental contents were unaffected by the change of the deposition pressure. However, the surface roughness decreased gradually. The best Ra and RMS were about2.55nm and5.05nm, respectively. When the deposition pressure was0.5Pa, the thin films displayed the highest deposition rate and the maximum contents of B12icosahedra. The amorphous Al-Mg-B thin films showed the maximum hardness and Young’s modulus of35GPa and322GPa.(2) We explored the effect of substrate negative bias voltage on the properties of Al-Mg-B thin films prepared by magnetron sputtering. The substrate negative bias voltage changed from0V to200V. We found that all the samples showed a smooth surface. The proper substrate negative bias voltage could be conductive to the Al-Mg-B thin films with smoother surface. However, excessive substrate negative bias voltage induced the surface became coarse. The best Ra and RMS were about0.11nm and0.18nm, respectively. According to the tests, the B12icosahedra structure existed in the samples. We found all the samples represented the amorphous nature. When the substrate negative bias voltage was controlled at150V, the Al-Mg-B thin films displayed the maximum hardness and Young’s modulus of30GPa and289GPa.(3) Al-Mg-B thin films were deposited on the soft metal aluminum by magnetron sputtering technology. The crystal structure of films was investigated by X-ray diffraction. There were some characteristics diffraction peaks of the Al substrate but no obvious diffraction peaks corresponding to AlMgB14. The increase of boron sputtering power lead to decrease in surface roughness and rise in the deposition rate, hardness and Young’s modulus. When the content of boron in Al-Mg-B thin films was as high as95.4at.%, the Ra and RMS was as low as1.27nm and3.05nm, the hardness and Young’s modulus reached the maximum of22.7GPa and276GPa, respectively. Otherwise, it had a good adhesion strength between Al-Mg-B thin films and Al substrate. This experiment laid a great foundation of the future applications for the hard Al-Mg-B thin films deposited on the soft metallic materials.