Fabricating In Situ Powdered Nickel–Alumina Metal Matrix Composites Through Microwave Heating Process: A Sustainable Approach

The microwave processing of materials is considered as a novel and sustainable process due to the unique heating properties, huge saving of energy and processing time and non-polluting characteristics. The purpose of the present work is to economically process nickel powder-based metal matrix composites reinforced with variable (5% and 10%) volume fraction of alumina powder through microwaves at 2.45 GHz frequency and 900-W power. The concept of microwave hybrid heating is used for heating and melting the nickel-based powders. Developed composites were characterized through phase analysis, microstructural characterizations, mechanical characterizations and wear study. The XRD analysis of alumina-reinforced composites revealed the formation of nickel aluminides (AlNi and NiAl 3 ), intermetallic of nickel such as Ni 3 Si and FeNi 3 , oxides of nickel and chromium carbides (Cr 3 C 2 , Cr 23 C 6 and Cr 2 C 3 ). Microstructures revealed formation of equiaxed grains with uniform dispersion of alumina reinforcements. The microhardness of composites was increased due to the presence of uniformly distributed alumina reinforcements and presence of intermetallics. Vickers microhardness for 10% alumina-reinforced MMC was 2.4 times higher than pure EWAC casting. The 10% ceramic reinforcement increased the tensile strength and wear resistance. For 10% alumina composite, wear was reduced by 71.67% in comparison with pure nickel-based casting. Graphic Abstract