Perspectives of recent developments in nickel base superalloys

Abstract

Developments of nickel base superalloys in this review is to study the latest trend of improvement with reference to high temperature performance and performances in aggressive media. The utilization of these alloys as candidate have well documented for thermal plants, atomic reactors, airways sectors and chemical plants. Castability attributes to in service ordered precipitation at high temperature described to understand the contemporary scenario. The effects of additional elements have always attempted to alloy without affecting the primary property requirements. Similarly welding have appeared to be improved by adopting inertia friction welding, transient liquid phase bonding or directly fabricating complex designed components by suitable hot isostatic pressing technique. However in case of joining methods the heat affected zone has always attempted to occupy thinner section zone. In oxidation, the developments have emphasized on oxygen scavenging elemental additions those induced dispersion of oxides in matrix and thin film formation for surface protection with out spallation of oxidized surface layers. The states of protection have also explained in response to applied stress associated so as to enhance crack formation. Hydrogenations of nickel base superalloys have referred to be highly accumulation oriented that enhanced embrittlement. Minimizations of grain boundaries have referred to improve the embrittling properties to approach to the single crystals.