MICROSTRUCTURES AND PROPERTIES OF ELECTRONIC PACKAGING BOX WITH HIGH SILICON ALUMINUM-BASE ALLOY BY SEMI-SOLID THIXOFORMING

摘要

The electronic packaging box with high silicon aluminum-base alloy was prepared by semi-solid thixoforming.The flow characteristic of the Si phase was analyzed.Microstructures and properties of different parts of the shell were tested.The results show there exists segregation phenomenon between primary Si phase and liquid phase during thixoforming,the primary Si phase accumulates in the bottom of the box.The volume fraction of primary silicon phase decreases gradually along the bottom to the walls,accordingly the thermal conductivity of bottom and walls are 107.6W·m-1·k-1 and 131.5 W·m-1·k-1,the coefficient of thermal expansion(CTE) are 7.9×10-6K-1 and 10.6×10-6K-1 respectively,the flexural strength increases slightly from 167MPa to 180MPa.The microstructures and properties of the shell show gradient distribution overall.