The Influence Of Liquid Structure Evolution On Properties Of Metallic Glasses

Due to its unique properties that differ from conventional crystalline metal materials,metallic glasses are gaining more and more attention from researchers.The properties of metallic glass solids are largely influenced by the structure of the melt due to the liquid-solid inheritance phenomenon.Therefore,the research related to the structural evolution of metallic glass systems during high temperature the high temperature melt and cooling process has been a hot topic in the field of metallic glasses.The liquid-liquid structure transition,as an anomalous structural transition behavior found in the high temperature liquid and the supercooled liquid of the metallic glasses in recent years,is still not clear how it affects the properties of metallic glasses.It is important to solve this problem in order to better understand the liquid structure evolution of metallic glasses and to control and predict the properties of metallic glasses more precisely.Based on the above background,this paper improves the accuracy of analyzing melt structure changes through viscosity by investigating the factors influencing viscosity data measurements;using the liquid-solid inheritance of metallic glasses,the liquid-liquid structure transition behavior in the multi-path of CuZrAl metallic glasses is discovered and its influence regulation on the solid properties of metallic glasses is discussed.The main research contents and conclusions are as follows:(1)Viscosity measurement samples of CuZr binary alloys were used to analyze the reasons for the influence of crucible inner surface morphology on the viscosity data results in terms of chemical reaction and wettability differences.The experimental results show that the difference in roughness of the inner surface of the crucible affects the wettability between the CuZr melt and the crucible under the premise of non-reactive wettability.An increase in the roughness of the inner crucible surface deteriorates the wetting with the sample melt,leading to smaller viscosity data results.The phenomenon of scouring of the crucible by the melt due to long oscillation times was found and it has an effect on the viscosity data.This result provides a new experimental method to obtain accurate viscosity data,which can facilitate the work related to the study of melt structure by viscosity.(2)The liquid-liquid structural transition behavior in the high-temperature liquid of CuZrAl metallic glass was discovered by kinetic viscosity.The melt structure before and after the liquid-liquid structural transition was frozen into the metallic glass ribbons by single roller melt spinning,and the regulation of its influence on various properties such as thermal stability,glass-forming ability and mechanical properties of metallic glasses was analyzed to investigate the structural origins that lead to different trends of property changes before and after the structural transition.The results show that the liquid-liquid structural transition behavior leads to a significant increase in the thermal stability and glass-forming ability of CuZrAl metallic glasses.In terms of mechanical properties,the hardness and modulus of the samples before and after the liquid-liquid structural transition show a tendency to decrease and then increase with increasing Tq temperature due to the change in the dominant structural origin.This finding provides a new thinking for the work related to the improvement of metallic glass properties through melt structure modification,which can be a promotion to the development of highperformance metallic glasses.(3)The possibility of liquid-liquid structure transition in the cooling process and in the subcooled liquids region of CuZrAl metallic glasses was investigated by varying the cooling rate and isothermal annealing treatment.The effects of the liquid-liquid structure transition on the glass-forming ability and mechanical properties were analyzed by means of the DSC and instrumented nanoindentation.The results show that the liquid-liquid structure transition exists in CuZrA1 metallic glasses during cooling and within the subcooled liquid phase,and that this phenomenon leads to an increase in their glass-forming ability and a decrease in hardness.This result has positive implications for investigating the prevalence of liquid-liquid structure transition of metallic glass systems in different paths,and provides new ways to improve the stability of metallic glasses and the development of new high-performance metallic glasses.