Elimination of Shrinkage Cavities by Liquid Hot Isostatic Pressing in Aluminum Alloys under Superplastic Conditions

The liquid hot isostatic pressure in superplastic conditions was applied to eliminate macroporosity in a die cast Al-12%Si eutectic alloy. The removing of macroporosity provides the yield stress increase of 56%, the ultimate tensile strength increase of 46%, the total elongation increase of 21%, the fracture toughness increase of 340% and the fatigue strength increase of 58%. Remarkable improvement of mechanical properties is caused by suppression of crack initiation on internal coarse pores.

Microstructural and Mechanical Properties of Al 7003 Alloy Processed by Dual Equal Channel Lateral Extrusion

In this paper, the Al 7003 alloy in the as-annealed condition was processed by dual equal channel lateral extrusion (DECLE) at room temperature. The microstructure and mechanical properties of the as-annealed and DECLEed alloys were examined. The results showed that the microstructure of as-annealed Al 7003 alloys was refined by the formation of deformation bands, with dislocation cells and subgrains inside these bands. The final grains with an average size of about 250nm are observed. Due to DECLE, tensile yield strength and ultimate tensile strength increase by 84.5%, 35.4%, respectively. Meanwhile, elongation to failure decreases by 40.4%. The fracture was characterized by ductile fracture due to existence of a large number of dimples.