P K. Datta, H L. Du, J S. Burnell-Gray, Richard E. Ricker
In many applications of structural materials - aerospace, automobiles, power generation, etc., increasing demands are being made for materials with temperature capabilities greater than those of superalloys. Intermetallics with higher melting points can replace superalloys with inadequate melting points [1-3]. Intermetallics characterised by strong predominantly metallic bonding between unlike atoms sit between superalloys and ceramics. From bonding comes crystal structure, ordering, high strength at low and high temperature and low ductility. Low fracture strain and poor K1c of the intermetallics stem from their complex crystal structures, the large Burgers vectors, the high lattic stresses, the inadeuate slip systems, the inability to promote cross-slip, and the lack of grain boundary cohesion. The influence of such factors on thh corrosion behaviour is not insignificant. Stress generation during the scale growth, scale spallation during thermal cycling, stress corrosion and corrosion fatigue, and finally the cationic and anionic transports influencing the corrosion kinetics are all likely to be affected by these sub-structure defects. Thus the corrosion behaviour of the intermetallics stems from their inherent immunity or susceptibility to corrosion and from the modifications in macroscopic parameters such as grain size, stoichiometry, grain boundary design, micro-alloying, second phase incorporation to increase the number of slip and to hence confer improvement of K1c and fracture strain.
, Du, H.
, Burnell-Gray, J.
and Ricker, R.
Corrosion of Intermetallics, To Be Determined, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=853340
(Accessed December 7, 2023)