According to the results of the study of Warwick Aluminum experts, 1 xxx alloy aluminum foil blank in the middle of the process of the existence of the best solution dilution point phenomenon, that is, aluminum matrix impurity element Fe, Si content in a certain annealing time to achieve minimal Value, when the holding time is lower or higher than this point, the solid solubility increased. Combined with the results of tissue analysis and x-ray phase analysis, this phenomenon can be explained as follows.
In the intermediate annealing at 380 ℃, there are two processes which have the opposite effect on the change of the solid solubility, and one is the precipitation of the αc (A1FeSi) phase, which reduces the solid solubility of the impurity elements Fe and Si in the Al matrix The other is the phase change reaction βp (A1FeSi) - αc (A1FeSi), this process to Fe, Si solid solubility increased. The solid solubility of Fe and Si elements in the Al matrix during the intermediate annealing process is the result of the combined action of these two processes. When the intermediate annealing time is short, the precipitation of αc (AIFeSi) phase plays a major role