Microstructure Characteristics Of Al Monotectic Alloy Melts

The structure and physical properties of alloy melts have important influence on the performance and structure of solid materials. The study of properties stresses on the resistivity, viscosity, density, surface tension, etc. The resistivity and viscosity reflect transport properties of atoms and electrons respectively and are of sensitivity to the microstructure and macrostructure of liquid alloy. It is important and essential to investigate the structure of liquid alloy baseed on physical properties.In this work, the processing program for resistivity was compiled with Excel VBA. It accomplished Automatic-data-processing and significantly improved processing efficiency and accuracy. The resistivity of Al, Bi, In and Al-In, Al-Bi liquid alloy was studies by DC four electrode method. The resistivity for Al, Bi, and In appear discontinuous change at temperatures from(1348 to 1453) K,(1049 to 1344) K, and(1071 to 1218) K respectively and are consistent with the thermodynamics and kinetics characteristics. Their characteristics are Irreversible, Irreversible and reversible respectively. Compared with continuous heating, the resistivity curve of In melt is linear in stepped heating. It shows that there are metastable structure which disappear after two hours insulation.The viscosity of Al, In, Al98In2, Al97Bi3 was studied using an oscillating cup viscometer. It shows that the viscosity for Al, In, Al98In2 and Al97Bi3 occur discontinuous change at temperatures from(1014 to 1089) K,(1152 to 1224) K,(663 to 783) K and(1023 to 1273) K respectively. The transition temperature range of monotectic alloys correspond to miscibility gap, in which momentum exchanges significantly contribute to viscosity. The melt has higher viscosity, activation energy for viscous flow and smaller flow unit volume under magnetic field. Lorenz force obstructs the melt convection and bound vibration of atoms which is equivalent to reducing the temperature of the melt. The flow unit volume becomes smaller, which is negative feedback to external magnetic field. The density of Al95In5 melt was studied with high temperature melt density measuring instrument. It shows that there is an abnormal change at miscibility gap which is relevant with the interaction of Al-Al, Al-In, In-In.Through the research on structure of rapidly solidified alloy, shows that there are mainly three kinds of basic structure: random structure, core-shell structure, dispersion structure. In fact, the c structure of monotectic alloy is composite of three kinds of different levels.