Properties Of The Metallic Glasses At Extreme Enthalpy States

Owing to the disordered structure,the metallic glass shows with unique mechanical and functional properties including high strength,large elasticity,soft magnetic properties and corrosion resistance.Limitation to the characterization and analysis methods for the disordered structure,the relationship between the structure and properties is still unclear.In another aspect,energy,as well as enthalpy,is one of the most essential parameters to analysis properties and theory for the meta-stable materials.Depending on the cooling rates,metallic glasses lie in different energy states,and the energy states dominate the performance of the materials.With the increase of the energy,structure relaxation,accompanied with the decrease of the plasticity,increase of the hardness and density,occur inner of the material;the increase of the energy,also termed as rejuvenation could induce the increase of the plasticity and decrease of the density.Investigation of the theory and properties for the metallic glass at extreme energy states could shed the light of the nature for the glass state material and pave the way for the development of the novel materials with extraordinary properties.In this work,we have achieved the fabrication both of the high and low energy states metallic glass and found the abnormal relaxation behavior in these materials.Low-energy metallic glass film with high thermal stability was achieved by the ion beam assisted deposition method under mild temperature.Multiple functions were found for this metallic glass film.It has enhanced thermal stability(onset of crystallization temperature increased by 59K),large area(over than 100 cm2),flexibility,reflectivity and atomic smooth surface.This film favors the applications including smart skins and wearable devices.The method of controlling the deposition rate to achieve high thermal stability paves new way to develop novel materials.High-energy metallic glass ribbon was achieved by chemical treatment on the surface.Treated with alkaline solution,a predominant rejuvenation effect with both tensile ductility and compressive plasticity enhancement can be achieved.The impact depth of this method is inner the 10 ?m on the surface and could have 86% energy conversion efficiency which is much higher than the conventional severe plastic deformation methods.This method enlightens us a new approach to achieve novel material with better properties.The abnormal relaxation behavior was found in the extreme energy states metallic glasses.For the low-energy metallic glass,the non-monotonous relaxation was found.The surface Young's modulus,characterized by the bi-mode AFM shows three processes with the increase of the annealing time.It is suggested that the anti-free volume rather than the general free volume dominates the relaxation process in this film.For the high-energy metallic glass,opposite evolution in the relaxation spectrum was found.We achieved the metallic glass with extreme energy states and found the abnormal relaxation behavior in these materials.This work shows the detail energy structure for the meta-stable material at extreme energy states and helps us to learn the nature of the glassy material.