Perspectives of recent developments in nickel base superalloys

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.