Effects of Cu and Mg alloying on the microstructure and properties of Al–12Si alloy prepared by spray forming

Al–12Si alloys for electronic packaging shell were prepared by spray forming followed by hot pressing and the effects of 0.5%Cu and 0.6%Mg alloying on the microstructure, thermo-physical, and mechanical properties were examined. The microstructural observations show that Al₂Cu, Mg₂Si, and β″ phases were formed in the matrix by adding Cu and Mg. With the addition of Cu and Mg, the strength and hardness of the Al–12Si alloy increase from 154 to 234 MPa, and 55 to 75 HV, respectively, with an increment of approximately 51.9% and 36.3%. The strengthening effect is attributed to the combination of solution strengthening and precipitation strengthening. Compared with the unmodified alloy, the coefficient of thermal expansion of the modified alloy is increased slightly while the thermal conductivity is decreased slightly. Consequently, the alloying route of Al–12Si alloy is feasible for electronic packaging application.