Studies on Synthesis and Microstructure Evolution of Some Equiatomic High entropy Alloys

Abstract

The introduction of multicomponent alloy systems with equiatomic and near equiatomic compositions have caught the attention of the metallurgists for the last two decades, which have opened up avenues to create literally unlimited number of alloy systems based on the requirement of the application. This time is known to be one of the best times in the evolution of material science when man can design, evaluate and develop a number of novel alloy compositions based on the required application. One of the most interesting and perplexing feature of the concept of multicomponent alloy systems weather equiatomic or non-equiatomic, have the tendency to form simple solid solutions i.e. either an fcc, bcc or a mixture of fccand bcc and sometimes hcp as well, instead of forming complex structures with intermetallics or amorphous structures. Initial studies on the concept of the multicomponent alloy systems were mainly on the processing route which were the most conventionally known consolation methods like the vacuum arc melting and casting route and vacuum induction melting and casting route due to the ease in the manufacturing process. As there conventional processing routes attracted some limitations such as oxygen and carbon contamination, material loss and evaporation of some of the alloying elements whose melting points are lower than the temperature used during consolidation. Hence the birth of nanocrystalline processing technique where the alloying elements are made to bond at the atomic level by the energy imparted during mechanical attrition where coarse grained metal powders are milled in order to reduce their particle size. The particles exhibit a nanostructured nature in two way - one is, after of milling for few hours, the newline