The sliding wear behaviour of reactively hot pressed nickel aluminides
has been studied. The influence of load and intermetallic stoichiomet
ry on wear rate has been considered using a block-on-ring test method
with 440C as the counterface material. The results show that wear rate
increases linearly with load and decreases as the nickel content incr
eases. Stoichiometric NiAl exhibits wear rates similar to 440C, with m
aterial removal proceeding by the formation of sub-surface voids and c
racks and the generation of plate-like wear debris typical of a delami
nation mechanism. The higher nickel containing materials such as Ni-40
% Al, undergo severe deformation with the formation of an ultra-fine g
rained sub-surface region. The hardness of this region exceeds 750 Hv.
Metal transfer from the 440C counterface is followed by oxidation of
the transferred film to form a FeO rich layer resulting in mild wear a
nd an order of magnitude reduction in wear rate compared with NiAl and
440C. (C) 1998 Elsevier Science S.A. All rights reserved.