Ultrasonic melt processing in the low pressure investment casting of Al alloys

AlSi7Mg investment cast test bars were produced using low-pressure die casting and ultrasonically refined during cooling. The microstructure and mechanical properties of the samples at different distances from the acoustic radiator were characterized for 650 degrees C pouring temperature. The combined technique lead to cast samples free from gas porosities and solidification defects, promoted the formation of small alpha-Al globular grains, modified the eutectic silicon, dispersed and decreased the size of intermetallic phases. The alloy mechanical properties were improved, increasing the ultimate tensile strength, yield strength and strain. (C) 2017 Elsevier B.V. All rights reserved.