Microstructural characteristics and tensile properties of in-situ and ex-situ microwave casts of Al-7039 alloy

Abstract

Casting is the preferred primary manufacturing process for many industrial components as it offers processing flexibility and economy. Use of microwave energy for casting is usually motivated by time compression, eco-friendly and energy-efficient processing. The present work examines the effect of pouring and solidification conditions on the properties of in situ and ex situ microwave casts of Al-7039 alloy. Melting of the alloy was carried out inside the applicator using 2.45 GHz microwaves at 1400 W; pouring and solidification were accomplished in a graphite mold using the in situ and ex situ casting approaches. Microstructural characterization of the casts revealed that finer grains and dense casts were obtained through the in situ approach. Pouring and solidification conditions affect grain structure and intermetallic phases. Improvement in tensile properties of in situ casts was observed due to the presence of finer intermetallic phase Al8Fe2Si; whereas, copper-based intermetallic phases in ex situ cast deteriorates its strength.